Postprint of: Journal of Organometallic Chemistry Volume 696, Issue 3, 1 February 2011, Pages
748–757
Reactivity of TpMe2Ir(C2H4)(DMAD) with carboxylic acids. A DFT study on geometrical
isomers and structural characterization
Verónica Salazar (a), Gloria Sánchez-Cabrera (a), Francisco J. Zuno-Cruz (a), Oscar R. SuárezCastillo (a), Julián Cruz (a), Rosa Padilla (a), Martín Hernández (a), Arián E. Roa (a), Celia
Maya (b), Marco A. Leyva (c), María J. Rosales-Hoz (c), Pandiyan Thangarasu (d)
a Centro de Investigaciones Químicas, Universidad Autónoma del Estado de Hidalgo, Ciudad
Universitaria, Km 4.5 Carretera Pachuca-Tulancingo, 42184 Pachuca, Hidalgo, México
b Instituto de Investigaciones Químicas, Departamento de Química Inorgánica, Consejo
Superior de Investigaciones Científicas (CSIC) and Universidad de Sevilla, Avenida Américo
Vespucio 49, Isla de la Cartuja, 41092 Sevilla, Spain
c Departamento de Química, Centro de Investigación y de Estudios Avanzados del I.P.N.,
Avenida Instituto Politécnico Nacional 2508, Col San Pedro Zacatenco, 07360 México D. F.,
México
d Facultad de Química, Universidad Nacional Autónoma de México (UNAM), Ciudad
Universitaria, Coyoacán, 04510, México D.F., México
Abstract
The thermally unstable adduct TpMe2Ir(C2H4)(DMAD), which was generated “in situ” by the
reaction of DMAD with TpMe2Ir(C2H4)2 (1) at low temperature, reacted with different
carboxylic acids to produce the following compounds: TpMe2Ir(E-C(CO2Me)double bond;
length as m-dashCH(CO2Me))(H2O)(OC(O)C6H4R), (R = H, 2a; o-OH, 2b; o-Cl, 2c; m-Cl, 2d; oNO2, 2e; m-NO2, 2f;o-Me, 2g;p-Me, 2h) and TpMe2Ir(E-C(CO2Me)double bond; length as mdashCH(CO2Me))(H2O)(OC(O)Me) 3. In the reaction of derivative 2a with Lewis bases,
TpMe2Ir(E-C(CO2Me)double bond; length as m-dashCH(CO2Me))(L)(OC(O)C6H5), (L = Py, 4a;
m-Br–Py, 4b; m-Cl–Py, 4c; NCMe, 5) were obtained, of which 4b and 4c were isolated as a
mixture of two isomers in which the substituted pyridine ring was present at different
rotational orientations. All new compounds prepared were characterized by 1H and 13C{1H}
NMR spectroscopy, the structure of compounds 2d, 2h and 4a being determined by X-ray
diffraction analysis. DFT was used to analyze the relative stability and the structural orientation
of the isomers.
Keywords
Alkyne insertion; TpMe2 iridium complexes; Dimethylacetylene dicarboxylate; C–H activation;
DFT calculations
1. Introduction
1
The insertion of unsaturated molecules into M–H or M–C bonds is an important reaction in
organometallic chemistry [1]; in particular, alkynes constitute interesting building blocks in
metal-mediated organic synthesis of compounds that possess many industrial applications [2].
