-7,
Rhenium Complexes with the Umbrella Ligand
Tris(O-Mercaptophenyl)Phosphine
by
Sean Keenan Daughtry
B.S., Morehouse College (1993)
SUBMITTED TO THE DEPARTMENT OF CHEMISTRY
IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE
DEGREE OF
MASTER OF SCIENCE
at the
MASSACHUSETTS INSTITUTE OF TECHNOLOGY
February 1998
@Massachusetts Institute of Technology, 1998
Signature of Author_
,
peartment of Chemistry
September 19, 1997
Certified by
Alan Davison
Thesis Supervisor
Accepted by --------
..
.
.-
/
-
,i,---
-
-
-
-
-
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Dietmar Seyferth
Chairman, Departmental Committee on Graduate Students
MAR 03199
To Mom, Dad, Maya and
the entirety of my support system
Lord it's so hard, living this life
a constant struggle each and every day.
Some wonder why I'd rather die
than to continue living this way.
Many are blind and cannot find
the truth 'cause no one seems to really know.
But I won't except
that this is how it's goin' be
devil has got to let me and my people go.
'Cause I want to be free
completely free, lord won't you please come and save me.
'Cause I want to be free . . .
Goodie Mob
Rhenium Complexes with the Tripodal Ligand
Tris(O-Mercaptophenyl)Phosphine
by
Sean K. Daughtry
Submitted to the Department of Chemistry
on September 19, 1997 in partial fulfillment of the
requirements of the Degree of Master of Science
Abstract
CHAPTER 1. The synthesis and characterization of several trigonal
bipyramidal rhenium(III) tris(o-mercaptophenyl)phosphine complexes is
described. A host of rhenium(III) through rhenium(V) compounds
containing three halogens and at least one phosphine react with the
lithiated tris(o-mercaptophenyl)phosphine P(SLi)3 ligand to form trigonal
bipyramidal rhenium (III) complexes. Also an in situ reaction of P(SLi) 3
with ReBr3tht3 (tht=tetrahydrothiophene) and a sigma donor yields
trigonal bipyramidal PS3ReL complexes where L = PR3 or another sigma
donor. The X-ray crystallographic structure of P(o-C6H4S)3RePMe2Ph
shows a trigonal bipyramidal geometry. Crystal data for C26H23P2ReS3:
triclinic, P1 (#2), a = 10.29(1) A. b = 13.01(3) A, c = 10.14(1) A, B
=103.00(1), V = 1258(4) A3 to give Z = 2 and R = 0.034.
0
0
0
CHAPTER 2. The synthesis and characterization of several pseudooctahedral rhenium(III) tris(o-mercaptophenyl)phosphine complexes is
described. These six coordinate complexes were prepared either in situ
with ReBr3tht3 and a phosphine chelate or isocyanide or by passing CO
through a solution of a five coordinate PS3RePR3 in CH 2 Cl2. The six
coordinate complexes showed no evidence of contact shifts. The X-ray
crystallographic structure of P(o-C 6 H 4 S) 3 Re[(Me2P)2C2H4] shows a pseudo
-octahedral geometry. Crystal data for C2 4 H 2 8 P 3 ReS 3 : orthorhombic,
Pca21, a = 15.991(2) A, b = 18.213(4) A, c = 17.454(3) A, B = 900, V =
5083.5(14) A3 to give Z = 8 and R1 = 0.0352 and R2 = 0.0683.
Thesis Supervisor:
Title:
Dr. Alan Davison
Professor of Chemistry
Table of
Contents
Dedication......................................................................................................
Q uote...............................................................................................................
Abstract........................................................................................................
Introduction..................................................................................................
Chapter
1.
Trigonal Bipyramidal Tris(o-mercaptophenyl)phosphine
Rhenium (III) Compounds.
Introduction..........................
12
Experimental....................................................................
13
Results and Discussion...............................
............ 26
Notes and References ............................................................
Chapter
2
3
4
7
2.
39
Six Coordinate Tris(o-mercaptophenyl)phosphine
Rhenium (III) Compounds.
Introduction..........................
70
Experimental..........................
71
Results and Discussion ........................................................ 78
Notes and References...............................
............. 86
Acknowledgments..........................
111
Biographical Note....................................
112
List of Figures
1.1
Rhenium (III) complexes containing 2-(diphenylphosphine)-ethane............ 13
1-thiolate and monothiolate ligands.................................
1.2
Tris(o-mercaptophenyl)phosphine ligand preparation ...................
40
1.3
ORTEP diagram of PS 3RePMe2Ph.......................
42
1.4
Preparation of PS 3RePPh3, PS3RePMe2Ph, and PS 3 RePEt2Ph...........
54
1.5
Preparation of P1 and reactions with phosphines and
ph o sphites..............................................................................................................
56
1.6
UV-Vis spectrum of PS 3RePMe2Ph with additional PMe2Ph...........
58
1.7
Preparation of PS3Re arsines, stibines, and isocyanides using
P1................................................
60
1.8
Reaction and preparation of PS 3 Re(CO).............................
..........
62
1.9
IH NMR hydrogen labeling of five coordinate structures...............
64
1.10 1H NMR hydrogen labeling of five coordinate structures that
are phosphorus decoupled.....................................................................
66
1.11 IR Spectra of PS3Re(CO), PS3Re(CNdmp), & PS3Re(CNt-Bu).........
67
..................
70
2.1
PS3Tc(CNipr) and PS3Tc(CNipr)2...........................
2 .2
T c[P(C 6H4S)Ph2]3 ..................................................................................................
80
2 .3
R eB r3(CNp-tolyl)4................................................................................................
84
2.4
Reaction of PS3Rephosphines with CO....................................
2.5
ORTEP diagram of PS 3ReDMPE...........................................
89
2.6
Reactions of P1 with chelating phosphines...........................
101
2.7
Reaction of P1 with t-butylisocyanide ...................................................
103
2.8
1H
2.9
1H NMR hydrogen labeling for six coordinate structures that
are phosphorus decoupled...............................
.......
NMR hydrogen labeling of six coordinate structures..................
87
107
109
List of Tables
1.1
1H NMR, 31p NMR, and mass spectral data for trigonal bipyramidal
PS3Re phosphines........................................................23
1.2
1H NMR, 31p NMR, mass spectral, and IR data for trigonal
bipyramidal non phosphine PS3Re complexes...............................
32
............................. 38
1 .3
Phosphine cone angles......................................................
1.4
X-ray data for the structure determination of PS 3 RePMe2Ph .........
44
1.5
Bond lengths and angles for PS 3RePMe2Ph......................
..........
47
1.6
Atomic coordinates [x 104 ] and equivalent isotropic
displacement parameters [A2 x 103] for PS 3 RePMe2Ph................
. 51
2.1
1H NMR, 31p NMR, mass spectra and IR data for six coordinate
PS3R e complexes.......................................... .................................................. 74
2.2
X-ray data for the structure determination of PS3ReDMPE...........
2.3
Bond lengths and angles for PS 3ReDMPE...........................
2.4
Atomic coordinates [x 104] and equivalent isotropic
displacement parameters [A2 x 103] for PS 3 ReDMPE......................
98
Magnetic Susceptibility data of PS 3ReDMPE..........................
105
2.5
..........
91
94
Introduction
The coordination chemistry of technetium has been extensively
developed over the last fifteen years due largely to the importance of the
isotope
9 9 mTc
in diagnostic nuclear medicine.
Many technetium
compounds that are used as radiopharmaceuticals have tetradentate
ligands. 1
Most tetradentate ligands which have been investigated with
technetium are planar. 1,2
These ligands have an equatorial arrangement
around technetium therefore if an ancillary ligand coordinates the
resulting geometry will be "square pyramidal."
If two ancillary ligands
occupy the available sites, the ligands will be trans to each other.
A
tripodal tetradentate, "umbrella", ligand would impose either a trigonal
bipyramidal coordination for one ancillary ligand or a distorted octahedral
coordination where the two ancillary ligands are cis to each other.
This
new coordination may have unusual properties on the resulting complexes
which might have future value in developing radiopharmaceuticals.
Sulfur and phosphorus are excellent donor atoms for technetium
which is evident in the extensive coordination chemistry of thiols and
tertiary phosphines with the group seven metal. 3 ,4
Two novel technetium
compounds featuring a tetradentate thiolate-phosphine,
"umbrella," ligand
are P(o-C 6 H 4 S) 3Tc(CNC3H7) and P(o-C 6 H 4 S) 3 Tc(CNC3H7)2. 5 These complexes,
due to their sterically hindered ligands, discourage C-S bond cleavage and
bridge formation.
This "umbrella" ligand also imposes either a trigonal
bipyramidal or distorted octahedral coordination about the metal center. 5
Such bulky ligands stabilize complexes and inhibit facile redox processes. 6
Technetium's group seven congener rhenium has provided a useful
framework for understanding and expanding technetium's coordination
chemistry. 7
Their similarities due to their periodic relationship and
'lanthanide contraction' cause them to have nearly identical radii. 8
Yet,
because third row transition metals, in general, have increased
coordination in comparison to their second row congener; a rhenium
tetradentate thiolate complex should be more likely to prefer, in
comparison to technetium, higher coordination numbers.
This reasoning is
also encouraged by the observation that rhenium forms stronger covalent
bonds than technetium. 9
The newly synthesized P(o-C 6 H 4 S) 3 Re(PPhMe 2 ) is the first
structurally characterized rhenium compound to incorporate the
tetradentate thiolate ligand tris(o-mercaptophenyl)phosphine
referred
to
in this thesis as P(SH) 3 . This compound is similar to an earlier ruthenium
complex, RuBr2[As(o-As(Ph) 2C 6 H4) 3],
10
which unlike the pentacoordinate
rhenium complex is hexacoordinate with a tripodal arsenic ligand.
Analogous tripodal ligand rhenium compounds Re[N(C2H2S) 3 ](PPh 3 ) and
Re[N(C 2 H2S)3](CNt-bu) have been synthesized yet are not as rigid, do not
possess aryl groups, and incorporate a nitrogen donor atom. 11 The goal of
this research was to synthesize and characterize compounds of rhenium
with the phosphine-thiolate tetradentate "umbrella" ligand and investigate
their reactivities.
10
References
Jurisson, S.; Berning, D.; Wei, J.; Ma, D. Chem. rev 1993, 93, 1137-
(1)
1156.
Baldas, J. The Coordination Chemistry of Technetium; Academic Press
(2)
Inc.: New York, 1994; Vol. 41, pp 62-76.
Bandolini, G.; Mazzi, U.; Roncari, E.; Deutch, E. Coord. Chem. Rev. 1982,
(3)
44,
191-227.
(4)
Melnik, M.; Van Lier, J. Coord. Chem. Rev. 1987, 77, 275-324.
(5)
de Vries, N.; Cook, J.; Jones, A. G.; Davison, A. Inorg. Chem 1991, 30,
2662.
(6)
de Vries, N. H. C. PhD Thesis, Massachusetts Institute of Technology,
1988.
(7)
Davison, A. The Coordination Chemistry of Technetium; Cortina
International:
Verona, Italy, 1983, pp 3-14.
Schwochau, K. Some Fundamental Aspects of Technetium Chemistry;
(8)
Cortina International: Verona, Italy, 1986, pp 13-23.
(9)
Greenwood, N. N.; Earnshaw, A. Manganese, Technetium, and
Rhenium; Pergamon Press: New York, 1984, pp 1215-1241.
(10)
Mais, R. H. B.; Powell, H. M.; Venanzi, L. M. Chem. Ind. (London) 1963,
1204.
(11)
Spies, H.; Glaser, M.; Pietzcsh, H.; Hahn, F.; Kintzel, O.; LiUgger, T.
Angew. Chem. Int. Ed. Engl. 1994, 33, 1354.
Chapter One
Trigonal
Bipyramidal PS3ReL
Compounds
Introduction
Maina and coworkers have shown that stable five coordinate Tc(III)
complexes
and Re(III)
with the
2-(diphenylphosphine)-ethane- l-thiolate
and monothiolate ligands could be prepared. 1
along with the tris(o-mercaptophenyl)phosphine
These ligands
[figure 1.1].
ligand have
a
The metal in
combination of a phosphine and a thiolate "soft-donor" group.
these complexes has a +3 oxidation state and a d 4 configuration.
A
coordinated tripodal ligand, due to the "chelate effect", offers a stable
metal(III) core.
This can allow the study of the metal-ligand core's
coordination with donor ligands that could be possible biological anchors.
S-
Re
SR
S-Re*
R = Et, Ph, CH 2 PPh 2, CH 2P(O)Ph 2
Figure 1.1
Experimental
All manipulations have been carried out under a dry atmosphere of
either nitrogen or argon using Schlenk techniques.
Complexes were
treated as air sensitive until their stability was verified.
Toluene, hexanes,
THF, and ether were freshly distilled over Na/benzophenone.
3 1P
1H NMR and
NMR spectra were acquired on a Varian 300 XL or Varian 500 VXR.
IR
spectra were acquired on a Perkin-Elmer FT-IR 1600 series spectrometer.
Elemental analyses were performed by Atlantic Microlab Inc., Norcross,
GA.
High resolution Fast Atom Bombardment (FAB) mass spectra were
determined in a 3-nitrobenzylalcohol matrix on a Finningan MAT 8200
X-ray structures were determined by Dr. William
mass spectrometer.
Davis on a Rigaku AFC6R diffractometer and on a Siemens SMART/CCD
diffractometer.
