National Journal of Chemistry, 2006, Volume 23,352-367
‫المجلد الثالث والعشرون‬-6002-‫المجلة القطرية للكيمياء‬
New rhenium and zinc complexes of
2-formylpyridine N(4)-phenylthiosemicarbazone
Mohamad Jaber Al-Jeboori
Department of Chemistry, College of Education, Ibn Al-Haitham, University of Baghdad,
P.O. 4150, Adhamiyah, Baghdad, Iraq.
e-mail:mohamadaljeboori@yahoo.com
(NJC)
(Received on 11 / 4 / 2006 )
(Accepted for publication on 19/8 / 2006 )
Abstract
A New rhenium(V)-oxo, rhenium(III) and Zn(II) complexes [ReOCl2(L)],
[Re(L)2]Cl
and
[ZnCl2(HL)](where;
HL
=
2-formylpyridine-N(4)phenylthiosemicarbazone) have been synthesised and characterised. [ReOCl3(PPh3)2]
and [ReO4]- in presence of PPh3 have been used as a starting material to prepare
rhenium(V)-oxo and rhenium(III) complexes, while ZnCl2 is used to prepare the zinc
complex. The new complexes have been characterised by microanalyses, IR, (UV-Vis.),
1
H, 13C NMR, mass spectroscopy and molar conductance. These studies show the Re(III)
ion is in a distorted octahedral environment with two tridentate deprotonated
thiosemicarbazone binding as monoanionic ligands through the sulfur, pyridyl nitrogen
and azamethinic nitrogen in which the complex does not result in isomeric mixtures. The
geometry about Re(V) ion is a distorted octahedral environment with one tridentate
deprotonated monoanionic ligand, two chloro ligands and oxo moiety. The NMR studies
(1H, 13C) of [ReOCl2(L)] show the existence of the complex in two isomers in solution.
On the other hand the geometry about Zn is a trigonal bipyramidal with one tridentate
ligand in thion form, and two chloro ligands.
‫الخالصة‬
‫) ذات الصيغ العامة‬II( ‫) و الزنك‬III( ‫) اوكسو و رينيوم‬V( ‫تم تحضيرو تشخيص معقدات جديدة للرينيوم‬
: ‫[ على التوالي حيث‬ZnCl2(HL)]‫[و‬Re(L)2]Cl ‫[و‬ReOCl2(L)]
‫[بوجود ثالثي فنيل‬ReO4]- ‫[ و‬ReOCl3(PPh3)2] ‫ تم استخدام‬.‫ ثايوسميكاربازون‬-N4‫فورمايل بردين‬-6 =HL
‫ بينما تم استخدام كلوريد الزنك كمادة‬, )III( ‫) اوكسو والرينيوم‬V( ‫الفوسفين كمواد اولية في تحضير معقدات الرينيوم‬
‫ و‬IR ‫ تم تشخيص المعقدات الجديدة بوساطة التحليل الدقيق للعناصر و طيف ال‬. ‫اولية عند تحضير معقد الزنك‬
‫ بينت هذه‬. ‫ و طيف الكتلة و التوصيلية الموالرية‬1H, 13C ‫ و طيف الرنين النووي المغناطيسي‬UV-Vis ‫طيف ال‬
352
National Journal of Chemistry, 2006, Volume 23,352-367
‫المجلد الثالث والعشرون‬-6002-‫المجلة القطرية للكيمياء‬
‫) هو ثماني السطوح المشوه حيث تتناسق جزيئتان من اللكيند‬III( ‫الدراسات ان الشكل الفراغي حول ايون الرينيوم‬
‫ثالثية االرتباط بشكل انيوني من خالل ذرة الكبريت و نتروجين مجموعة البريدايل و نتروجين مجموعة االيزوميثانيك‬
‫) شكل ثماني السطوح المشوه من خالل‬V( ‫ كذلك يظهر معقد الرينيوم‬. ‫حيث يظهر المعقد ايزومر واحد في المحلول‬
‫ارتباط ليكند واحد بشكل انيوني من خالل ذرة الكبريت و نتروجين مجموعة البريدايل و نتروجين مجموعة‬
1
H,
13
C ‫ بينت دراسات الرنين النووي المغناطيسي‬. ‫االيزوميثانيك و ذرتي كلور باالضافة الى مجموعة االوكسو‬
‫ من جهة اخرى بينت الدراسات اعاله ان الشكل‬. ‫[ تواجده بشكل ايزومرين في المحلول‬ReOCl2(L)] ‫للمعقد‬
‫الفراغي حول ايون الزنك هو ثنائي الهرم المثلث حيث ترتبط جزيئة واحدة من اليكند ثالثية السن بشكل ثايون مع‬
. ‫مجموعتين من الكلور‬
Thiosemicarbazones (tautomeric forms
Introduction
Thiosemicarbazones compounds
Ia, Ib and Ic) are versatile ligands which
exhibit a wide range of biological
can coordinate as neutral ligands or in
activity, which is dependent upon the
their
chemical nature of the moiety attached
metal complexes have been studied
to the C-S carbon atom.[1] In particular
chemically
heterocyclic thiosemicarbazones display
crystallography.[6]
very interesting biological properties,
additional
such as antitumour, antibacterial and
phosphines, amines, hydroxyl or thiol
antifungal activity.[2] The activity of the
group at the residue R1 are of special
uncomplexed thiosemicarbazone can be
interest since they can coordinate in a
increased significantly by the formation
tridentate manner which results in a
of metal complexes, as has been
significant increase of the stability of the
demonstrated previously in literatures.[3-
complexes.[7]
deprotonated
form.