In previous studies, it has been clearly shown that the presence of a Tp′ ligand in a metal
compound (Tp′ stands for any type of hydrotris(pyrazolyl)borate ligand) favors octahedral
coordination [3], [4], [5] and [6], thus, for TpMe2Ir derivatives, the +3 oxidation state is
favorable [7] and [8]. The reaction of the Ir(I) olefin derivative TpMe2Ir(C2H4)2 with
dimethylacetylene dicarboxylate (DMAD) forms the mixed adduct TpMe2Ir(C2H4)(DMAD) at
low temperature and it is stable below 10 °C [9]; above this temperature, in the absence of
other reagents, it evolves by C–H activation of the ethylene, as observed for other related
derivatives of composition TpMe2Ir(C2H4)(L) (L = C2H4, PR3, …) [8], [9] and [10]. This is in
contrast with TpMe2Ir(C2H4)(DMAD), where it forms an iridacyclopentene by the oxidative
coupling of the two unsaturated ligands [11]. The ethylene ligand in the TpMe2Ir derivative is
weakly bonded, and can be easily replaced by other Lewis bases [9].
An early example of the insertion of DMAD into an Ir–H bond reported the formation of an Ealkenyl derivative by the reaction of Ir(H)(CO)(PPh3)3 with DMAD [12]; similarly, the insertion
of this alkyne into M–acyl or M–aryl bonds is also known [13] and [14], as well as for other
insertions, that finally yield alkenyl derivatives [15] and [16]. In this paper, we report the
reaction of the above mentioned Ir(I) derivative TpMe2Ir(C2H4)(DMAD) with aliphatic and
aromatic carboxylic acids to produce the E-alkenyl iridium complexes TpMe2Ir(EC(CO2Me)double bond; length as m-dashCH(CO2Me))(H2O)(OC(O)C6H4R), (R = H, 2a; o-OH,
2b; o -Cl, 2c; m-Cl, 2d; o-NO2, 2e; m-NO2, 2f;o-Me, 2g;p-Me, 2h) and TpMe2Ir(EC(CO2Me)double bond; length as m-dashCH(CO2Me))(H2O)(OC(O)Me) (3) as the result of the
insertion of the alkyne into the hypothetical Ir–H bond formed upon protonation of the metal
compound by the corresponding acid. Furthermore, the adducts TpMe2Ir(E-C(CO2Me)double
bond; length as m-dashCH(CO2Me))(L)(OC(O)C6H5), (L = Py, 4a; m-Br–Py, 4b; m-Cl–Py, 4c;
NCMe, 5) were synthesized by the reaction of the convenient precursor with the appropriate
Lewis base. The existence of two isomers of compounds 4b and 4c was found in solution by
NMR, and DFT calculations were used to analyze their structural orientation.
2. Results and discussion
2.1. Synthesis and characterization of irida-E-alkenyl compounds
In the reaction of TpMe2Ir(C2H4)2 (1) dissolved in CH2Cl2 with DMAD (1.0 equiv amount) and
then with 1.0 equiv amount of a substituted benzoic acid at low temperature (−10 °C), Ealkenyl derivatives 2a–2h were obtained (Scheme 1). These derivatives exhibit a high thermal
stability since they experience no structural transformation when heated in cyclohexane at 150
°C.
The above scheme shows that the two C2H4 molecules in the starting material have been
replaced by alkenyl and carboxylate ligands and the final compounds satisfy the 18 e− count by
the coordination of a molecule of adventitious water. Once the presence of water in the final
products was realized, the reactions were carried out by adding a slight excess of this reagent.
The use of those different carboxylic acids has revealed that there is no significant change in
the chemical reactivity varying the electron-donors OR withdrawing substituent.
The NMR data confirm the structure proposed for compounds 2. For 2a, in the 1H NMR
spectrum, a signal at low field (9.12 ppm) accounts for the coordinated water molecule, while
the alkenyl hydrogen (4-H) resonates at 4.62 ppm. In the 13C{1H} NMR, the carboxylate ester
2
carbons give rise to singlets at 180.8 and 163.4 ppm, while the signal at 181.9 ppm is assigned
to the carboxylate carbon of the former acid. The resonances for two alkenyl carbons are
found at 152.1 (Ir–C(R)) and 126.7 ppm (Ir–C(R)double bond; length as m-dashC(H)(R)).