Magnetic susceptibility measurements were performed on
a SQUID magnetometer.
Preparation of
Tris(o-mercaptophenyl)phosphine
P(SH)3.
The synthesis of P(SH)3 is sensitive and crucial and illustrated in
figure 1.2.
Care must be taken at all times during the synthesis because
the intermediates decompose with the slightest contact to air.
In a Schlenk flask 9.32 mL (0.091 moles) of dry thiophenol [99+%
Aldrich] was dissolved in 30 mL of dry cyclohexane (distilled over
Na/benzophenone and tetraglyme) and cooled to 0 oC.
In another flask 31
mL (0.20 moles) of tetramethylenediamine, TMEDA, and 80 mL (0.20
moles) of 2.5 M n-BuLi in hexane were dissolved in 150 mL of dry
cyclohexane at 0 oC.
By cannula, the n-BuLi solution was slowly added to
the thiophenol at 0 'C and stirred for one hour then allowed to stir for 22
hours at room temperature. 2
The excess solvents and reactants were
removed by decantation via cannula.
The dilithium salt was washed with
dry hexane 50 mL at 0 oC three times.
The dilithium salt was dissolved in
150 mL of dry THF at -78 'C.
A solution of 2.63 mL (0.030 moles) of PC13
was prepared in 50 mL of dry THF and cooled to -78 'C.
The PC13 solution
was transferred slowly via cannula to the dilithium salt over the course of
one hour.
The reaction was allowed to stir at room temperature overnight.
A 0.81 M solution of H2S04 was prepared and cooled to 0 'C.
The acid
solution was transferred via cannula to the reaction solution while both
solutions were at 0
temperature.
OC3
and they were allowed to stir for one hour at room
The pH was adjusted to one, indicated by universal indicator,
and the THF and some of the water was removed in vacuo. The P(SH) 3 was
extracted from water with ether, and the ether was dried with Na2S04.
The ether was removed in vacuo to obtain the crude P(SH) 3 . The P(SH) 3
was recrystallized in hot methanol to give a white powdery solid. 4
Yield:
2.87 grams (26%) mp. 151 'C.
1H
NMR (CDC13): 8 4.07 (s, 3 H, SH), 6.78 (m, 3 H, Ar), 7.08 (t, 3 H, Ar), 7.25
(t, 3 H, Ar), 7.38 (t, 3 H, Ar).
I.
3 1P
NMR (CDC13 ): 8 -25.6 (s).
Preparation of PS 3 RePhosphines
Preparation of PS 3 RePPh3 (1).
Compound (1) was prepared seven ways.
In the first method 0.2699
g (7.53 x 10- 4 moles) of dry P(SH) 3 were dissolved in 130 mL of dry THF
and deprotonated with 0.338 mL (2.26 x 10- 3 moles) of 1,8diazabicyclo[5.4.0]-undec-7-ene, dbu.
After cooling to 0 'C, 0.6283 g (7.53
x 10- 4 moles) of Re(O)C13 (PPh3)2 5 was added. There was a color change at
O0C that continued as the solution was allowed to warm to room
temperature.
This reaction was allowed to stir overnight, and the next day
it was a dark rose-purple.
product was a brown solid.
filtered.
The THF was removed in vacuo and the
This was redissolved in dry toluene and
After recrystallization by the slow evaporation of toluene, the
brown product had needle like crystals.
Yield 0.181 g (30%)
When using
P(SLi) 3 (described in method 3), the yield increases to (61.72%).
In the second method, 0.0763 g (0.0844 mmoles) of Re(NPh)C13 (PPh 3 )2 6 were added to a 25 ml solution of 0.030 g (0.0844 mmoles) of
P(SH) 3 and 0.037 mL (0.252 mmoles) of dbu in dry THF.
This reaction was
allowed to reflux overnight and turned a dark brown.
The crude product
was purified as above.
Anal. Calc. for C3 6H 2 7 S3 P2Re: C, 53.78; H, 3.39; S, 11.96. Found: C,
54.12; H, 3.61; S, 11.48.
In the third method, 0.050 g of dry P(SH)3 were charged to a 100 mL
Schlenk flask, placed under argon, and dissolved in dry THF.
The ligand
was deprotonated with 0.42 mL (3 equivalents) of 1.0 M LiN(TMS)2 in THF
(TMS = trimethylsilane).
After stirring for 30 minutes, the THF and
HN(TMS)2 were removed in vacuo and the ligand reactant (P(SLi)3) was
redissolved in dry THF. Next, 0.1198 g of ReC13 (PPh 3 )2CH3CN 7 was added
to the ligand reactant.
The mixture was refluxed under argon for 2 hours
and in air overnight, and the resulting solution was brown.
was dried in vacuo
The product
and then redissolved and filtered in toluene.
The
product was recrystallized from CH2C12/pentane.
In the fourth method, P(SLi)3 was prepared from 0.050 g of dry
P(SH) 3 as in method 3, and this was reacted with 0.1190 g (one equivalent)
of ReC14(PPh3)2 8 . The work up was analogous to method 3.
The fifth method used the same procedure as method 3 and 0.0976 g
(one equivalent) of ReC13bipyPPh3 7 (bipy = 2,2' bipyridine).
Yield (48%).
In method six the same procedure was used as in method 3 and
0.1068 g (one eq.) of ReC13 benzilPPh37 [benzil = C6 H 5 C(O)C(O)C6H5]. Yield
(70%).
In a seventh method 0.0769 g of PPh 3 (2.1 equivalents) were reacted
with P1 (described in preparation of compound (4) producing the brown
product.
Yield (69%).
Preparation of PS 3 RePMe2Ph (2).
Compound (2) was prepared two ways.
In method one, a dry
0.2532 g (7.07 x 10 - 4 moles) sample of P(SH)3 was placed under argon in a
200 mL Schlenk flask and dissolved in 130 mL of dry THF.
deprotonated with 2.12 mL of 1.0 M LiN(TMS)2 in THF.
The ligand was
The mixture was
The
stirred for 30 minutes, the THF and HN(TMS)2 were pumped off.
P(SLi) 3 was redissolved in dry THF.
ReC13 (PMe2Ph)3 9 was added.
Next 0.500 g (7.07 x 10- 4 moles) of
The reaction was allowed to warm to room
temperature and refluxed overnight to give a blood-red solution.
The THF
was removed in vacuo, and the product was redissolved in acetonitrile and
refluxed again in air to give a brown solution. This solution was cooled,
then filtered.
with water.
The impurities and excess phosphine-oxide were extracted
The product was dried in vacuo
and recrystallized in
Yield: 0.3813 g
CH 2 C12 /MeOH to obtain brown X-ray quality crystals.
(79%).
Compound (2) decomposes near 160'C.
Anal. Calc. for C 26 H 2 3 S3P2Re: C, 45.93; H, 3.41; S, 14.15. Found: C,
45.23; H, 3.40; S, 14.41.
X-ray structure is shown in [figure 1.3].
In the second method
0.08225 g of ReC13 bipyPMe2Ph was added to
one equivalent of P(SLi)3 in dry THF.
and the solution became brown.
The reaction was refluxed overnight,
The THF was removed in vacuo , and the
product was redissolved in toluene and filtered.
The brown product was
"crashed out" from toluene with pentane, collected on a frit and
recrystallized in CH2C12/MeOH to give brown crystals.
Yield (42%).
Preparation of PS 3 RePEt2Ph (3)
One equivalent of ReC13 (PEt 2 Ph) 2 CH3CN 0.0930 g was charged to a
solution of P(SLi) 3 in dry THF made from 0.050 g of P(SH)3 and 0.42 mL of
LiN(TMS)2.
The solution was refluxed overnight.
The resulting red-brown
solution was filtered and the THF was removed in vacuo. The solid product
was red-brown which can be recrystallized from CH2C12/heptane but no Xray quality crystals were obtained.
The physical characterization is found
in table 1.1.
Preparation of PS 3 ReP(n-Bu)3 (4)
The preparation of all subsequent phosphines involves the in situ
preparation of P1.
In a 50 mL Schlenk flask 0.050 g of P(SH) 3 were placed
under argon and dissolved in dry 10 mL of THF.
The ligand was
deprotonated with 0.42 mL of 1.0 M LiN(TMS)2 and stirred for 30 minutes.
The THF and HN(TMS)2 was removed under vacuum and the resulting
P(SLi)3 was redissolved in dry THF.
The P(SLi) 3 is transferred via
cannula to a 2-pronged 100 mL flask equipped with a reflux
condenser
containing a 10 mL solution of 0.0964 g of ReBr3tht310 in 10 mL of dry
The solution is brought to reflux and prior to reflux a burgundy-
THF.
wine color is reached.
At reflux 0.14 mL (4 equivalents) of P(n-Bu)3 is added.
The reaction
became red-brown and continued to reflux under argon for an hour.
reaction was cooled and a white solid was filtered off.
pumped down overnight.
refluxed in air.
The
The filtrate was
The product was redissolved in acetonitrile and
The solvent was removed in vacuo and the solid was
redissolved in Et 2 0, a brown solid slowly precipitated and was collected on
a frit and dried in vacuo.
Yield (80)%.
The physical characterization is
found in table 1.1.
Preparation of PS3RePEt3 (5)
P1 was prepared analogous to (4).
At reflux under argon 0.293 mL
(2.1 equivalents) of PEt 3 was added to P1 and the solution became redbrown. The reaction was refluxed for an hour under argon and became
brown.
The reaction was refluxed an additional two hours under air and
remained brown.
This was cooled and a white solid was filtered off.
The
solvent was pumped off and the solid product was dried overnight in
vacuo.
The product was redissolved in minimal CH 2 Cl 2 and a brown solid
was obtained upon addition of pentane and this solid was filtered off.
The
pentane filtrate was dried in vacuo, and the pentane soluble product was
a clean brown solid.
The physical characterization is found in table 1.1.
Preparation of PS 3 RePPh2py (6)
P1 was prepared analogous to (4).
At reflux under argon 0.0454 g of
PPh2py (py = pyridyl), (1.2 equivalents) was added to P1 and the solution
The reaction was refluxed for two hours in argon and two
became brown.
hours in air.
The color remained brown.
and dried overnight in vacuo.
The solution was cooled, filtered
The green-brown solid was dissolved in
CH 2 C12 (brown in solution) and crashed out with pentane.
product was collected on a frit and dried in vacuo.
The brown
The product was
slightly soluble in the pentane filtrate and clean brown crystals slowly
precipitated out.
II.
The physical characterization is found in table 1.1.
Preparation PS 3 RePhosphites
Preparation of PS 3 ReP(OMe)3 (7)
P1 was prepared analogous to (4).
At reflux under argon 0.034 mL
(2.1 equivalents) of P(OMe)3 was added to P1, and the solution became
brown.
The reaction was refluxed for two hours and the solution remained
brown.
The solution was cooled, filtered, and the solvent was removed
overnight in vacuo.
The red-brown solid was redissolved in CH 2 Cl 2 and
"crashed out" with pentane.
The product was slightly soluble in the
pentane filtrate, and a clean red-brown product was recovered.
physical characterization is found in table 1.1.
The
Preparation of PS 3 ReP(OEt)3 (8)
P1 was prepared analogously to (4).
This complex was prepared
analogously to (7) using 0.048 mL (2 equivalents) of P(OEt)3.
product was green.
The pure
The physical characterization is found in table 1.1.
PS3Re
III. Preparation of
Arsines
and Stibines
Preparation of PS 3 ReAsPh3 (9)
P1 was prepared in the dry box.
At reflux in THF under nitrogen,
0.2138 g (5 equivalents) of AsPh3 were added to the reaction and refluxed
for an hour.
The solution became red-brown.
a white solid was filtered off.
The reaction was cooled and
The solvent was removed overnight in vacuo
and the solid was redissolved in minimal CH 2 C12 and precipitated with
pentane.
The product was collected on a frit and excess AsPh3 was washed
away with pentane.
The dark brown product was dried under vacuum.
The physical characterization is found in table 1.2.
Preparation of PS3ReSbPh3 (10)
Compound
(10) was prepared two ways.
In the first method, similar
to the preparation of PS3RePPh3, P(SLi) 3 prepared from 0.0750 g of P(SH)3
and 0.63 mL of LiN(TMS)2 was refluxed with 0.2125 g (1 equivalent) of
Re(O)C13(SbPh 3 )25 in degassed bis(2-methoxyethyl)ether (diglyme) dried
over molecular sieves.
At reflux the solution became brown.
The mixture
was cooled and filtered and the diglyme was removed under vacuum.
The
product was redissolved in minimal CH 2 Cl2 and "crashed out" with excess
pentane.
The brown product was collected on a frit, washed with pentane,
and dried under vacuum.
Recovered 0.1021 g
Yield 54.5%
The second method followed the same preparation as (9)
except
0.2000 g (4 equivalents) of SbPh 3 was used.
The physical characterization
is found in table 1.2.
IV.
Preparation of PS3Relsocyanides
Preparation of PS3ReCN(t-Bu) (11)
To a solution of P1 0.017 mL (1.1 equivalent) of t-butylisocyanide
added via a syringe under argon.
is
The solution instantly becomes purple.
After refluxing for 1-2 hours the mixture is cooled, filtered, and all solvent
was removed and the solid was dried overnight in vacuo. The product is
dissolved in minimal CH 2 C12 and a purple solid is precipitated with
pentane.