and
Numerous
by
Ligands
donor
groups
such
5]
S
R
1
2
3
C N N C NH2
1
R
H
HS
R
4
1
C N 2N 3N 4NH2
1
1b
1a
353
2
C N N 3N
1
R
HS
R
1
R
X-ray
H
1c
4
NH
with
as
National Journal of Chemistry, 2006, Volume 23,352-367
Rhenium
complexes
with
‫المجلد الثالث والعشرون‬-6002-‫المجلة القطرية للكيمياء‬
prepared by a reductive ligand exchange
thiosemicarbazones are rare due to their
starting
stability. The first structural report on
[ReO4]-.[8] A recent publication reported
such compounds was published dealing
that, reduction of the metal ion can be
with cationic ReIII compounds of the
avoided and stable rhenium(V) oxo
general composition [Re(L)2]+, where: L
complexes
represents a tridentate 2-acetylpyridine
pyridineformamidethiosemicarbazones
which the two nitrogen atoms of the
(HL2) are used instead of HL1. X-ray
hydrazones unit bind to each one of the
crystallography showed the geometry
rhenium atoms.
about Re(V) is a distorted octahedral.
They have been
from
[ReOCl3(PPh3)2]
are
formed
when
or
2-
[9]
obtained by Electron-Impact (EI), while
Experimental
Reagents were purchased from
rhenium complexes were recorded on a
Fluka and Redial – Dehenge Chemical
VG autospec micromass spectrometer
Co. I.R spectra were recorded as (KBr)
operating under fast atom bombardment
discs using a Shimadzu 8300 FTIR
conditions (nitrobenzyl alcohol matrix).
spectrophotometer in the range (4000-
The spectra were recorded at University
400) cm-1. Electronic spectra of the
of Free Berlin/Germany, and Queen
prepared compounds were measured in
Mary,
the region (200-900) nm for 10-3 M
Nuclear magnetic resonance spectra (1H,
13
solutions in (DMSO) at 25C using a
University
of
London/UK.
C-NMR) were acquired with Brucker
Shimadzu 160 spectrophotometer, with
400, and Jeol EX400, EX270 Hz
1.0000.001cm matched quartz cell.
spectrometers in DMSO-d6. The spectra
were recorded at University of Free
Mass spectrum for the ligand was
354
‫المجلد الثالث والعشرون‬-6002-‫المجلة القطرية للكيمياء‬
National Journal of Chemistry, 2006, Volume 23,352-367
Berlin/Germany,
and
Queen
University of London/UK.
Mary,
[ReOCl2(L)]
complex.
Elemental
[ReOCl3(PPh3)2] (0.162g, 0.194mmol)
microanalyses were performed on a
was added to a mixture of [HL] (0.05g,
(C.H.N.) analyser from Heraeus (Vario
0.195mmol) in (20mL) MeOH.