When the reaction (Scheme 1) was performed with acetic acid instead of a benzoic one, a new
derivative TpMe2Ir(MeCO2Cdouble bond; length as m-dashCHCO2Me)(H2O)(OCOMe) (3,
Scheme 2) was obtained. A deuterium labeled isotopic experimental using D2O and MeCO2D
was performed to show that the source of the proton of the E-alkenyl ligand was from the
acid.
The formation of complexes 2 and 3 can then be proposed as shown in Scheme 3. The known
TpMe2Ir(C2H4)(DMAD) [9] and [17] is initially formed (it is in fact observed in monitoring the
reaction by NMR, CD2Cl2, −40 °C), to be protonated by the acid. Subsequent migratory
insertion of the alkyne into the Ir–H bond, replacement of the ethylene by the corresponding
carboxylate, and coordination of water, would yield the final products.
2.2. Reactivity of the irida-E-alkenyl 2a towards Lewis bases
The reactions of 2a with pyridine (Py) and its monosubstituted derivatives (m-Br–Py, m-Cl–Py)
or with acetonitrile (MeCN) were carried out in order to determine its chemical behavior in the
presence of Lewis bases. These reactions provide the adducts TpMe2Ir(E-C(CO2Me)double
bond; length as m-dashCH(CO2Me))(NC5H4R)(OC(O)C6H5) (R = H, 4a; m-Br, 4b; m-Cl, 4c) and
TpMe2Ir(E-C(CO2Me)double bond; length as m-dashCH(CO2Me))(NCMe)(OC(O)C6H5) (5) in
high yields (≥90%, Scheme 4).
The structure proposed for compounds 4 and 5 is assigned on the bases of NMR and X-ray
analyses (see below). The pyridine derived compound 4a exhibits five different signals for the
pyridine protons in the 1H NMR spectrum, thus indicating a restricted rotation around the Ir–
N(Py) bond. The signal for the alkenyl proton appears at 4.52 ppm, in the same region as the
parent compounds 2. In the reactions of 2a with the halogenated pyridines (m-Br–Py or m-Cl–
Py), compounds 4b and 4c are formed, respectively. The 1H NMR spectra recorded for the
compounds show that there are two different sets of signals (see Experimental section) in each
case, corresponding to two different products, possibly two isomers having different pyridine
ring orientations, due to restricted rotation around the Ir–N.
A variable temperature NMR study (from 25 to 70 °C) shows no exchange between the two
sets of signals in each case. Although we were unable to separate both isomers, 2D-NOESY
NMR spectra indicate for the major isomer in each case, a correlation between the pyridine
14-H (the H atom in the ortho position close to the halide substituent) and the carboxylate 9-H
and H-13 atoms, indicating that the major isomer in both cases is the one with the halide
substituent in the pyridine being close to the carboxylate ligand phenyl ring.
3. DFT geometrical analysis of compound 4b
In order to analyze the pyridine ring orientations in compound 4b, DFT was used to analyze its
structural parameters. First a partial optimization for 4b was performed by DFT; then the
rotational barrier over the equatorial plane (O–Ir–NPy–CPy) was obtained to generate the
different rotamers. In the rotation process, at every 20° change, the geometry was optimized
and the resulting structures are presented in Fig. 1. In the potential energy surface (PES)
analysis, it was found that there are two low energy rotamers that have an energy difference
of 0.5 kcal mol−1. The stable conformer 4b′ (structure IV) (Fig. 1) was found at a rotational
angle of 340°, and another isomer 4b″ (structure II) (Fig. 1) at 160° was detected. In conformer
3
4b′, the bromine atom attached to the pyridine ring is nearest to benzoate group, while for the
other isomer 4b″, the bromine atom is placed on the opposite side of the benzoate group.
Furthermore, other higher energy conformers (structures I at 60° and III at 240°) are shown
(Fig. 1). For the structures II and IV, a full optimization was performed by using different
functionals (LDA, PW91 and PBE) with base sets TZP and the results show that structure IV
(4b′) is more stable than that of II (4b″) having an energy difference about 0.33–0.6 kcal/mol;
this observation is in agreements with the NMR results that the stable isomer is IV (4b′).