The purple solid is collected on a frit, washed with pentane and
dried under vacuum.
chapter 2.
This purple solid will be discussed in detail in
The pentane filtrate is purple and also pumped dry.
The solid
product is redissolved in CH 2 C12 and allowed to slowly evaporate in air.
The resulting solid is washed with CH 2 C1 2 until no purple color persists and
the filtrate is pale brown.
A very small amount of a brown solid is
collected and dried in vacuo.
The physical characterization is found in
table 1.2.
Preparation of PS 3 ReCN(2,6-dimethylphenyl)
(12)
To a solution of P1, 0.0220 g (1.2 equivalents) of 2,6-dimethylphenylisocyanide in dry THF is transferred via
cannula.
The reaction
mixture became a bright red and then brown after two minutes.
brown color persisted throughout reflux.
The
The solution was refluxed under
argon for 90 minutes and another hour in air.
The mixture was cooled,
filtered, and all solvent was removed in vacuo overnight.
The product
was dissolved in CH2Cl2, and a white solid was filtered off. A solid dark
brown solid was precipitated with pentane collected on a frit, and washed
with pentane.
This solid was redissolved in CH 2 Cl2 and eluted through a
column of alumina in CH2Cl2.
The brown fraction which eluted first was
collected, filtered, and reduced in volume.
with pentane.
A brown solid was precipitated
Yield (20.5%)
Recovered 0.0193 g.
The physical
characterization is found in table 1.2.
V.
Preparation of PS3Recarbonyls
Preparation of PS3ReCO (13)
This complex can be prepared two ways.
In the first method, carbon
monoxide was directly bubbled into a solution of PS3ReP(n-Bu)3 or
PS 3 RePEt3 in CH2C12.
The solution immediately became purple, and the
bubbling was continued for another 15 minutes.
The solution is left under
CO pressure (ca 1 atm) for a duration longer than 10 days and the purple
color slowly gives way to brown.
was removed in vacuo.
vacuo
This solution was filtered and the solvent
The solid was washed with pentane and dried in
to remove volatile phosphines.
The yellow-brown product is a thick
oil at room temperature.
In the second method, CO is directly bubbled in to the P1 mixture at
room temperature for approximately 20 minutes.
The mixture is not
The solvent is
exposed to air and is kept under CO pressure for two weeks.
then removed in vacuo
and the brown solid is dissolved in CH 2 C12, filtered,
and precipitated with pentane.
The solid is collected on a frit and dried.
The pentane was removed in vacuo
from the yellow-brown filtrate to give
the same product that showed less impurity peaks in the
spectrum.
1H
NMR
The physical characterization is found in table 1.2.
Table
1H
1.1
NMR, 31p NMR, and Mass Spectrum Data For
Trigonal
Bipyramidal
PS3Re
Phosphines
Triganol Bipyramidal PS3Re Phosphines
Formula
PS 3 RePEt3
PS 3 ReP(nBu)3
PS 3 RePMe2Pht
PS 3 RePPh 3
1H
NMR in CD 2 C12 300 MHza, 500 MHzb
8 (ppm)
8.6b
7.5
7.3
7.2
2.2
1.2
8.5b
7.5
7.3
7.2
1.7
1,4
0.9
8.5 a
7.9
7.5
7.3
7.2
2.3
8.5 a
7.6
7.4
7.3
7.2
Mult.
t
d
t
t
m
m
t
d
t
t
m
m
m
t
m
m
t
t
d
t
m
m
t
t
Int & Assignment
3H PS 3 -1
3H PS 3 -4
3H PS 3-2
3H PS 3- 3
6H PEt 3
9H PEt 3
3H PS 3 -1
3H PS 3 -4
3H PS 3 - 2
3H PS 3 -3
6H P(n-Bu)3
12H P(n-Bu)3
9H P(n-Bu)3
3H PS 3 - 1
4H PS 3 -4 & phenyl
4H phenyl
3H PS 3 -2
3H PS 3-3
6H methyl
3H PS 3 -1
6H PS 3 -4 & phenyl
12H phenyl
3H PS 3 -2
3H PS 3-3
31p NMR 300 MHZ in CD 2 C12
PS3 8 ppm
d 142.6
PR3 8 ppm J p-p Hz
d
142.5
d
d
Mass Spec
(high res.)
239.8
661.038 (H+
amu
calcd.
661.038
d 9.9
241.4
744.132 (H+
amu
calcd.
744.132
140.4
d
-3.4
253.7
139.0
d
35.5
250.4
d
17.3
805.038 (H+
amu
calcd.
805.038
8 (ppm)
8.6 a
PS 3 RePEt2Ph
7.8
7.6
7.5
7.3
7.2
1.2
1.1
PS3RePPh2pyr 8.8b
8.59
7.9
7.7
7.5
7.4
7.36
7.31
7.2
PS3ReP(OMe)3 8.5 a
7.5
7.3
7.2
3.8
PS 3ReP(OEt)3 8.59a
7.5
7.3
7.2
4.1
1.4
Mult.
Int & Assignment
t
3H PS 3 -1
4H PS 3 -4 & phenyl
2H phenyl
2H phenyl
3H PS 3 -2
3H PS 3 -3
4H methylene
6H methyl
1H pyr
3H PS3-1
1H pyr
7H PS 3 -4 & pyr
4H phenyl
6H phenyl
3H PS 3-2
1H pyr
3H PS 3-3
3H PS3-1
3H PS3-4
3H PS3-2
3H PS3-3
9H (O-CH3)
3H PS 3 -1
3H PS 3 -4
3H PS 3 -2
3H PS 3 -3
6H (O-CH2-CH3)
9H (O-CH2-CH3)
m
m
m
t
t
m
m
d
t
t
m
d
m
t
t
t
t
d
t
t
d
t
d
t
t
q
t
Mass Spec
708.038 (H+
amu
calcd.
708.038
PS3 8 ppm
d 142.2
PR3 8 ppm
d 23.0
J p-p Hz
d
139.4
d 38.2
244.4
806.034 (H+
amu
calcd.
806.033
d
144.5
d
159.6
368.3
666.973 (H+
amu
calcd.
666.973
d
146.1
d
156.5
365.47
708.023 (H+
amu
calcd.
708.023
244.0
Results
and
Discussion
It has been demonstrated that the ligand tris(o-mercaptophenyl)phosphine, PS 3 , can be coordinated to rhenium to create trigonal
bipyramidal structures [figures 1.4 & 1.5].
PS 3 RePMe2Ph was the first of
these complexes where an X-ray structure was determined. [figure 4].
The
P-Re-P bond angle is 178.54(7)0 which is close to the expected bond angle
of 1800 for trigonal bipyramidal complexes.
In addition, the equatorial
The bond length of the
bond angles between the sulfur atoms are 120'.
(PS 3 ) P-Re is 0.148 A shorter than that of the (PMe 2 Ph) P-Re bond and the
Re atom is 0.0064 (3) A below the plane of the sulfur atoms.
The color of
this and subsequent trigonal bipyramidal PS 3 RePR3 compounds range from
brown to red-brown.
Several of these compounds can be grown as X-ray
quality crystals which are assumed to be similar in structure.
When the
reaction of P(SLi)3 with ReC13 (PMe2Ph)3 is prepared under an inert
atmosphere, a purple product can be isolated.
the rhenium precursor is ReC13bipyPMe2Ph.
This is not the case when
The
1H
NMR of this purple
product has broad aryl resonances at room temperature that do not show
definite splitting above -50 'C.
This broadening is due to excess phosphine
exchanging in the equatorial position in solution causing the coordination
about the metal atom to change from five to six continuously.
After
refluxing the purple product in air and removing the phosphine-oxide the
five coordinate compound is obtained.
This is determined from
1H
NMR
spectra where all resonances are sharp and 31p NMR spectra where there
are only two phosphorus resonances which are two doublets coupled
through the metal center.
[table 1].
The X-ray crystal structure and
elemental analysis confirmed that only one phosphine was coordinated to
the metal.
All products were characterized by 1H NMR and
3 1p
NMR
spectroscopy, high resolution mass spectra, and/or x-ray crystal structure
and elemental analysis.
[table 1.1].
When excess ligand is added to the
brown PS 3 RePMe2Ph and monitored by UV-Vis spectroscopy a new peak
grows in at 250 nm where there was not one originally.
becomes pink-purple.
[figure 1.6].
The solution also
There is no isosbestic point because
free PMe2Ph absorbs where the five and six coordinate compounds also
absorb.
The reaction of PS 3 with the Re(V) oxo complex, Re(O)C13 (PPh3)2,
takes place below room temperature whether it is deprotonated with dbu
or LiN(TMS)2 and with no additional reducing agent other than the already
coordinated triphenylphosphine.
In contrast, the reaction of PS 3 under
similar conditions with the isoelectronic imido complex, Re(NPh)C13(PPh3)2,
needs more robust conditions.
additional reducing agent.
The Re(IV) reaction also proceeds without
When the rhenium(III) ligand-metal core has a
choice of axial ligand between acetonitrile and triphenylphosphine,
such as
the reaction of PS(Li)3 with ReC13 (PPh3)2CH3CN, the ligand-metal core
coordinates the triphenylphosphine.
Whether this is a function of the
acetonitrile being trans to a phosphine or that the triphenylphosphine,
while more sterically encumbered, is a better pi acceptor has yet to be
determined.
When the rhenium(III) center has a choice of a chelating
nitrogen or oxygen donor ligand such as ReC13bipyPPh3 again it prefers the
phoshphine.
In fact, reaction method 6 which used ReC13 benzilPPh3 as the
metal precursor gave the highest yield of 70%.
The
1H
NMR is readily
interpreted with 27 aryl protons and the 31p NMR shows the phosphines
are coupled to each other through the metal center.
The positive Fast
Atom Bombardment (FAB) mass spectrum of this compound shows the two
expected mass peaks at 805 and 803 amu attributed to a species
The high resolution mass
containing the two natural isotopes of rhenium.
spectrum has a value of 805.0386 amu for both the observed and
calculated masses.
There is also a mass peak at 542 amu which
[table 1.1].
is the calculated weight of the parent PS3Re core. The two isotope peaks,
the correct mass value, and the ligand-metal parent peak are consistent for
all subsequent trigonal bipyramidal
compounds.
The preparation of PS 3 RePEt 2 Ph was noteworthy in the fact that the
reaction solution was red-brown and never purple.
This is interesting
because the rhenium precursor, ReC13 (PEt 2 Ph)2CH3CN, provides two
A possible
equivalents phosphine yet the solution remained brown.
reason the second PEt 2 Ph shows no evidence of coordination is its cone
angle is larger than PMe2Ph.
[table 1.6].
The
1H
that of the trigonal bipyramidal PS 3 RePMe2Ph.
NMR is almost identical to
The
3 1P
NMR spectra also
consists of two doublets coupled through the metal center.
The reaction solution P1 [figure 1.5] has yet to be fully characterized.
When P(SLi)3 is cannula transferred to a solution of ReBr3tht3, a color
change happens almost immediately from gold to brown.
solution becomes a wine color.
exist in situ.
When heated the
It is thought that PS3Retht2 and PS 3 Retht
Attempts to isolate either compound have been unsuccessful
and since THF is a weakly coordinating ligand, the possibility of a
PS 3 Re(THF)x or mixed THF, tht complex also exists.
stable in moist air.
The
1H
The product is not
NMR spectra shows broadening of aryl and
alkyl resonances which could be due to ligand exchange or paramagnetic
broadening.
When the reaction of P(SLi)3 and ReBr3tht3 is run in
CH 2 C12/toluene the solution does not become wine colored but brown.
Unfortunately, no product could be isolated despite the encouraging color.
Yet, the very instability of this ligand system makes it a prime candidate
for ligand exchange.
The first ligand reacted with the new P1 method was PPh 3 .
Since
this is an established PS3Re compound it will allow for an understanding of
The PPh 3 (5 equivalents) was added via
the reaction rate and yields.
cannula transfer in a solution of dry THF to the wine colored P1. The
solution became red-brown to brown after about five minutes and
remained so throughout the reaction.
The yield of the reaction was 69%
after working up the product.
This preparation method was followed for other phosphines such as
P(n-Bu)3 and PEt 3 where no rhenium precursor was available.
The same
result of the reaction mixture changing from wine colored to brown upon
addition of ligand was observed.
pyridyl).
One such phosphine is PPh2py (py =
The pyridyl nitrogen has been reported to coordinate to
transition metals, 1 1 and that was a possibility with the PS3Re core.
When
the pyridyl phosphine was added to the P1 mixture the solution became
brown, signaling that a five coordinate compound had been prepared.
After working up the product, the
1H
NMR spectra showed the familiar
resonance pattern of a trigonal bipyramidal product, and the
3 1P
NMR
spectra had two doublets with approximately the same coupling constants
as previous trigonal bipyramidal compounds.
This same preparation method was also followed to prepare
PS 3 Rephosphite compounds.
Two equivalents of trimethylphosphite were
added to the wine colored P1 reaction mixture during reflux in THF.
The
reaction mixture turned brown after almost 10 minutes and remained so
throughout the reaction.
the signature
1H
The clean end product was red-brown and had
NMR spectra in the aryl region of trigonal bipyramidal
PS3Re compounds.
phosphorus atom.
The methoxy protons were doublets split by the
There was no evidence of a six coordinate compound,
and the 31P NMR spectra had two doublets with a much larger coupling
constant than the phosphine compounds.