EL),
Free
mixture was heated at reflux under an
Berlin/Germany. The chloride contents
atmosphere of nitrogen for (2-3) hours,
for complexes were determined by using
during which time the colour of the
potentiometer titration method on (686–
reaction mixture became brown in
Titro processor– 665Dosimat–Metrohm
colour. The mixture was allowed to cool
Swiss).Electrical
conductivity
to room temperature, and filtered off. A
measurements of the complexes were
red-brick solid was collected, washed
recorded at 25C for 10-3 M solutions of
with (5mL) cold MeOH and (5mL) Et2O.
the samples in (DMSO) using a PW
Yield (0.06g, 58%) of [ReOCl2(L)] .
9526 digital conductivity meter.
[Re(L)2]Cl complex. [ReOCl3(PPh3)2]
Synthesis
(0.162g, 0.194mmol) was added to a
[ReOCl3(PPh3)2] was prepared by a
mixture of HL (0.1g, 0.39mmol) in
literature procedure.[10] The ligand [HL]
(35mL) MeOH. The mixture was heated
was
conventional
at reflux under an atmosphere of
procedure[11]: 2-formylpyridine (3.0g,
nitrogen for 4 hours, during which time
28mmol) and 4-phenylthiosemicarbazide
the colour of the reaction mixture
(4.65g,
became brown in colour. The mixture
at
the
University
synthesised
28mmol)
by
were
of
added
to
to
room
heated at reflux under an atmosphere of
temperature, and filtered off.
The
nitrogen for 4 hrs. The reaction mixture
solvent of the filtrate was reduced under
was
room
vacuum to ca. (6mL), and a black-brown
A crystalline precipitate
solid was formed upon addition of
methanol (20mL).
allowed
temperature.
to
was
The mixture was
cool
to
allowed
to
cool
The
formed which was collected by filtration
(20mL) Et2O.
and washed with a small amount of cold
recrystalised from CH2Cl2/n-hexen, to
methanol and copious quantities of
give
diethyl ether to give the ligand as large
compound.
beige crystals, 5.4g (75%).
355
(0.091g,
The precipitate was
63%)
of
the
title
National Journal of Chemistry, 2006, Volume 23,352-367
‫المجلد الثالث والعشرون‬-6002-‫المجلة القطرية للكيمياء‬
from
in colour, and a precipitate was formed.
[NH4][ReO4] (0.1 g,
The solid was collected by filtration,
0.373 mmol) was added to a mixture of
washed with methanol (5mL) and dry
methanol (20mL), triphenylphosphine
ethyl ether (10mL), and dried under
(0.4g, 1.52 mmol) and HCl (37 %)
vacuum to give 0.063g, (82%) yield of
(1mL). The mixture was heated at reflux
the title compound.
under an atmosphere of argon for 1 hour.
Results and Discussion
The mixture was allowed to cool to room
Synthesis of the ligand
temperature, and triethylamine (1.5mL),
The Schiff base ligand was prepared by
(HL) (0.19g, 0.74mmol) in (12 mL)
the
methanol was added. The mixture was
carboxaldehyde
heated at reflux under an atmosphere of
phenylthiosemicarbazide
nitrogen. The mixture was filtered hot
The
and the solvent was reduced to about (8
elemental
mL) by evaporation under reduced
(Table2), (U.V-Vis) (Table3), mass
pressure. The mixture was left to stand
spectroscopy, 1H and
Synthesis
of
[NH4][ReO4].
0
[Re(L)2]Cl
at 4 C overnight.
condensation
ligand
of
with
was
pyridine-2the
(Scheme1).
characterised
analysis
(Table1),
13
4-
by
IR
C NMR spectra
The black-brown
(Table4). The IR spectrum (Figure1-1)
crystals were collected by filtration, and
showed several strong bands at (1596)
washed with cold methanol (1mL) and
and (1550, 1496, 1465)cm-1 assigned for
Et2O (5 mL) to give [Re(L)2]Cl (0.1g,
υ(C=N) imine and [υ(C=N) pyrdiyl +
37%).
υ(C=C)] stretches respectively.