The stable conformers [II (4b″) and IV (4b′)] exhibit a distorted octahedral geometry (Fig. 2).
The bond distances obtained for conformer II were: Ir–NTp = 1.97, 2.03 and 2.09 Å and Ir–NPy
= 2.09 Å, and for conformer IV, Ir–NTp = 2.05, 2.06 and 2.13 Å and Ir–NPy = 2.08 Å. In both
structures, the existence of non-conventional hydrogen bonds, i.e., C–H–O = 2.03 Å and C–H–N
= 2.04 Å for II and C–H–O = 2.00 Å and C–H–N = 2.44 Å for IV, is established. The theoretical
geometrical data are in good agreement with that observed in the X-ray structure of
compound 4a.
Since the energy barrier between the stable conformers [II (4b″) and IV (4b′)] is high (13.8 kcal
mol−1), (Fig. 2) the inter-conversion between one isomer and another turns out to be a
difficult process, and there is also a steric hindered congestion between the substituted
pyridine ring and other neighboring groups; as seen in Fig. 3. Therefore; compounds 4b′ and
4b″ are produced separately with different pyridine ring orientations. This observation is in
agreement with the variable temperature NMR results in that no inter-conversion of isomer
4b′ to 4b″ is observed. From the above studies, we propose that the major isomer 4b′ is
assigned to the conformer IV while other isomer 4b″ corresponds to conformer II (Scheme 5).
Similarly, for compounds 4c′ and 4c″, the same calculation method was employed, the results
were almost same as those observed for 4b; this suggests that the existence of the same type
of geometrical rotamers for 4c is manifested. Furthermore, since the non-conventional
hydrogen bonds that are present in the structure can also contribute to the prevention of the
rotation of the pyridine ring, the presence of two conformers in the NMR solution is
confirmed.
4. X-ray diffraction studies
Suitable crystals for compounds 2d, 2h and 4a were obtained and their solid-state structures
were determined by X-ray diffraction analysis.
4.1. Complexes 2d and 2h
ORTEP views of 2d and 2h are shown in Fig. 4 and Fig. 5, respectively while Table 1 shows
selected bond lengths [Å] and angles [°] for compounds 2 and 4a. Both compounds 2 exhibit a
distorted octahedral coordination, as expected for these Ir(III) derivatives [7] and [18]. The
alkenyl bonds C(18)–C(19) have typical values for Cdouble bond; length as m-dashC double
bonds [19] (1.349(7) for 2d and 1.350(8) for 2h). The three distances to iridium Ir(1)–C(18),
Ir(1)–O(6) and Ir(1)–O(1), with values of 2.031(5) 2.089(3) and 2.099(3) Å for 2d and 2.019(6),
2.069(4) and 2.094(4) Å for 2h, fall in the range of a single bond. Because of the higher trans
influence of alkenyl ligand in comparison with the two o-donor ligands water and carboxylate,
the Ir–N(pyrazolyl) bonds trans to the oxygen atoms (2.0225 av 2d and 2h) are shorter than the
distance trans to the carbon atom C(18) (2.148 av 2d and 2h) and 2h[9].
In both structures, the presence of a hydrogen bond between oxygen (benzoic acid) and
hydrogen atoms (water molecule) was observed. The H-bond distance O(7)–H(1B) = 1.811 Å
for 2d and O(7)–H(1A) = 1.712(5) Å for 2h was seen to be smaller than the sum of their Van der
4
Waals radii (ΣVwRO–H = 2.72 Å) [20] and greater than the sum of covalent radii (ΣCRO–H =
0.97 Å) [21].