Even though P(OMe)3 has a
smaller cone angle than PMe 2 Ph [table 1.3], the electronic differences
between phosphines and phosphites probably prohibit the formation of a
six coordinate complex.
When the P1 mixture is reacted with P(OEt) 3 using the same method,
a brown color also is reached after roughly 10 minutes and remains
throughout reflux.
Interestingly enough, the product, after precipitation
from CH 2 C12 with pentane and collection on a frit, is green. This is also
green in solution yet has almost the same 1H NMR spectra of the
PS 3 ReP(OMe)3 compound.
The 3 1p NMR spectra also has two doublets with
approximately the same coupling constant.
One interesting feature is when
the solution of the compound is concentrated in vacuo
flashes of purple
can be seen but there is no evidence of a six coordinate compound or even
rapid ligand exchange.
The optical spectrum shows the two characteristic
peaks at 408 nm and 478 nm of trigonal bipyramidal PS3Re phosphines
even though there is a green colored solid and solution.
The reactions of the arsine and stibine yielded the expected results.
No purple color was observed during the reactions with P1 and the
products were brown and air stable.
The reaction of P(SLi) 3 with
Re(O)C13 (SbPh3)2, unlike that of Re(O)C13(PPh3)2, required not only a reflux
but a reflux in diglyme at 162 0 C.
The
1H
NMR spectra of both the arsine
and stibine compounds has a spectra almost identical to PS 3 RePPh3.
1.2]
The
3 1P
[table
NMR spectra has a single phosphorus resonance at 140.1 and
141.8 ppm for the arsine and stibine complexes respectively.
The reaction of the P1 mixture with t-butylisocyanide will be
discussed in greater detail in the next chapter.
What is noteworthy is that
the five coordinate product can be separated from the six coordinate
compound when washed with CH2Cl2 yet when this purple mixture is
eluted through an alumina column in CH 2 Cl2 no brown fraction can be
separated.
The washing technique though effective is not efficient because
much of the PS 3 ReCNt-Bu is lost because of its solubility in CH 2 Cl 2.
Continued on page 35
Table
1H
1.2
NMR, 31P NMR, Mass Spectrum, and IR data for
Trigonal
Bipyramidal
non-Phosphine
PS3Re
Complexes
Triganol
Formula
PS 3 ReAsPh3
1H
8 (ppm)
8.6
7.6
7.5
7.3
7.2
8.6
7.7
PS 3 ReCNt-Bu
PS3ReCNdmp
PS3Re
Non-phosphine
NMR in CD 2 Cl 2 300 MHz on Varian
7.4
PS 3 ReSbPh3
Bipyramidal
7.5
7.4
7.3
7.2
8.5
Mult
t
m
d
m
t
t
t
m
d
m
m
m
t
7.5
d
7.3
7.2
t
t
1.7
s
8.5
7.5
7.4
7.2
7.1
2.7
2.4
Int & Assignment
3H PS 3 -1
7H phenyl
3H PS 3 -4
7H phenyl
3H PS 3 -2
3H PS 3 -2
3H PS 3 -1
6.5H phenyl
3H PS 3 -4
8.5H phenyl
3H PS 3 -2
3H PS3-3
3H PS 3 -1
3H PS3-4
3H PS3-2
3H PS3-3
9H t-Bu
3H PS3-1
3H PS 3 -4
3H PS 3 -2
PS 3 and phenyl
PS3 and phenyl
methyl
methyl
compounds
Mass Spectra
(high
resolution)
IR cm- 1
848 amu
calcd. 848
(low res)
NA
141.8
895 (H+) amu
calcd. 895
(low res)
NA
137.7
625.012 amu
calcd. 625.013
2115.2 CN
137.9
674.020 (H+)
amu
calcd. 674.020
2058.2 CN
31p NMR in
CD 2 C12 , 300MHz
8 PS 3 (ppm)
140.1
Formula
1H
NMR in CD 2C1 2 300 MHz on Varian
31P NMR in
CD 2C1 2 , 300MHz
PS 3 ReCO
8 (ppm)
8.4
7.5
7.4
7.3
dmp = 2,6-dimethylphenyl
Mult
Int
3H
3H
3H
3H
& Assignment
PS3Re-1
PS3Re-4
PS3Re-2
PS3Re-3
Mass Spectra
(high
resolution)
IR cm-
5 PS 3 (ppm)
135.7
1951 CO
The
1H
NMR spectra of PS3ReCNt-Bu shows the four resonance aryl pattern
indicative of the coordinated PS 3 ligand and the 31P NMR spectra has a
[table 1.2]
single phosphorus resonance at 137.7 ppm.
The IR spectra has
a single stretch at 2115.2 cm - 1
The reaction of P1 with 2,6-dimethylphenylisocyanide
better way of preparing a five coordinate PS3Reisocyanide
(dmp) is a
compound.
Although the reaction at reflux is brown, chromatography on an alumina
column is required to obtain a pure product.
The lack of a purple reaction
color can indicate no six coordinate product is in competition with the five
coordinate compound yet the yield is only 20% which leaves questions as
to either the purity of the isocyanide or whether it is sterically
encumbered enough to prohibit bis coordination.
The 1H NMR spectra has
a more complex aryl region due to the phenyl protons on the isocyanide
but it does have the characteristic triplet at 8.5 ppm common to all PS 3 Re
trigonal bipyramidal compounds.
The
3 1P
NMR spectra has a single
phosphorus resonance at 137.9 ppm and the IR spectra exhibits a single CN
stretch at 2058.2 cm - 1 .
[table 1.2].
The IR stretches of PS 3 ReCNt-Bu and
-1
PS3ReCNdmp of 2115.2 cm - 1 and 2058.2 cm respectively, are similar to
the CN stretches of 2106 cm - 1 and 2053 cm - 1 for [Tc(CNMe)4bipy]
[Tc(CNdmp)4bpy]PF6 respectively
12 .
and
The major difference between the
isocyanides is the 'R' group which is either alkyl or aryl.
The reaction of PS3Rephosphines with CO will be discussed in greater
detail in the next chapter.
What is most interesting in this reaction is that
the purple color which appears immediately upon CO addition slowly gives
way to brown while still under CO pressure during a two week period.
purple color cannot be re-obtained by bubbling in more CO or adding
excess phosphine.
The resulting yellow-brown oil has a four resonance
The
aryl pattern but the two lower chemical shifts in PS3ReP(n-Bu)3 are shifted
downfield about 0.1 ppm.
Also, the doublet observed in the
[table 1.5].
31p NMR spectra of PS3ReP(n-Bu)3 at 142.5 ppm is now a singlet at 135.7
ppm and the other doublet is absent.
at 1951.4 cm- 1 .
The IR spectra shows a single stretch
This product is also obtained when CO is directly bubbled
into P1 but again the reaction is slow and takes two weeks.
The
phosphorus and proton NMR spectra of the PS 3 Re(CO) complex is the same
whether it is prepared from PS 3RePEt3. PS3ReP(n-Bu)3, or P1.
The trigonal bipyramidal compounds have a pseudo C3v symmetry.
The three aryl groups are observed as equivalent in 1H NMR spectra.
Therefore, only four aryl resonances are observed for the ligand.
One
would expect two doublets and two triplets, but for all observed
compounds there are three triplets and a doublet.
The aryl protons have
been labeled; H1 a triplet for the proton ortho to phosphorus, H2 a triplet
and H3 a triplet for the meta proton adjacent to H 1 and the proton para to
phosphorus respectively, and H4 a doublet for the proton ortho to sulfur.
[figure 1.7].
The H1 proton is designated so because its resonance is over a
whole ppm further downfield from the next closest proton resonance while
the other resonances are separated by only 0.23 to 0.11 ppm.
Also, the H 1
proton is projected towards the axis of the molecule while the other
protons are projected away from the molecule.
same
1H
NMR spectra is taken
3 1P
Furthermore, when the
decoupled, (specifically the PS3
phosphorus) the triplet becomes a doublet because it is no longer split by
the phosphorus.
[figure 1.8].
The H 4 proton is more accurately a doublet
of doublets and when the phosphorus is decoupled it becomes a sharp
doublet.
The H2 and H3 designations are more arbitrary but both show no
change when phosphorus is decoupled.
The 31p NMR spectrum is an equally powerful tool for
characterization.
resonance.
Of course all PS3Re compounds have a phosphorus
The chemical shift and multiplicity of the resonance along with
the associated coupling constants are key in understanding the
coordination of the compound.
chemical shift of -26 ppm.
The free P(SH) 3 31p NMR spectra has a
All known trigonal bipyramidal
PS3Rephosphine compounds have a coordinated PS3 31p resonance which is
a doublet between 142.6 ppm and 139.0 ppm.
The phosphorus is coupled
to the ancillary phosphine through the metal center; therefore, the 31p
resonance of the ancillary phosphine is observed as a doublet also.
This
doublet has a different chemical shift dependent upon which phosphine is
used yet the coupling constant remains between, 253.7 Hz and 239.8 Hz.
For the PS3Rephosphites the coordinated PS 3 doublet is between 146.1
ppm and 144.5 ppm.
The coupling constant for the PS3Rephosphites
is
between 368.3 Hz and 365.4 Hz, which is much larger than the coupling
constant of the phosphines.
Also, the chemical shifts of the phosphines
occur between 38.2 ppm and -3.4 ppm, while the chemical shifts of the
phosphite doublets occur around 158 ppm.
The non-phosphine trigonal bipyramidal PS3Re compounds also had
useful 31p NMR spectrum.
The isoelectronic PS 3 ReAsPh3 and PS 3ReSbPh3
had coordinated PS 3 singlets at 140.1 ppm and 141.8 ppm respectively.
This lies in the range for the PS3Rephosphines.
The two isocyanide
complexes, PS 3 ReCN(t-Bu) and PS3ReCNdmp (dmp= 2,6-dimethylphenyl),
have coordinated PS 3 31p NMR singlets at 137.7 ppm and 137.9 ppm
respectively.
ppm.
The PS3ReCO complex has a coordinated PS 3 singlet at 135.7
Thus, all known trigonal bipyramidal PS3Re compounds have a
coordinated PS3
3 1p
observed resonance between 135 ppm and 146 ppm.
Optical spectroscopy of the trigonal bipyramidal compounds revealed
two characteristics peaks around 400 nm and 500 nm.
This was true for
the phosphines, phosphites, and isocyanide complexes.
Not all reactions of P1 with sigma donors yielded stable trigonal
bipyramidal complexes.
Reactions of P1 with PC13 and PCy3 (Cy =
cyclohexyl) had uncharacterizable products.
Reactions of P1 with
acetonitrile, diethylamine, and pyridine also yielded uncharacterizable
products.
13
Ligand Cone Angles '
14
P(OMe)3 - - - - P(OEt)3 - - - - PMe2Ph - - - PC13 * ------PEt3 - - - - - --
107
109
122
125
132
P(n-Bu)3 - - -
132
136
PEt 2 Ph -----PPh3 ------- 145
PPh2py ----- -145
170
PCy 3 * -----* No PS 3 ReL complex was prepared.
Table
1.3
Conclusions
It has been demonstrated that the tris(o-mercaptophenyl)phosphine
ligand [P(SH) 3 ] can be coordinated as a trianionic ligand.
The P(SH) 3 ligand
promotes a trigonal bipyramidal coordination about the metal atom when
one ancillary ligand coordinates.
It is evident, however, that the PS 3 Re
core prefers ancillary ligands high on the spectrochemical series or those
that are excellent pi acceptors.
There is no evidence of the ligand-metal
core bonding with nitrogen donors such as pyridine or with extremely
bulky ligands such as PCy3. This is in due in part to rhenium as a third row
transition metal preferring "soft" ligands and, also, because the ancillary
ligand is trans to a phosphorus and therefore competing for electron backdonation.
Furthermore, because of the steric constraints on the tripodal
ligand, the ligand-metal core cannot coordinate with an extremely bulky
ligand.
References
(1)
Maina, T.; Pecorale, A.; Dolmella, A.; Bandoli, G.; Mazzi, U.; Nicolini, M. Rhenium(III)
Complexes Containing 2-(Diphenylphosphine)-Ethane-l-Thiolateand MonothiolateLigands.; SGE
Ditioriali: Padova, Italy, 1994; Vol. 4, pp 217-222.
(2)
Smith, K.; Lindsay, C. M.; Pritchard, G. J. J. Am. Chem. Soc. 1989, 111, 665.
(3)
Block, E.; Ofori-Okai, G.; Zubieta, J. J. Am. Chem. Soc. 1989, 111, 2327.
(4)
Millar, M., Preparation of PS 3H3 .
(5)
Johnson, N. P.; Lock, C. J. L.; Wilkinson, G. J. Chem Soc. 1964, 1054.
(6)
Chatt, J.; Dilworh, J. R.; Leigh, G. J. J. Chem. Soc. 1970, 2239.
(7)
Rouschias, G.; Wilkinson, G. J. Chem. Soc. (A) 1967, 993-1000.
(8)
Dziegielewski, J. O.; Machura, B.; Bartczak, T. J. Polyhedron 1996, 15, 2813-2817.
(9)
Parshall, G. W. Inorg. Syn. 1977, 17, 110.
(10)
Gardiner, I. M.; Bruck, M. A.; Wexler, P. A.; Wigley, D. E. Inorg. Chem. 1989, 28,
3688-3695.