Analytical data was consistent
The
with the compound synthesised from
bands at (3305) and (3120) cm-1 were
[ReOCl3(PPh3)2].
assigned to υ(N(4)-H) and υ(N(3)-H)
[ZnCl2(HL)] complex. To a stirred
respectively. The latter band indicated
solution of [HL] (0.05g, 0.195 mmole),
the presence of the ligand in the thion
in methanol (20 ml) was added slowly a
form.[12] The spectrum showed no band
solution of ZnCl2 (0.026g, 0.195mmole)
around ca. (2550)cm-1 that could be
in
related to υ(S-H).
methanol
(10ml). The
resulting
The (U.V.-Vis)
mixture was heated under reflux for 3
spectrum exhibits a highly intense
hours under nitrogen atmosphere, during
absorption peak at (211 nm) (47393cm-1)
which time the solution became a yellow
(max =4410 molar-1cm-1) and (328nm)
356
National Journal of Chemistry, 2006, Volume 23,352-367
‫المجلد الثالث والعشرون‬-6002-‫المجلة القطرية للكيمياء‬
13
(30407cm-1) (max =1720 molar-1cm-1)
C=N(2)) imine.
which were assigned to (*) and
showed a signal at chemical shift
respectively.[13]
(176.34)ppm was attributed to (C=S).
Whilst the peak at (391nm) (25575cm-1)
The EI(+) mass spectrum of the ligand
(max =334 molar-1cm-1) was assigned to
showed the parent ion peak at m/z= 256
(n*)
transitions
1
charge transfer.
C NMR spectrum
(M)+, and the following fragments; 178=
H NMR spectrum in
(DMSO-d6) (Figure2) displayed signals
(M-py)+,
at
136= [M-{py+HC=N-NH}]+, 92= [M-{
chemical
shifts
(12.11)
and
[M-{py+HC=NH}]+,
150=
(10.33)ppm attributed to δ(N(3)-H) and
py+HC=N-NH-C=S}]+,
δ(N(4)-H) respectively.
py+HC=N-NH-C=S-NH}]+.[14]
The chemical
77=
[M-{
shift at (8.12)ppm assigned for δ(H-
3
4
2
H2N
H
N
NH
MeOH , Reflux
C NH
S
+
6
5
1
N
1
N
2
O
H
N 7 H 8
3 C N
4
S
9
10
11
13
12
Scheme (1) The synthesis route of the ligand
(Scheme2). Reduction of Re(V)-oxo to
Synthesis of the complexes
New
rhenium
and
zinc
Re(III) and the formation of the cationic
complexes
are
[Re(L)2]Cl complex as a black brown
of
solid is observed, when an excess of
[ReOCl3(PPh3)2] with one equivalent of
[HL] is used and the reaction mixture is
the tridentate ligand [HL] in MeOH at
heated under reflux for a prolonged time.
reflux and under nitrogen atmosphere
The reduction of the metal atom is most
gave the monomeric neutral complex
probably due to the liberated PPh3. This
[ReOCl2(L)] as a red brick solid
has been observed previously for many
thiosemicarbazone
synthesised.
The
reaction
357
National Journal of Chemistry, 2006, Volume 23,352-367
reactions
starting
‫المجلد الثالث والعشرون‬-6002-‫المجلة القطرية للكيمياء‬
from
perrhenate by the addition of HCl and
[ReOCl3(PPh3)2],[15] including exchange
PPh3 as the reducing agent. Whilst the
reactions with ligands of the type
reaction
[HL2][7]. However, the nature of the
equivalent of the tridentate ligand [HL]
incoming ligand is essential to control
in MeOH at reflux and in the presence of
the composition and oxidation state of
PPh3 and HCl gave intractable black
the metal atom in the products. Whereas
solid (see Scheme2). On the other hand
exclusively rhenium(III) cations of the
[ZnCl2(HL)] was obtained as a neutral
[Re(L)2]+
composition
of
[ReVIIO4]-
with
one
and
yellow solid from the reaction of ZnCl2
be
with [HL] in MeOH at reflux and under
acetylpyridine
nitrogen atmosphere. These complexes
thiosemicarbazones [HL2] are used.[8]
are stable in solution and in solid state.
The reaction with the corresponding 2-
The molar conductance of the complexes
pyridineformamide derivatives [HL1][8]
[ReOCl2(L)]
or
N(4)-
(DMSO) lies in the (15.3-12.5) S cm2
be
mole-1 range, indicating their non-
decomposition
isolated
with
products
when
could
2-formylpyridine
phenylthiosemicarbazone
can
and
[ZnCl2(HL)]
performed stepwise (see Scheme2) and
electrolytic
oxorhenium(V) intermediates can be
conductance of [Re(L)2]Cl in (DMSO) is
isolated in reasonable
yields. This
(51.3) S cm2 mole-1, indicating its
behaviour demonstrated that, the nature
electrolytic nature with (1:1) ratio,[17]
of substituents on -N(2) and/or -N(4) of
(Table3). The analytical and physical
the thiosemicarbazones is crucial to
data (Table1) and spectral data (Tables
stabilize metal atoms in higher oxidation
2, 3 and 4) are compatible with the
states.[16] Significantly in terms of the
suggested structures (Figure3).
possible
for
atom numbering for the complexes
[Re(L)2]+
described is the same as that employed
application
radiopharmaceuticals,
the
complex was prepared directly from
nature.