(11)
Nicholson, T. L.; Hirsch-Kuchma, M.; Shellenbarger-Jones, A.; Davison, A.; Davis, W.
M.; Jones, A. G. Inorg. Chim. Acta. 1997, in press.
(12)
O'Connell, L. A. PhD Thesis, Massachusetts Institute of Technology, 1989.
(13)
Aldrich Inorganics, Aldrich: Milwaukee, WI, 1994; pp 322.
(14)
Greenwood, N., N.;; Earnshaw, A. Chemistry of the Elements; First ed.; Pergamon Press
Inc.: New York, 1984, pp 566-567.
Figure
1.2
Tris(o-Mercaptophenyl)Phosphine
Ligand
Preparation
Tris(orthomercaptophenyl)phosphine
Ligand preparation
SH
H2
+ 2.2 equiv
H3
C\
Li
H2
00 C
H2
cyclohexane
Si
-78 OC
/Cl
+ 1/3 equiv CI -P\
+ H 2 SO
P
4
SiU
Block, E.; Ofori-Okai, G.; Zubieta, J. J. A.
0---
H20
1 Chem.
Soc. 1989, 111, 2327
Figure
1.3
ORTEP diagram of PS 3 RePMe2Ph
C2
Ci5
C14
Ci
Ci7
C25
IC24
C26
Table
X-Ray
data for the
1.4
structure
PS3RePMe2Ph
determination
of
Empirical Formula
C26 H2 3 P2S3Re
Formula Weight
679.80
Crystal Color, Habit
purple,
Temperature
23 0 C
Diffractometer
Rigaku AFC6R
Wavelength
(A)
parallelepiped
MoKa (0.71069)
Crystal System
triclinic
Space Group
P1
a (A)
10.29
(1)
b (A)
13.01
(3)
(A)
10.14
(1)
a (o)
107.8
(1)
1 (o)
103.0
(1)
y
88.5
c
(0)
(#2)
(2)
Volume, (A3 )
1258
Z
2
D (calc.) (mg m- 3 )
1.795
Absorption coefficient (cm-1)
52.74
F000
664
Crystal to Detector Distance
40cm
Crystal Dimensions (mm)
0.400 x 0.300 x 0.300
Theta range (0)
2.02 to 25.05
Reflections collected
4712
Independent
reflections
(4)
4439 (Rint = 0.040)
Absorption
correction
trans. factors:
Refinement
method
Full-matrix
0.80 - 1.51
least-squares
Table 1.3 Continued
Goodness of Fit Indicator
1.27
FinMax difference peak (eA -3 )
Min. difference peak (eA -3 )
1.24
-1.14
Table
1.5
Bond lengths (A) and angles (0) for PS 3 RePMe2Ph
Intramolecular Distances Involving the Non-hydrogen Atoms
(A)
Atom
tom
Distance
tom
Atom
Distance
Re
(1)
2.240 (5)
(5)
C(6)
1.39(1)
Re
(2)
2.258 (5)
(7)
C(8)
1.39 (1)
Re
(3)
2.242 (4)
(7)
C (12)
1.40 (1)
Re
(1)
2.265 (4)
(8)
C (9)
1.38 (1)
Re
(2)
2.413 (4)
(9)
C (10)
1.39 (1)
S (1)
(6)
1.805 (8)
(10)
C (11)
1.38 (1)
S (2)
(18)
1.816 (8)
(11)
C (12)
1.41 (1)
S (3)
(12)
1.796 (8)
(13)
C (14)
1.39 (1)
P (1)
(1)
1.819 (9)
(13)
C (18)
1.38 (1)
P (1)
(7)
1.821
(8)
(14)
C (15)
1.38 (1)
P (1)
(13)
1.822 (8)
(15)
C (16)
1.38 (1)
P (2)
(19)
1.832 (9)
(16)
C (17)
1.38 (1)
P (2)
(25)
1.81 (1)
(17)
C (18)
1.41 (1)
P (2)
(26)
1.82 (1)
(19)
C (20)
1.39 (1)
C (1)
(2)
1.40 (1)
(19)
C (24)
1.36 (1)
C (1)
(6)
1.39 (1)
(20)
C (21)
1.39 (1)
C (2)
(3)
1.36 (1)
'(21)
C (22)
1.35 (2)
c (3)
(4)
1.39 (1)
'(22)
C (23)
1.40 (2)
C (4)
(5)
1.39 (1)
(23)
C (24)
1.42 (1)
Intramolecular Bond Angles Involving the Nonhydrogen Atoms
Atom
Atom
Atom
Angle
Atom
Atom
tom
Angle
S (1)
Re
S (2)
120.2 (1)
P (1)
c (1)
(6)
114.5 (6)
S (1)
Re
S (3)
118.6 (2)
C (2)
c (1)
(6)
119.0 (7)
S (1)
Re
s (3)
119.5 (1)
C (3)
C (4)
(5)
120.8 (8)
S (1)
Re
P (1)
86.0 (2)
c (1)
C (2)
(3)
120.6 (8)
S (1)
Re
P (2)
92.7 (2)
C (2)
c (3)
(4)
120.0 (8)
S (2)
Re
P (1)
85.4 (2)
C (4)
C (5)
(6)
119.0 (8)
S (2)
Re
P (2)
94.6 (2)
S(1)
C(6)
(1)
120.8 (6)
S (3)
Re
P(1)
85.6 (1)
S (1)
C (6)
(5)
118.6 (6)
S (3)
Re
P (2)
95.6 (1)
c (1)
C (6)
(5)
120.6 (7)
P (1)
Re
P (2)
178.54(7)
P (1)
C (7)
(8)
127.3 (6)
Re
S (1)
C (6)
108.5 (3)
P (1)
C (7)
(12)
113.6 (6)
Re
S (2)
C (18)
108.2 (3)
c (8)
C (7)
(12)
119.1
Re
S (3)
C (12)
108.8 (3)
C (7)
c (8)
(9)
121.0 (8)
Re
P (1)
c (1)
110.2 (3)
c (8)
c (9)
(10)
120.1 (8)
Re
P (1)
C (7)
110.8 (3)
c (9)
C (10)
(11)
120.2 (7)
Re
P (1)
C (13)
110.9 (3)
C (10)
C (11)
(12)
120.1 (8)
c (1)
P (1)
C (7)
108.7 (4)
s (3)
C (12)
(7)
121. (6)
c (1)
P (1)
C (13)
108.2 (4)
S (3)
C (12)
(11)
119.3 (6)
C (7)
P (1)
C (13)
107.9 (3)
C (7)
C (12)
(11)
119.6 (7)
Re
P (2)
C (19)
111.6 (3)
P (1)
C (13)
(14)
126.6 (6)
Re
P (2)
C (25)
116.8 (4)
P (1)
C (13)
(18)
114.2 (6)
Re
P (2)
C (26)
117.5 (3)
C (14)
C (13)
(18)
119.2 (7)
C (19)
P (2)
C (25)
104.0 (4)
C (13)
C (14)
(15)
121.6 (7)
C (25)
P (2)
C (26)
104.5 (5)
C (14)
C (15)
(16)
119.2 (8)
C (25)
P (2)
C (26)
100.7 (5)
C (15)
C (16)
C (17)
120.1
(7)
(8)
Atom
Atom
Atom
Angle
Atom
Atom
Atom
Angle
P (1)
C (1)
C (2)
126.5 (6)
C (16)
C (17)
C (18)
120.6 (8)
S (2)
C (18)
C (13)
121.2 (6)
C (19)
C (20)
C (21)
121 (1)
S(2)
C (18)
C (17)
119.5 (6)
C (20)
C (21)
C (22)
121 (1)
C (13)
C (18)
C (17)
119.3 (7)
C (21)
C (22)
C (23)
119 (1)
P (2)
C (19)
C (20)
120.4 (7)
C (22)
C (23)
C (24)
120 (1)
P (2)
C (19)
C (24)
120.1
(7)
C (19)
C (24)
C (23)
120 (1)
C (20)
C (19)
C (24)
119.0 (9)
Table 1.6 Atomic Coordinates (x 104)
Isotropic
Displacement
Parameters
PS 3 RePMe2Ph.
and Equivalent
(A2 x 103) for
Positional parameters
Atom
excluding the hydrogen atoms.
B(eq)
Z
Y
X
(3)
1.40 (1)
0.24902 (3)
0.23184
0.3852 (2)
0.4366 (2)
2.11 (7)
0.1303 (2)
0.1829 (2)
1.96 (7)
0.0029 (2)
0.2559 (2)
0.0567
(2)
2.08 (7)
P (1)
0.2879 (2)
0.3557 (2)
0.1501
(2)
1.44 (6)
P (2)
0.0622 (2)
0.1376 (2)
0.3250 (2)
2.05 (7)
C (1)
0.3408
(7)
0.4841 (6)
0.2878 (8)
1.7 (3)
C (2)
0.4098
(8)
0.5708 (6)
0.2755
(8)
2.1 (3)
C (3)
0.4416 (9)
0.6636 (7)
0.387 (1)
2.8 (3)
C (4)
0.4074 (9)
0.6722 (7)
0.514 (1)
3.1 (3)
C (5)
0.3386 (8)
0.5880 (7)
0.5297 (8)
2.2 (3)
C (6)
0.3066 (7)
0.4935 (6)
0.4162 (8)
1.8 (3)
C (7)
0.1820 (7)
0.3822 (6)
-0.0048
(7)
1.5 (2)
C (8)
0.2154 (8)
0.4440 (6)
-0.0832 (8)
2.2 (3)
C (9)
0.1225 (9)
0.4614 (7)
-0.1947
(9)
2.6 (3)
C (10)
-0.0056 (9)
0.4153
(8)
-0.2319 (9)
2.9 (3)
C (11)
-0.0413
(8)
0.3528
(7)
-0.1568
(8)
2.6 (3)
C (12)
0.0523
-0.0416 (8)
2.0 (3)
C (13)
0.4360 (7)
C (14)
0.5293
(7)
C (15)
Re
0.17705
S (1)
0.2148
S (2)
0.0.3368
S (3)
(3)
(2)
(2)
(8)
0.3359 (6)
(7)
1.5 (2)
0.3350 (7)
0.0480 (9)
2.1 (3)
0.6389 (8)
0.2790 (7)
0.013 (1)
2.7 (3)
C (16)
0.6572 (8)
0.1783 (7)
0.030 (1)
2.6 (3)
C (17)
0.5663
(8)
0.1340 (6)
0.0808 (8)
2.2 (3)
C (18)
0.4542 (7)
C (19)
0.1761
(8)
0.2915
(6)
0.0983
(6)
0.1153
(8)
1.7 (3)
0.0956 (7)
0.4641
(9)
2.2 (3)
0.1907
C (20)
0.204 (1)
0.1626 (8)
0.604 (1)
3.8 (4)
C (21)
0.303 (1)
0.138 (1)
0.707 (1)
5.2 (5)
C (22)
0.374 (1)
0.049 (1)
0.675 (1)
5.5 (6)
C (23)
0.347 (1)
-0.020 (1)
0.535 (2)
5.6 (6)
C (24)
0.246 (1)
0.0051 (9)
0.429 (1)
4.3 (4)
C (25)
-0.072 (1)
0.1978 (9)
0.407 (1)
3.7 (4)
C (26)
-0.021 (1)
0.0126 (8)
0.201 (1)
4.2 (4)
Figure 1.4 Preparation of PS 3 RePPh3, PS3RePMe2Ph,
and PS 3 RePEt2Ph
Complexes
Re(O)C13 (PPh 3 ) 2
Re(NPh)CI 3 (PPh 3 )2
ReCI3 (PPh 3)2CH 3CN
THF
+ P(S-) 3
refluxed
ReCI4 (PPh 3 ) 2
ReCl3bipyPPh 3
+
P(SLi) 3
THE
refluxed
Om
PPh 3
ReCl 3 benzilPPh 3
brown
ReCI 3 (PMe 2 Ph) 3
THE
+
P(SLi) 3
refluxed
ReCI 3 bipyPMe 2 Ph
I 's
PMe 2Ph
brown
ReCI 3 (PEt 2 Ph) 2 CH 3CN
+
P(SLi) 3
THE
refluxed
C?
' S
PEt2 Ph
red-brown
Figure
Preparation
1.5
of P1 and Reactions
and
Phosphites
With Phosphines
P1
P(SLi) 3
ReBr 3 (tht) 3
THF
refluxed
E=SorO
THF
PR 3
+
refluxed
R3 P
brown
R = Ph, n-Bu, & Et
P1
PPh 2py
+
THF
refluxed
brown
THF
+
P(OMe) 3
refluxed
S-Re.
(MeO) 3 P
red-brown to burgundy
+
P(OEt) 3
THF
refluxed
(EtO) 3 P
green
Figure
1.6
UV-Vis Spectra of PS3RePMe2Ph
with
additional
PMe2P h
222nm
PS 3RePMe 2Ph + PMe 2Ph in increments
2.0
250nm
1 .6
1
4
o1.2"
C
o0.8-
0.4
---~a~
0.2
200
220
240
280
300
260
Wave_1 e!ngth(nm)
Run 1 = 1 : 1of PS 3Re PMe 2 Ph to PMe 2 Ph
Run2= 1:2
Run3= 1:3
Run4= 1:4
Run5= 1:5
320
340
3C_
Figure
Preparation
of
1.7
PS3Re Arsines,
Isocyanides
using
Stibines and
P1
P1
P(SLi) 3 +
ReBr 3 (tht) 3
THF
refluxed
E
E
E=SorO
THF
P1
+
AsPh 3
refluxed
Ph 3 As
dark brown
THF
P1
+
SbPh 3
refluxed
brown
THF
P1
+
CN t-Bu
refluxed
NI
N
II
rN
royal purple
THF
P1
+
CN
refluxed
brown
brown
Figure
Reaction
1.8
and preparation
PS3Re(CO)
of
CO
S-1
CH2C12
R3 P
PR 3
brown
royal purple
R = Et & n-Bu
CO 1-2 weeks
CH 2 CI 2
PR 3
royal purple
yellow-brown
Compound
single IRstretch
PS 3 RePEt 3 CO
PS 3 ReP( n-Bu) 3C( O
PS3ReCO
1980.6 cm -1
1985.6 cm -1
1951.4 cm 1
Figures 1.9 & 1.10
Hydrogen labeling for
five
coordinate
1H
NMR of
structures
H2
H1
H3
H4
Hydrogen labeling for five-coordinate structures
in
-H 3
H4
II I
I I I I I I I I I
I I
8.6
I I I
I I'
I'
I
8 4
8.2
41 2
I I Il I
' 1I1I 1 I I I I
8.0
7.8
I
I
i
I I I i
7.6
I
NMR of PS 3ReP(n-Bu) 3 aryl region
II
I II
7 4
34 3
1H
I II
7.2
40 8
39 6
7.
H4
H1
H2
H3
Hydrogen labeling for five-coordinate structures
1H
2
.H 3
H4
8.6
8.4
8.2
8.0
7.8
7.6
36.04
7.4
7.2
5443
45.98
1H
NMR of PS3 ReP(n-Bu) 3 with 3 1 P decoupled
figure 1.10
50.11
Figure
IR Spectra of PS3 Re(CO),
1.11
PS 3 Re(CNdmp),
& PS3Re(CNt-Bu)
PS3Re(CO)
2200
2000
PS3 Re(CNdmp)
"-600
2500
2500
2000
2000
SPS 3Re(CNt-Bu)
2500I
2500
i
2000
Chapter
Six-Coordinate
Two
PS 3 ReL2
Compounds
Introduction
Although
trigonal bipyramidal
tris(o-mercaptophenyl)phosphine
compounds of rhenium have been prepared, there is evidence of higher
coordination number compounds.
are brown in color.
Most of the five-coordinate compounds
Their UV-Vis spectra show one medium peak around
400 nm and one broad peak around 500 nm with a lower intensity.
In the
presence of an excess of ligand certain reaction mixtures are wine/purple.
When a five coordinate complex is obtained from these solutions it is
brown in color but when treated with excess ligand it changes to purple.
The reported five coordinate PS3TcCN-i-pr is orange while the six
coordinate PS 3 Tc(CN-i-pr)2 is blue [figure 2.1] and can only be prepared
with a large excess of isocyanidel.
The observed brown to purple
relationship for the rhenium complexes is believed to be analogous to the
orange to blue phenomena with technetium.
To further investigate this
coordination six-coordinate PS3Re complexes were prepared.
Tc
S-Tc
III
I
H 3C
III
cH
H 3C
N
N
CH 3
I
CH
CH
\CH3
H3 C
orange
blue
Figure 2.1
CH 3
Experimental
The general experimental conditions are the same as those described
in chapter one.
The physical characterization of all complexes are found in
table 2.1.
I.
Preparation of PS 3 RePR3Carbonyls
Preparation of PS 3 RePPh3(CO)
(14)
A solution of PS 3 RePPh3 was prepared in CH 2 Cl2. To this solution CO
is bubbled in directly for 15 - 20 minutes.
The solution immediately goes
purple and must be kept under CO pressure to remain purple.
Compound
exists in situ.
Preparation of PS 3 RePEt3(CO)
(15)
A solution of PS 3 RePEt3 was prepared in CH 2 Cl 2 and CO was directly
bubbled through it for 15 minutes.
The solution immediately goes purple.
The complex exists in situ. The solvent was removed in vacuo and the
solid is purple but is unstable past 2-3 hours and reverts to brown (5)
unless kept under CO pressure.
Preparation of PS3ReP(n-Bu)(CO)
(16)
The preparation is analogous to (14) except PS3ReP(n-Bu)3 is used.
II.
Preparation of PS3Re(Chelating
Preparation of PS 3 ReDMPE
phosphines)
(17)
A solution of P(SLi)3, in dry THF, prepared from 0.075 g of P(SH)3
and 0.63 mL of 1.0 M LiN(TMS)2 is transferred via cannula to a twopronged round bottom flask containing a solution of 0.1446 g of ReBr3tht3
in dry THF.
This mixture is brought to reflux (P1).
(1.2 equivalents) of 1,2-bis(dimethylphosphinoethane)
During reflux 0.42 mL
(DMPE) is syringed
into the (P1) reaction.
The reaction was refluxed for three hours and then
and the solid was
cooled, filtered, and the solvent was removed in vacuo
dried overnight.
The product was dissolved in CH 2 Cl 2 , precipitated with
pentane, collected on a frit, and dried under vacuum.
The purple solid was
redissolved in CH2Cl2 and eluted through an alumina column.
The purple
fraction was collected, filtered and the solvent was removed in vacuo and
This product was again redissolved in
the solid was dried overnight.
CH 2 C12, layered with pentane and placed in the freezer.
Microcrystals were
obtained. The crystals were collected on a frit and dried under a vacuum.
The product was very pure.
X-ray quality crystals can be grown from slow
evaporation of CH 2 C12. Recovered 0.0261 grams.
Preparation of PS 3 ReDIPHOS
Yield (18)%
(18)
The reaction of this complex was analogous to (17) except 1.2
equivalents of 1,2-(bisdiphenylphosphinoethane)
dry THF solution instead of DMPE.
(DIPHOS) were used in a
The solvent was removed and the
product was dried in vacuo overnight and then dissolved in CH 2 C1 2 and a
solid was precipitated with pentane.
The pentane filtrate was purple.
The
filtrate was dried, and the purple solid was redissolved in CH 2 C12 and
eluted through an alumina column; the purple fraction was collected,
filtered, and the solvent was removed and the purple solid was dried in
vacuo
overnight.
Preparation of PS 3 ReTRIPHOS
(19)
The preparation of this complex was analogous to (18) except 1.1
equivalents
of bis(2-diphenylphosphinoethyl)phenylphosphine
were used in a dry THF solution in place of DIPHOS.
(TRIPHOS)
The product was
separated from the solvent under vacuum and the solid was dried
overnight in vacuo
and redissolved in CH2Cl2, and a white precipitate was
filtered off.
Pentane was added to solution, and a purple solid was
obtained.
This solid was collected on a frit, washed with pentane and dried
in vacuo.
The purple solid was redissolved in CH 2 C12 and eluted through an
alumina column.
The purple fraction was collected and filtered.
The
volume was reduced, and a solid was reprecipitated with the addition of
pentane.
This clean purple solid was collected on a frit and dried under
vacuum.
III. Preparation of
PS3Re(bis-isocyanides)
Preparation of PS 3 Re(CNt-Bu)2
(20)
The reaction mixture of P1 was brought to reflux and 2.5 equivalents
of tetrabutylisocyanide were added by syringe.
The reaction immediately
became purple and was allowed to reflux for an addition 2 hours.
reaction was cooled and a white solid was filtered off.
dried overnight in vacuo.
The
The product was
The product was redissolved in CH 2 C12 and a
The solution was filtered;
solid precipitated with the addition of pentane.
the solid was collected; the purple pentane filtrate was saved and all
solvent was removed under vacuum.
The collected solid is redissolved in
minimal CH2C12 and eluted through an alumina column in diethyl ether.
column was also run on the pentane filtrate.
A
The purple fraction was
collected from both columns and the solution was filtered and all the
solvent was removed.
The product from both columns was redissolved in
CH 2 C12 and a solid reprecipitated with pentane.
The purple pentane filtrate
was collected and dried, and the final clean product is purple.
Table
1H
2.1
NMR, 31P NMR, Mass Spectra and IR data
for six coordinate PS3Re
complexes
Six-Coordinate
Formula
1H
NMR in CD 2C12 300 MHZ Varian
8 ppm
PS 3 RePPh3(CO)
PS3ReP(nBu)3(CO)
PS3Re
8.5
8.0
7.6
7.5
7.4
7.3
7.2
7.0
8.5
8.0
7.7
7.5
7.3
7.2
7.1
7.0
1.6
1.4
0.9
Mult.
Int & Assignment
2H PS3-la
1H PS 3 -lb
3H PS3 and phenyl
4H PS3 phenyl
11H phenyl
2H PS3-2a
3H PS3-3a and PS 3 -2b
1H PS 3 -3b
2H PS3-la
1H PS 3 -1b
2H PS3-4a
1H PS3-4b
2H PS3-2a
2H PS3-3a
1H PS 3 -2b
1H PS 3 -3b
methylene
methylene
methyl
Compounds
31p NMR 300 MHz Varian in
CD2 Cl2
J pp Hz
8 PR 3
8 PS 3
ppm
ppm
d 111.1 d 3.65
194.6
d
114.9
d
-21.7
196.7
Mass Spec
IR cm- 1
High res
1996.9
CD
1985.6
(D3
8.5
8.0
7.7
7.5
7.3
7.25
7.20
7.0
2.2
1.2
PS 3 Re(CNt-Bu)2 8.4
7.9
7.6
7.5
7.3
7.2
7.1
6.9
1.7
0.8
8.5
PS 3 ReDMPE*
8.0
7.5
7.4
7.1
6.9
2.2
1.9
0.8
PS 3 RePEt 3 (CO)
3H PS3-la
1H PS 3 -l1b
1H PS 3 -4b
2H PS3-4a
2H PS3-2a
2H PS 3 -3a
1H PS 3 -2b
1H PS 3 -3b
6H methylene
9H methyl
3H PS 3 -la
1H PS 3 -1b
2H PS3-4a
1H PS 3 -4b
1H PS 3 -2b
2H PS3-2a
2H PS 3 -3a
1H PS 3 -3b
9H t-butyl
9H t-butyl
2H PS3-la
1H PS 3 -1b
2H PS3-4a
1H PS 3 -4b
5H PS3-2,3a and 2b
1H PS 3 -3b
4H methylene
6H methyl
6H methyl
d
116.0
109.3
d
117.3
d
-13.4
NA
NA
d
195.0
-11.3
-18.8
223.5
1980.6
C3
709.095
(H+) amu
calcd.
709.094
2140 .3
692.012
amu
calcd.
692.012
NA
CN
2099.2
CN
tPS3 ReDIPHOS*
b
8.6
PS 3
b
8.0
PS 3
m
7.8
Aryl
t
7.5
Aryl
t
7.4
Aryl
m
Aryl
7.3
Aryl
m
7.27
m
Aryl
7.2
t
Aryl
6.9
t
6.8
PS 3
t
6.7
PS 3
m
Alkyl
3.3
m
Alkyl
3.1
t
Aryl
PS 3 ReTRIPHOS* 8.6
t
8.5
PS 3
t
Aryl
8.3
t
Aryl
8.0
t
7.84
PS 3
t
Aryl
7.79
Aryl
7.5-7. 2 m
m
Aryl
7.1
t
Aryl
6.9
t
Aryl
6.8
m
Aryl
6.7
t
Aryl
6.6
m
Aryl
6.3
m
Alkyl
2.4
m
Alkyl
1.5
* = spectrum aquired on varian 500 MHz NMR
221.0
d
119.2
d 16.2
& 2.0
d
117.9
d 14.1 & 223.4
0.3 &
-12.7
941.082
(H+) amu
calcd.
941.082
NA
1077.1270
amu
1077.1269
calcd.
NA
Results
It has been demonstrated
and
Discussion
that the tris(o-mercaptophenyl)phosphine
ligand, when coordinated to rhenium, can support two ancillary ligands
coordinated to the metal center.
This "opening up," or the ability of the
ligand to allow higher coordinations than five, occurs when trigonal
bipyramidal
PS3RePhosphine and phosphite compounds are reacted with
carbon monoxide, or a chelating phosphine is reacted with the P1 mixture.
All
The ligand-metal core also allows for bis-coordination of isocyanides.
products were characterized by 1H NMR and 31p NMR spectroscopies, IR
spectroscopy (when applicable), high resolution mass spec., and/or X-ray
crystal
structure.
When a trigonal bipyramidal PS3Rephosphine or phosphite is
exposed to CO directly bubbled into the brown solution, it immediately
goes purple.
This is observed in reactions with the trimethylphosphite,
triethylphosphine,
compounds.
tri-n-butylphosphine,
and
triphenylphosphine
PS 3 Re
These ancillary ligands have in respective order, increasing
cone angles, yet the reaction with CO is not hindered.
[table 2.1].
Even
though a solution of PS3ReP(OMe)3 becomes purple when CO is passed
through, the complex becomes unstable, and no five or six coordinate
complex is observed.
This is not the case with the PS3Rephosphines
give rise to short-lived purple complex.
which
This vibrant purple complex in air
reverts back to brown and will revert to brown faster when nitrogen or
argon are passed through the solution.
When the purple compound is kept
under CO pressure for more than a week, it becomes yellow-brown which
is PS 3 ReCO (13).
The formation of the six coordinate PS 3 RePR3CO compounds can be
monitored by IR.