While
in
in the ligand synthesis (Scheme1).
358
the
The
‫المجلد الثالث والعشرون‬-6002-‫المجلة القطرية للكيمياء‬
National Journal of Chemistry, 2006, Volume 23,352-367
[ReOCl3 (PPh 3)2 ]
eO
at
N2
H,
a tm Re fl
o s ux ,
ph
H
ere L
M
H
,R
m
os
x,
+
2H
L
2
e
eO
er
M
lu
ph
N
ef
H
Re
S
N
H
H
Re
N
N
N
H L, PPh3
MeOH , Reflux,
N 2 atmosphere
N O N N
Cl
N
N
H
S
NH
N
S
HN
eO
H
,R
ef
ef
m
at
,R
H
M
h3
N
P
eO
,P
e
L
er
,H
ph
x
lu
os
2
N
2 a tm
lu
x
os , 2
ph H
er L ,
e PP
h
M
X
3
Cl
[ReO 4 ]-
Scheme (2) The synthesis route of rhenium complexes
Table (1) Analytical and physical data of the ligand and its complexes
Compound
[HL]
[Re(L)2]Cl
[ReOCl2(L)]
[ZnCl2(HL)]
m.poc
Colour
Yield%
White
199
75
Dark brown
175
63
>300
Red brick
>300
Yellow
58
82
Found, (calc.)%
S
N
C
H
(60.91)
60.50
(42.76)
43.19
(29.60)
29.50
(39.87)
39.32
(4.72)
4.89
(2.76)
3.01
(1.91)
1.65
(2.83)
2.40
(21.86)
21.90
(15.34)
14.97
(10.62)
10.23
(14.31)
14.22
(12.55)
12.77
(8.78)
8.61
(6.08)
5.89
(8.19)
8.20
Cl
----(4.85)
4.73
(13.44)
14.02
(18.11)
18.43
(Calc.) : Calculated
IR Spectra
1600 cm-1, indicating coordination of the
The IR bands most useful of determining
imine nitrogen N-(2). The spectrum of
the
of
the ligand shows the thioamide IV band,
coordination are shown in (Table2).
which at 870cm-1, and it shifts to higher
The
[ReO(L)Cl2]
energy and appears at 891cm-1 on
(Figure1-2)shows the υ(C=N) band of
coordination of the ligand. The absence
the ligand at 1596 cm-1 undergoes small
of (N(3)-H) band at 3120cm-1, indicates
shifts to higher frequency and appear at
the coordination of the ligand in thiol
thiosemicarbazones
IR
spectrum
of
mode
359
‫المجلد الثالث والعشرون‬-6002-‫المجلة القطرية للكيمياء‬
National Journal of Chemistry, 2006, Volume 23,352-367
form. The spectrum shows band at
coordination of the ligand to Zn(II) ion
979cm-1 characteristic of the υ(Re=O)
in thion form.
stretching,[18] additional evidence for
Electronic Spectra
coordination of the imine nitrogen is the
The (U.V-Vis) spectrum of the complex
presence of υ(M-N) band at 432cm-1.[19]
[ReOCl2(L)] displayed absorption peaks
The IR spectrum of the [Re(L)2]+
at
complex
demonstrates
molar-1cm-1) and a shoulder at (338nm)
symmetric coordination of the two
(29585cm-1) ( max =390 molar-1cm-1)
thiosemicarbazone ligands through the
assigned for ligand field. The peak at
nitrogen atoms of pyridine, azomethine
(420nm) (23809cm-1) ( max =225 molar-
groups and sulfur atoms, similar to the
1
Re(III)
(3T1g(p)  3T1g).
(Figure1-3)
complex
with
anionic
(216nm)(46296cm-1)(
max =4420
cm-1) assigned to (d-d) transition type
This result is in
thiosemicarbazone ligand, for which X-
agreement with that reported for oxo-
ray analysis
Re(V) with octahedral geometry.[21,
confirmed a distorted
octahedral geometry.