The KBr pellet or solution IR spectra show a single CO
stretch between 1997 cm-1 and 1980 cm-1 for the six coordinate
compounds.
[table 2.1].
PS 3 ReCO compound.
This stretch is 30 to 45 cm - 1 higher than for the
[figure 2.4].
Unfortunately, these complexes show
only the parent trigonal bipyramidal compound and the ligand-metal core
in the high energy of Fast Atom Bombardment (FAB) mass spectrum.
1H
NMR spectroscopy has proven to be a useful tool in characterizing
As stated earlier, the trigonal bipyramidal compounds
these compounds.
have a base three axis of symmetry that resulted in the three aryl rings
being magnetically equivalent.
If another ligand occupies the sixth
coordination site the symmetry is lowered and is no longer three-fold.
Therefore, only two aryl rings will be equivalent to one another which will
result in a 2:1 aryl proton resonance pattern in the 1H NMR spectra.
[figures 2.7 & 2.8].
bipyramidal
CO.
This change in symmetry is observed for all trigonal
PS3Re phosphine or phosphite compounds when reacted with
[table 2.1].
This 2:1 aryl pattern is observed for all the purple CO
complexes, and when the solution reverts back to brown, the familiar four
aryl resonances are observed.
The 31P NMR spectrum is equally revealing.
The observed 31P
resonance doublets for the PS 3 phosphorus atoms in the trigonal
bipyramidal complexes have chemical shifts between 142.6 ppm and 139.0
ppm.
But the PS 3 resonance for the six coordinate CO compounds have
chemical shifts between 116.0 ppm and 111.1 ppm.
Even though the
chemical shifts have changed position, the resonances are still doublets and
the ancillary phosphine resonance remains a doublet but the coupling
constants have decreased from an average of 245 Hz to an average of 195
Hz.
The earlier reaction of ReC13 (PMe2Ph)3 with P(SLi) 3 yielded a purple
solution which was thought to be PS 3 Re(PMe2Ph)2, but this compound
could not be isolated.
To further investigate the possibility of PS 3 Re(bis-
phosphine) compounds, P1 was reacted with chelating phosphines.
This
reasoning is further substantiated by the reported six coordinate
phosphine-thiolate Tc(III) complex by Bolzati et al.2 that incorporates
three bulky chelating ligands.
[figure 2.2].
s,
.\\ s
.
P
Figure 2.2
The newly synthesized PS 3 ReDMPE [DMPE = 1,2-(bisdimethylphosphino)ethane]
[figure 2.5] is the first structurally characterized six
coordinate PS 3 Re complex.
This compound features a chelating phosphine
which because of the "chelate effect" imposes a six coordinate coordination
about the metal center.
This purple solid is air and moisture stable and
remains unchanged in the presence of excess monophosphine such as
triphenylphosphine.
The positive (FAB) mass spectrum shows the charged PS 3 ReDMPE
mass peak with the highest intensity almost dwarfing the PS 3 Re ligandmetal core mass peak.
This in is stark contrast to earlier mass spectra of
trigonal bipyramidal complexes where the mass peak would be low in
intensity compared with the ligand-metal core peak.
The high resolution
mass spectrum had a value of 692.0122 amu for the observed and
692.0123 amu for the calculated value.
The
1H
[table 2.1].
The expected 2:1 aryl
NMR spectra was very informative.
resonance pattern was easily observed because the chelating phosphine
had no aryl protons.
[table 2.1]
The
3 1P
NMR spectra was even more
Because the complex has three phosphorus, atoms three
enlightening.
resonances were expected.
What was observed were two doublets at
117.3 and -11.3 ppm and one singlet at -18.8 ppm.
The doublet at 117.3
ppm is the coordinated PS3 resonance which is similar to the observed PS3
resonances between 111 and 116 ppm for the six coordinate PS3RePR3CO
complexes.
3 1P
The coupling constant is 223.5 Hz.
The splitting pattern of the
NMR spectra reveal that the phosphorus atoms trans to one another
are coupled through the metal center, yet the equatorial phosphine is not
coupled to either.
The crystal structure of this compound shows a distorted octahedral
geometry.
of 2.280(3)
[figure 2.5].
A
The shortest P-Re bond length is the PS 3 -Re bond
and the basal and equatorial P-Re bond lengths are 2.382(2)
A and 2.476(2) A respectively.
The (PS 3 )P-Re-P(basal) bond angle is
172.88(9)0 which is distorted compared to 1800 for a true octahedral
geometry.
The bond angle for the two sulfur atoms trans to one another in
the equatorial plane is 153.380(9) which further reveals the distortion in
the molecule from true octahedral coordination.
These six coordinate rhenium compounds that incorporate the
trianionic PS3 ligand are still d 4 , yet their
evidence of contact shifts.
1H
NMR spectra show no
It is expected that there would be two unpaired
electrons for a d 4 transition metal in a rigorous octahedral environment.
An example of a contact shifted Re(III) d 4 complex is ReC13 (PMe2Ph)3.
3
A
possible reason the PS 3 Re six coordinate complexes do not exhibit contact
shifting is because the PS 3 ligand forces a larger splitting of the 5d orbitals.
The 5d orbital of third row transition metals according to Cotton and
Wilkinson are large spatially which causes less interelectronic repulsion
when electrons are paired allowing for low-spin compounds.4
To further
investigate the magnetic properties of the PS 3 ReDMPE complex, its
magnetic susceptibility was measured.
The corrected magnetic
susceptibility of PS 3 ReDMPE at 170.2 K was 202.6 x 10-6 cm 3/mol at 1 tesla
and 61.2 x 10-6 cm 3 /mol at 4 tesla.
This translates to 0.525 BM at 1 tesla
and 0.288 BM at 4 tesla which shows this complex is weakly paramagnetic
and its paramagnetic character decreases with increased field strength and
temperature.
[table 2.5]
The complexes are essentially low spin
diamagnetic as evidenced by their 1H NMR and 31p NMR spectra.
The analogous PS 3 ReDIPHOS complex is also purple in color but has a
more complex 1H NMR spectra in the aryl region.
much like that of the PS 3 ReDMPE complex.
The 31p NMR spectra is
There are two doublets one at
119.2 ppm (PS 3 ) and another at 16.2 ppm (basal DIPHOS) and one singlet
at 2.0 ppm (equ. DIPHOS).
The coupling constant of the phosphorus atoms
coupled through the metal center is 221.0 Hz which is very close the 223.5
Hz coupling constant of PS 3 ReDMPE.
the equatorial phosphine.
Again, no cis coupling is observed for
The FAB mass spectrum also shows the
PS 3 ReDIPHOS as the mass peak with the highest intensity.
The high
resolution mass spectrum has the calculated and observed value of the H+
cation of 941.082 amu.
The similar PS 3ReTRIPHOS complex is again purple in color and has
an even more complex 1H NMR spectra due to the increased number of
aryl protons from the TRIPHOS ligand.
The 31P NMR spectra has one more
phosphorus resonance but there are only two doublets at 118.0 ppm and
14.1 ppm which is further evidence of no cis coupling.
The FAB mass
spectrum shows the mass peak of PS 3 ReTRIPHOS with a strong intensity
This
but not stronger than the ligand-metal core mass peak of 542 amu.
may be because the TRIPHOS ligand is not as rigid as DMPE and DIPHOS
therefore, allowing for a greater chance of the ligand flying off.
A bright red fraction was collected during the column purification of
the TRIPHOS complex.
This red fraction has an equally complex aryl region
in its 1H NMR spectra and has four phosphorus resonances in its 31P NMR
spectra.
Two of those resonances are doublets at 31.6 and 12.1 ppm,
where no previous coordinated PS3 resonance has been observed.
This red
fraction could possibly be a seven coordinate complex where all three
phosphorus atoms coordinate to the metal center.
Treichel and coworkers
have prepared a seven coordinate rhenium(III) isocyanide complex
ReBr3(CNp-tolyl)4 2 . [figure 2.3]
A seven coordinate complex would satisfy
the "eighteen electron rule" which could offer enough stability to
compensate for the steric strain.
This possibility will be investigated
further.
N
I
N
\\\C
N
CNO
B
Re...
_4I
Br
Br
Figure 2.3
In the reaction of P1 with tert-butylisocyanide the reaction mixture
This
becomes purple almost immediately after addition of the isocyanide.
As stated
is the case if 2.5, 1.1, or 0.9 equivalents of isocyanide are used.
earlier a low yield five coordinate compound was obtained isolated in the
preparation of the six coordinate compound, but the six coordinate
compound is the major product. The
1H
NMR spectra of PS 3 Re(CNt-Bu)2
reveals the expected 2:1 aryl region for the coordinated PS 3 ligand.
Two
aliphatic peaks are also observed which correlate to the two tert-butyl
groups.
[table 2.1]
The 31P NMR spectra has only one singlet at 109.3 ppm
which is not far from the observed 31p resonance of 111.1 ppm for the six
coordinate PS 3 RePPh3CO complex.
The FAB mass spectrum has the dual
isotope peaks of the H+ cation but also reveals the PS3Re ligand-metal core
peak and the five coordinate PS3ReCNt-Bu mass peak at much stronger
intensities.
The isocyanide ligand much like the CO ligand can dissociate
under the high energy of the fast atom bombardment.
The high resolution
mass spectrum has an observed value of 709.095 amu for the H+ cation
and a calculated value of 709.094 amu.
For those six coordinate compounds where the aryl protons are only
provided by the PS3 ligand the aryl protons can be labeled in a similar
manner as for the five coordinate compounds.
The new designations of "a"
and "b" refer to the 2:1 integrations respectively.
[figure 2.8].
Again to
further evidence the proton designations the 1H NMR spectra of
PS 3 ReDMPE was taken 31P decoupled.
[figure 2.9].
Not all chelating ligands, when reacted to P1 afforded a six
coordinate compound.
Most notably when TMEDA (tetramethylethylene-
diamine), bipy (2,2'-bipyridine), and benzil (C 6 H 5 C(O)C(O)C 6 H5), where
reacted with P1 no characterizable product was obtained.
Conclusions
It has been determined that six coordinate tris(o-mercaptophenyl)phosphine compounds of rhenium can be prepared.
A six coordinate
complex can be prepared as a PS3RePR3CO compound from existing trigonal
bipyramidal PS3Rephosphines and phosphites in a reversible reaction with
CO at room temperature.
These carbonyl complexes exist in situ or as a
solid under constant CO pressure.
PS3Re(bis-isocyanides)
are readily made
from non sterically encumbered isocyanides as evidenced in the formation
of PS 3 Re(CNt-Bu)2 with less than two equivalents of tert-butylisocyanide.
But in a similar reaction with more than one equivalent of 2,6dimethylphenylisocyanide, no evidence of a six coordinate compound was
Stable PS 3 Re(bis-phosphine) compounds can be prepared if the
found.
phosphine is supported by chelation.
The most robust of the six coordinate
compounds, as evidenced by FAB mass spectra, are the phosphine chelates.
In fact, these six coordinate complexes have the mass peak of highest
intensity.
The PS 3 Re(bis-isocyanide) has a very low intensity in its FAB
mass spectrum, and there is no mass peak for the six coordinate carbonyl
compounds.
The six coordinate complexes show no evidence of contact
shifting and the PS3 ligand exhibits a 2 to 1 aryl integration pattern in the
1H
NMR spectrum.
The "chelate effect" does not compensate enough for the strain of the
PS 3 ligand "opening up" in the case of TMEDA, bipy, or benzil.
Again, the
nitrogen donors, and also, oxygen donors, do not coordinate to the metalligand core.
The tripodal ligand-metal core can allow higher coordinations
than five if the strong field ligand is not sterically hindered, or it is
supported by chelation.
References
(1)
de Vries, N.; Cook, J.; Jones, A. G.; Davison, A. Inorg. Chem 1991, 30,
2662.
(2)
Bolzati, C.; Refosco, F.; Tisato, F.; Bandolini, G.; Dolmella, A. Inorg. Chim.
Acta 1992, 201, 7-10.
(3)
Shaw, D.; Randall, E. W. J. Chem. Soc. Chem. Comm. 1965, 82-83.
(4)
Cotton, F. A.; Wilkinson, G. Advanced Inorganic Chemistry; Fifth ed.;
John Wiley & Sons: New York, 1988, pp 632-635.
Figure
Reaction of PS3RePhosphines
2.4
and Phosphites
with
CO
CO
CH 2CI 2
-CO
brown
PR 3
R = Et, n-Bu, & Ph
royal purple
Complex
Single IR Stretch
PS 3RePEt3(CO)
1980.6 cm-1
PS 3ReP(n-Bu)3(CO)
PS 3RePPh3(CO)
1985.6
cm-1
1996.9 cm- l
Figure
2.5
ORTEP diagram of PS3ReDMPE
C(43)
C(65)
C(44)
Table
X-ray
2.2
data for the structure
PS 3 ReDMPE
determination
of
Empirical Formula
C24H28P3ReS3
Formula Weight
691.75
Crystal Color, Habit
purple,
Temperature
293 (2) K
Diffractometer
Siemens SMART/CCD
Wavelength (A)
0.71073
Crystal System
Orthorhombic
Space Group
Pca21
a (A)
15.991 (2)
b (A)
18.213 (4)
c (A)
17.454 (3)
oc (0)
90
P (o)
90
y (0)
90
Volume, (A3 )
5083.5 (14)
unknown
Z
D (calc.) (mg m - 3 )
1.808
Absorption coefficient (mm- 1)
5.228
F(000)
2720
Crystal size (mm)
0.32 x 0.28 x 0.15
Theta range (0)
1.69 to 23.26
Limiting indicies
-17 < h < 17, -20 < k < 11,
-19 < 1 < 17
Reflections collected
19777
Independent
reflections
6996 (Rint = 0.0352)
Absorption
correction
None
Refinement
method
Full-matrix least-squares on F
Table 2.2 continued.