The spectrum
[Re(L)2]Cl
shows no band related to the υ(Re=O).
1
at 3126cm-1, indicates the coordination
The peak at (390nm)
(25641cm-1) (max =1570 molar-1cm-1)
was assigned to charge transfer. Whilst
4)shows the imine υ(C=N) band of the
ligand at 1596 cm
four
) ( max =4410 molar-1cm-1) assigned to
ligand field.
The IR
spectrum of [Zn(HL)Cl2] (Figure1-1
exhibits
absorption peaks at (215nm) (46511cm-
Moreover the absence of (N(3)-H) band
of the ligand in thiol form.
complex
22]
the peaks at (451nm) (22172cm-1) ( max
shifts to higher
=788 molar-1cm-1) and a broad peak at
-1
frequency and appear at 1620 cm ,
(605nm) (165281cm-1) ( max =195
indicating coordination of the imine
molar-1cm-1) were attributed to d-d
nitrogen N-(2). This increase is due to
transitions type (1T2g  1A2g) and (1T2g
weaker coordination to the central ion in
 1T1g) respectively. This result is in
comparison with rhenium.[20] The band
agreement with that reported for Re(III)
at 3126 cm-1 was attributed to ( N(3)-H)
complexes with a distorted octahedral
in the IR spectrum of the ligand is still
geometry.[23] The [ZnCl2(HL)] complex
exist in the complex spectrum, and
shows three absorption peaks at (215nm)
appeared at 3197cm-1 indicating the
360
‫المجلد الثالث والعشرون‬-6002-‫المجلة القطرية للكيمياء‬
National Journal of Chemistry, 2006, Volume 23,352-367
(46511cm-1) (max =4410 molar-1cm-1)
belong to d10 system, the peak at
and (329nm)(30395cm-1) (max =1844
(408nm) (24509cm-1) (max =210 molar-
molar-1cm-1) assigned to ligand field.
1
cm-1) was assigned to charge transfer.
Since the metal ion of the complex
Table (2) I.R spectral data (wave number ) cm-1 of the ligand [HL] and it’s
complexes
Compound
[HL]
[Re(L)2]Cl
(N(4)-H)
(C-H)
 (N-NH)
3305(w)
3126
2947(w)
---3166
3043,
2927
(C=N)
imine
1597(s)
1600
Additional
(C=C) (N-N) (C-S)
(M-N)
peaks
 (C=N)
1550(sh)
995 870
756, 690
1496(sh)
(C-H)
Out of plane
1004 903
1523
1458
1022 891
[ReOCl2(L)]
---3262
[ZnCl2(HL)]
3259
3197
3066,
2927
3028
1596
1554
1492,
1458
1612
1558
1492,
1446
1010 906
756,
690(C-H)
Out of plane
979
(Re=O).
432(w) 752,
690(C-H)
Out of
plane.
759, 694
415(w) (C-H)
Out of
plane.
428(w)
Recorded as KBr: s: strong, m: medium, w: weak.
Table (3) Electronic spectral data and conductivity measurement of [HL] and its metal complexes
Compound
[HL]
[Re(L)2]Cl
[ReOCl2(L)]
[ZnCl2(HL)]

nm
211
328
391
215
390
451
605
216
338
420
215
342
409

cm-1
max
–1
-1
(molar . cm )
47393
30407
25575
46511
25641
22172
16528
46296
29585
23809
46511
30395
24509
4410
1720
334
4420
1570
786
195
4420
390
270
4410
1844
210
361
ΛM(Ω-1
cm2mol1)
Ratio
51.3
(1:1)
15.8
Neutral
12.5
Neutral
National Journal of Chemistry, 2006, Volume 23,352-367
‫المجلد الثالث والعشرون‬-6002-‫المجلة القطرية للكيمياء‬
Figure 1 (IR) spectra (cm-1) of:
(1-1) The ligand [HL]
(1-2) The complex [ReO(L)Cl2]
(1-3) The complex [Re(L)2]Cl
(1-4) The complex [Zn(HL)Cl2
and the following fragments; 459= (M-
Mass Spectrum
of
2Cl)+, 467.9= [M-{C=S+O}]+, 408.8=
[ReOCl2(L)] showed peaks which could
[M-{2Cl+(C=S)+O}]+, 354= [M-{O+(N-
be
N-C=S)}]+,
The
FAB(+)
assigned
mass
to
a
spectrum
composition
of
153=
[M-{
O+(N-N-
[ReOCl(L)]+ at m/z= 492 (M-Cl)+. No
C=S)+(H2C=CH2}]+
evidence, however, was found for the
FAB(+) mass spectrum of [Re(L)2]+
molecular ion peak at m/z= 528 (M) +,
showed the following fragments ions
362
detected.