Data/restraints/parameters
6992/1/546
Goodness of Fit on F2
1.163
Final R indices [I.2o(I)]
R1 = 0.0352, wR2 = 0.0683
R indices (all data)
R1 = 0.0372, wR2 = 0.0703
Extinction coefficient
0.00025 (2)
Max difference peak (eA - 3 )
1.091
Min difference peak (eA - 3 )
-0.866
Table
2.3
Bond lengths (A) and angles (0) for
PS 3 ReDMPE
Atom
Atom
Distance (A)
Atom
Atom
Re (1)
P (1)
2.280 (3)
C (21)
(22)
1.373 (12)
Re (1)
s (13)
2.322 (3)
C (21)
(26)
1.427 (12)
Re (1)
S (11)
2.333 (2)
C (22)
(23)
1.408 (13)
Re (1)
S (12)
2.383 (2)
C (23)
(24)
1.388 (14)
Re (1)
P (2)
2.382 (2)
C (24)
(25)
1.375 (14)
Re (1)
P (4)
2.476 (2)
C (25)
(26)
1.398 (13)
P (1)
: (41)
1.815
(9)
C (41)
(42)
1.400 (12)
P(1)
C (21)
1.809 (9)
C (42)
(43)
1.363 (12)
P(1)
Z (61)
1.845 (9)
C (43)
(44)
1.379 (14)
S (11)
Z (46)
1.782 (9)
C (44)
(45)
1.377 (14)
S (12)
S (26)
1.778 (8)
C (45)
(46)
1.401 (13)
S (13)
5 (66)
1.784 (9)
C (46)
(41)
1.408 (12)
P (2)
c (28)
1.807 (10)
C (61)
(62)
1.380 (13)
P (2)
5 (27)
1.823 (11)
C (62)
(63)
1.382 (12)
P (2)
C (2)
1.849 (10)
C (63)
(64)
1.375 (13)
P (4)
5 (47)
1.807 (10)
C (64)
(65)
1.353 (14)
P (4)
C (48)
1.831 (9)
C (65)
(66)
1.403 (13)
(4)
C (4)
1.844 (9)
C (66)
(61)
1.374 (13)
(2)
C (4)
1.521 (14)
Distance (A)
Atom
Atom
Atom
Angle (0)
172.88 (9)
(61)
(1)
Re (1)
109.9
S (11)
84.19
(9)
(26)
(21)
C (22)
119.7 (8)
Re (1)
S (12)
82.36 (9)
(21)
(22)
C (23)
121.1
(9)
P (1)
Re (1)
S (13)
83.08 (8)
(22)
(23)
C (24)
119.2
(9)
P (1)
Re (1)
P (4)
(8)
(23)
(24)
C (25)
120.0 (10)
P (2)
Re (1)
S (11)
101.57 (9)
(24)
(25)
C (26)
121.9
P (2)
Re (1)
S (12)
93.91 (8)
(25)
(26)
C (21)
118.0 (8)
P (2)
Re (1)
S (13)
89.48 (9)
(46)
(41)
C (42)
119.0 (8)
P (2)
Re (1)
P (4)
79.94 (9)
(41)
(42)
C (43)
121.9
S (11)
Re (1)
P (4)
83.14
(8)
(42)
(43)
C (44)
118.9 (9)
S (11)
Re (1)
S (13)
103.25
(9)
(43)
(44)
C (45)
121.2
S (13)
Re (1)
S (12)
98.37 (9)
(44)
(45)
C (46)
120.5 (9)
S (12)
Re (1)
P (4)
78.37 (8)
(45)
(46)
C (41)
118.4 (9)
S (11)
Re (1)
S (12)
153.38
(9)
(66)
(61)
C (62)
120.9 (9)
S(13)
Re (1)
P (4)
168.62
(9)
(61)
(62)
C (63)
121.5
P (1)
C (41)
C (42)
126.9
(7)
(62)
(63)
C (64)
117.0 (9)
P (1)
C (41)
C (46)
113.8
(7)
(63)
(64)
C (65)
122.4 (10)
P (1)
C (21)
C (22)
128.5
(7)
(64)
(65)
C (66)
120.7 (9)
P (1)
C (21)
C (26)
111.7
(6)
(65)
(66)
C (61)
117.5 (9)
P (1)
C (61)
C (62)
124.2 (8)
(11)
(46)
C (41)
122.1 (7)
P (1)
C (61)
C (66)
114.9 (7)
(11)
(46)
C (45)
119.5
C (21)
P (1)
C (41)
113.4
(4)
(12)
(26)
C (21)
122.8 (6)
C (21)
P (1)
C (61)
105.3
(4)
(12)
(26)
C (25)
119.2 (7)
C (41)
P (1)
C (61)
104.3 (4)
(13)
(66)
C (61)
122.4 (7)
C (21)
P (1)
Re (1)
111.8
(3)
(13)
(66)
C (65)
120.1 (7)
C (41)
P (1)
Re (1)
111.6
(3)
C (46)
S (11)
Re (1)
107.6 (3)
Atom
Atom
Atom
Angle (°)
P (1)
Re (1)
P (2)
P (1)
Re (1)
P (1)
105.11
(4)
(10)
(9)
(9)
(9)
(7)
C (26)
S (12)
Re (1)
105.9
(3)
C (66)
S (13)
Re (1)
107.5 (3)
Re (1)
P(4)
C (47)
122.1 (3)
Re (1)
P (4)
C (48)
119.7 (3)
Re (1)
P (4)
C (4)
108.0 (3)
Re (1)
P (2)
C (27)
120.3 (4)
Re (1)
P (2)
C (28)
113.5 (3)
Re (1)
P (2)
C (2)
111.5
C (28)
P (2)
C (27)
103.6
(5)
C (28)
P (2)
C (2)
100.6 (5)
C (27)
P (2)
C (2)
105.1 (5)
C (47)
P (4)
C (48)
99.8 (5)
C (47)
P (4)
C (4)
102.2
C (48)
P(4)
C (4)
102.2 (4)
(5)
(3)
Table
Atomic
coordinates
displacement
[x
parameters
104]
2.4
and
equivalent
isotropic
[A2 x 103] for PS 3 ReDMPE.
U(eq) is defined as one third of the trace of the orthogonalized Uij tensor.
Atom
X
Y
Z
U(eq)
Re (1)
6776 (1)
3760 (1)
5699 (1)
18 (1)
S (11)
7112 (1)
2572 (1)
5306 (2)
24(1)
S (12)
6578 (1)
5042 (1)
5489 (1)
26 (1)
S (13)
5708 (2)
3576 (2)
6579 (1)
24 (1)
P (1)
5747 (2)
3672 (1)
4800 (2)
17 (1)
P (2)
7731 (2)
3938 (2)
6730 (1)
23 (1)
P (4)
8055 (1)
4083 (1)
4973 (1)
22 (1)
C (2)
8818 (6)
4033 (6)
6382 (6)
32 (3)
C (4)
8812 (5)
4485 (5)
5650 (6)
30 (2)
C (21)
5669 (5)
4498 (5)
4227 (5)
18 (2)
C (22)
5310 (5)
4586 (5)
3519 (5)
20 (2)
C (23)
5259 (6)
5282 (6)
3172 (6)
32 (3)
C (24)
5577 (6)
5889 (6)
3556 (6)
30 (2)
C (25)
5945 (5)
5804 (6)
4262 (6)
31 (3)
C (26)
6021 (5)
5117
(5)
4611 (5)
14 (2)
C (27)
7787 (6)
3272 (6)
7508 (6)
40 (3)
C (28)
7597 (6)
4805 (5)
7218
(6)
34 (3)
C (41)
5850 (5)
2843 (5)
4232
(5)
18 (2)
C (42)
5338 (5)
2621 (5)
3624 (5)
24 (2)
C (43)
5433 (5)
1957 (5)
3274 (5)
24 (2)
C (44)
6050 (6)
1489 (6)
3531 (6)
32 (3)
C (45)
6553 (6)
1674 (5)
4142 (6)
30 (3)
C (46)
6466 (5)
2356 (5)
4505 (5)
20 (2)
C (47)
8046 (6)
4752 (6)
4208 (6)
35 (3)
C (48)
8670 (6)
3357 (5)
4517 (6)
30 (2)
C (61)
4721 (5)
3577 (5)
5273 (7)
18 (2)
C (62)
3969 (6)
3528 (5)
4888 (6)
23 (2)
C (63)
3222 (5)
3434 (5)
5274 (7)
26 (2)
C (64)
3260 (6)
3403 (6)
6060 (7)
31 (3)
C (65)
3989 (6)
3455 (5)
6449 (6)
27 (2)
C (66)
4749 (6)
3543 (5)
6059 (5)
20 (2)
100
Figure
Reactions
of P1
101
2.6
with chelating
phosphines
P1
P(SLi) 3 +
THF
ReBr 3 (tht) 3
refluxed
E
E
E=SorO
P1
+
DMPE
THF
refluxed
purple
P1
THF
+ DIPHOS
refluxed
royal purple
P1
THF
+ TRIPHOS
refluxed
royal purple
102
Figure
Reaction
of P1
103
with
2.7
t-butylisocyanide
P1
P(SLi) 3
ReBr 3 (tht) 3
THF
refluxed
E
E=SorO
THF
P1
+
CNt-Bu
refluxed
C
7"-
IIII
C
N
royal purple
* only product if excess of isocyanide is used
104
brown
Table
2.5
Magnetic Susceptibility data for PS 3 ReDMPE
105
Magnetic Susceptibility of PS3ReDMPE
Xp = Xm - XD
XD = -354.26 x 10-6 cm 3/mol
At 1 tesla and 170.2 K
At 4 tesla and 170.2 K
Zm = -152x10 -6 cm 3/mol
Xm = -293x10-6 cm 3/mol
3
Xp = 202.6x10- 6 cm /mol
Xp
L = 2.828(XpT) 1/2
g = 2.828(xpT)1/2
kl = 0.525 BM
t = 0.288 BM
106
=
61.26x10- 6 cm 3/mol
Figure
Hydrogen
labeling
for
107
2.8
six coordinate
structures
Hydrogen Labeling for Six
Coordinate Structures
C)
Cou
('U
. H3a
H4a
H 2a
H1a
H 3 a & H2b
H 4a
H3b
Hlb
ryTETT171
-rr-
II
I.
6.07
2.55
1H
I
I
I.
5.08
17.52
4.85
2.43
NMR of PS3 ReDMPE aryl region
108
Figure
Hydrogen
six
labeling for
coordinate
109
2.9
3 1P
decoupled
structures
-H
3a
U)
ul
cu
LU
H 3 a & H2b
H 2a
Hia
L
r -.
U)J4
I
)i
(n
(n
H4b
Hlb
(I
H3b
Vt
,-,..
IIII
I
8
III
~ I II
8.6
I
I
I
I
8.4
34.11
I
I
I
8.2
I
I I
II I I I
I I
8.0
I I
I
I I
I I I I
I I
I I
7.6
7.8
29.59
__
1H
--
I I
NMR of PS3 ReDMPE
110
3 1P
I I I
7.4
I I I I
I
I I
7.2
35.095
decoupled
I I I I I I
I
JIM"-k h-li
vw-mir"-,r
___ _~ 11-ow-r-
7.0
4i.
I I
6.8
Acknowledgments
I would like to thank all the people who have made my time as a
graduate student at MIT educational, enjoyable, and productive.
First and
foremost, I would like to thank Alan Davison for his patience and insight.
Although I'm sure I contributed to a few gray hairs, I appreciate the
opportunity and freedom to do interesting chemistry.
I also thank the
GEM consortium which provided my fellowship.
I thank the members of the Davison group past and present:
Jess,
Bob, Terry, Jed, Melissa, Chris, Ryan, Ann, and Evan, who have aided me
with their knowledge and broadened my perspectives with their many
different opinions.
I would like to thank Dr. Bill Davis for collecting and solving my
crystal structures.
The Spec Lab staff, Jeanne, Debbie, Jim, and Jeff, has
been an enormous help in particular with the phosphorus decoupled
proton spectra.
In addition, Li Li has been invaluable collecting the mass
spectra especially when I absolutely had to have it.
I also thank the Black Graduate Students Association (BGSA) which
has provided me with support, friendship, and shelter when needed most.
I will not forget the Ebony Affairs, barbeques, and trips to Talbot House.
Finally I want to thank Chenita for listening to me, giving me advice,
and being a very good friend.
111
Biographical
Note
The author was born at 4:30 pm on April 11, 1971 (Easter Sunday) in
Greensboro, NC to Sylvester and Millicent Daughtry.
He graduated from
Dudley High School in Greensboro, NC in 1989 and attended Morehouse
College.
While at Morehouse, he majored in chemistry, spent three
summers as a research intern with NASA, and conducted undergraduate
research under Dr. Morris Waugh.
After graduating from Morehouse in
May 1993, he worked for Union Carbide as a research assistant during the
summer of 1993 and then came to work for Alan Davison.
112