The
National Journal of Chemistry, 2006, Volume 23,352-367
‫المجلد الثالث والعشرون‬-6002-‫المجلة القطرية للكيمياء‬
peak at m/z= 587= [M-(Ph+S)]+, 560=
absence of a resonance assigned to the
[M-(Ph+HN-C=S)]+, 542= [M-(2Ph)]+,
hydrazinic proton which is readily
250= [M-2(Ph+HN-C-NH-N=CH-py)]+.
detectable in the spectrum of the free
NMR Studies
ligand at δ=12.11ppm.
The Re(V), Re(III) and Zn(II) complexes
spectra suggested the presence of the
are diamagnetic (Table 4). The 1H and
[Re(L)2]Cl complex as a single species
13
C NMR spectra of Re(III) complex
in solution. 1H and 13C NMR spectra of
show well defined narrow lines which is
Re(V) complex showed well defined
unusual for what formally d4 octahedral
downfield lines in comparison with that
system and might show the nature of the
for Re(III) and Zn(II) spectra. This can
delocalisation ligand. It was suggested
be attributed to the high oxidation state
that binding of the pyridine nitrogen to
of the metal centre, which is formally d2
form a chelate may account for the
system. The NMR spectra of Re(V)-oxo
diamagnetic nature of the complexes due
complex suggest the presence of two
to the π-system in which the lon pair of
isomers in solution. The signal for the
electrons is donated by pyridine nitrogen
C-S carbon comes at about δ= 193.62
into the t2g set of the metal.[24] Similar
ppm for isomer A and at 184.00 ppm for
mechanisms may be involved in the
isomer B compared with δ= 176.34 ppm
thiosemicarbazone system.
in the free ligand and is consistent with
spectrum
of
Re(III)
The NMR
complex
is
thiolate
consistent with the symmetric nature of
the complex.
The
like
The NMR
coordination
to
rhenium(V) rather than thion.
13
the
The
C NMR of the
deprotonation of the ligand is confirmed
complex is shown in (Figure2) and
in the 1H NMR spectrum of Re(V)-oxo
exhibits 13 resonances. The signal for
complex by the absence of a resonance
the C-S carbon comes around δ= 186.51
assigned to the hydrazinic proton which
ppm compared with δ= 176.34 ppm in
is readily detectable in the spectrum of
the free ligand which is consistent with
the free ligand at δ=12.11ppm.
thiolate type coordination to the rhenium
addition, the
rather than thion.[8] The deprotonation
Re(V)-oxo complex shows resonances at
of the ligand is confirmed in the 1H
chemical shift 10.80 and 10.68 ppm
NMR spectra of Re complex by the
which were assigned to N(4)-H of
363
1
In
H NMR spectrum of
National Journal of Chemistry, 2006, Volume 23,352-367
isomers A and B respectively. These
signals are disappeared on addition
ofD2O to the NMR solution supporting
the presence of two isomers in solution.
There
are
several
possibilities
for
isomers of asymmetric tridentate ligands,
one is the differing in the disposition of
the Re=O group.
superimposable
These are non-
enantiomers,
which
might be observed in solution by NMR
spectroscopy.
isomers
There are also possible
involving
different
conformations of the backbone which
should occur also for Re(III) complex,
but are not apparently observed. This
observation suggests this is not the case.
On the other hand the
13
C spectrum for
Zn(II) (Figure2), shows the signal for
the C-S carbon at δ= 176.49 ppm which
is consistent with thion like coordination
to the zinc. This has been confirmed by
the 1H NMR spectrum of the presence of
the hydrazinic proton at δ=12.11ppm.
364
‫المجلد الثالث والعشرون‬-6002-‫المجلة القطرية للكيمياء‬
National Journal of Chemistry, 2006, Volume 23,352-367
‫المجلد الثالث والعشرون‬-6002-‫المجلة القطرية للكيمياء‬
Table (4) 1H, 13C NMR Data for the ligand and its complexes measured in DMSO-d6 and chemical shift
in ppm ()
Compound
Funct. Group
s (p.p.m) b
-N-N(2)-H a; - N(4)-H a; -N=C-H;
12.11 (1H, s, br.); 10.33 (1H, s); 8.67 (1H, s);
Ar- H; Ar- H Ar- H; Ar- H
8.47(1H, s);8.23 (s, 1H) 8.11 (1H, s); 7.88-7.44(m, 6H)
(C7-S); (C6=N); (C5); (C1); (C8); (C3);
176.32; 153.04; 149.22; 142.97; 138.84; 136.35;
(C10,11); (C9,13); (C2); (C11); (C4).
127.98; 125.87; 124.93; 124.10; 120.52.
- N(4)-H a; -N=C-H ;Ar- H
11.48 (1H, s); 8.48 (1H, s);8.34 (1H, d, JH-H = 7.4 Hz)
Ar- H ;Ar- H
7.88 (2H, d, JH-H = 0.8 Hz) ;7.75 (1H, d, JH-H = 9.76 Hz)
Ar- H; Ar- H; Ar- H ; Ar- H.
7.60 (1H, s); 7.39 (1H, s)7.22-7.15 (1H, m); 6.95 (1H, s)
(C7-S); (C6=N); (C5); (C1); (C8); (C3);
186.51; 159.40; 158.48; 140.78; 136.82; 133.09;
(C10,11); (C9,13); (C2); (C11); (C4).
129.01; 127.99; 126.70; 123.78; 120.08.
- N(4)-H a
10.80 (1H, s)
-N=C-H
9.03 (1H, s)
[HL]
1
H
13
C
[Re(L)2]Cl
1
H
13
C
[ReOCl2(L)]
1
H
Isomer A
Isomer B
13
- N(4)-H
a
10.68 (1H, s)
-N=C-H
8.81 (1H, s)
(C7-S); (C6=N); (CAr); (CAr); (CAr);
193.62; 161.13; 151.06; 141.23; 129.81;
(CAr);(CAr); (CAr); (CAr); (CAr); (CAr).
129.00; 128.70; 128.40; 127.97; 124.82; 121.73.
(C7-S); (C6=N); (CAr); (CAr); (CAr);
184.00; 162.13; 154.91; 150.16; 143.12;
(CAr); (CAr); (CAr);(CAr); (CAr); (CAr).
137.78; 129.28; 126.41; 125.99; 124.82; 123.59.
-N-N(2)-H a;; N(4)-H a; -N=C-H; Ar- H;
Ar- H; Ar- H; Ar- H; Ar- H; Ar- H.
12.11 (1H, s,) ; 10.33 (1H, s); 8.63 (1H, s) 8.45 (1H, s); 8.21
(1H, s); 8.08 (1H, s); 7.58 (1H, s); 7.28 (2H, s); 7.11 (1H, s).
(C7-S); (C6=N); (C5); (C1); (C8); (C3);
(C10,11); (C9,13); (C2); (C11); (C4).
176.49; 151.86; 148.04; 140.97; 139.01; 138.36;
128.19; 125.97; 125.03; 124.65; 121.64.
C
Isomer A
Isomer B
[ZnCl2(HL)]
1
H
13
C
a
disappears on D2O exchange; b chemical shift from TMS.
365
‫المجلد الثالث والعشرون‬-6002-‫المجلة القطرية للكيمياء‬
National Journal of Chemistry, 2006, Volume 23,352-367
Figure 2
13C
NMR spectra of the complexes (DMSO-d6)
+
Cl
H
N
N
Cl
N
N
Re
N
O
S
S
N
Re
S
N
H
N
N
N
N
N
H
The proposed structure of [Re(L)2]+
The proposed structure of [ReOCl2(L)]
Cl
Cl
S
Zn
H
N
N
N
N
H
The proposed structure of [ZnCl2(HL)]
Figure 3 The suggested structure of the complexes
366
National Journal of Chemistry, 2006, Volume 23,352-367
‫المجلد الثالث والعشرون‬-6002-‫المجلة القطرية للكيمياء‬
Chemistry II, vol. 5, Elsevier, 2003,
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18- M. J. Al-Jeboori and Ayed Al-Shihri,
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19- Mohamad J. Al-Jeboori and Abdul
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20- M. Sumar, I. Ivanovic-Burmazovic,
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