4.2. Complex 4a
For the case of 4a, two molecules are present in the asymmetric unit cell. Fig. 6 shows an
ORTEP view for one of these molecules. The distortion of the octahedral geometry,
characteristic of TpMe2Ir(III) derivatives, is shown by the deviation of the bond angles: N(2)–
Ir(1)–N(4) = 89.16(18)°, N(2)–Ir(1)–N(6) = 88.30(18)°, N(4)–Ir(1)–N(6) = 87.80(17)°.
Furthermore, the angle for C(18)–Ir(1)–N(7) = 96.1(2)° is greater than that observed for C(18)–
Ir(1)–O(1),91.65(17)° and 90.7(2)° for 2d and 2h, respectively. The shortest angle obtained for
O(6)–Ir(1)–N(7) 83(16)° is due to the bulky ligand (Py vs. H2O) in 4a, implying that the pyridine
ring is arranged in such a way that it interacts with hydrogen atoms of methyl pyrazolyl
fragment (H-4a and H-14c): (H’s(Pz)⋅Py: 3.413 (15) and 3.030(21) Å). Once more, the bond
length of Ir(1)–N(6), of 2.130(4) Å, is larger to the other two distance from Ir to the N atoms of
the pyrazolyl rings, due to the larger trans influence of the alkenyl ligand coordinated trans to
N(6).
The bond distance C(18)–C(19) (1.349(8) Å) observed in 4a is similar to that found in
compounds 2d and 2h, thus indicating that the coordination nature of E-alkenyl fragment is
not affected by coordinating the Lewis base to the metal ion. Furthermore, other bond lengths
Ir(1)–C(18) 2.057(6), Ir(1)–O(6) 2.048(4) and Ir(1)–N(7) 2.068(5) Å are characteristic of single
bonds. It is noticed that the carboxylate carbonyl group is symmetrically located between two
pyrazolyl rings, having a short contact with the CH2Cl2 molecule [H′s(CH2Cl2)⋯O(7): 2.3726(1)
and 2.7037(1) Å].
5. Conclusions
The Ir(1) adduct TpMe2Ir(C2H4)2(DMAD) reacts with a variety of carboxylic acids to yield
alkenyl derivatives of the DMAD ligand, with displacement of the olefin. The products formed,
which contain the alkenyl moiety, the carboxylate ligand and a coordinated molecule of water,
have been shown to react with Lewis bases, this reagent substituting for the labile water. For
the case of two derivatives containing benzoate and m-substituted pyridines, two sets of
isomers are formed, which are derived from restricted rotation of the coordinated Lewis base.
DFT studies were performed to analyze the nature of the mentioned isomers.
6. Experimental section
6.1. General procedures
All experiments were performed under a nitrogen or an argon atmosphere using conventional
Schlenk techniques. Solvents were dried, degassed and then used for the experimental studies.
The prepared compounds were purified by flash column chromatography using silica gel
(Merck 60, 230–400 mesh). Mass spectra were recorded at Mass Service unit, university of
Sevilla, Spain (FAB/High Resolution) and at CINVESTAV-México (HR-LC 1100/MSD TOF Agilent
Technology equipment). Elemental analyses were obtained in a Perkin–Elmer series II Analyzer
2400. Infrared spectra were recorded for the complexes in the solid state as KBr pellets on a
PERKIN Elmer 2000 FT-IR instrument. NMR spectra are measured on JEOL Eclipse 400, Bruker
DRX-500, DRX-400, DPX-300 and VARIAN 400 spectrometers in CDCl3. The 1H or 13C residual
resonance signal of the solvent was used as an internal standard, but chemical shifts are
reported with respect to TMS. Most of the NMR assignments are based on the extensive 1H–
1H decoupling experiments, and homo and heteronuclear two-dimensional spectra. The
5
complexes TpMe2Ir(C2H4)2 (1) and TpMe2Ir(C2H4)(DMAD) were prepared according to
published procedure [8] and [9].
6.2 General procedure for the synthesis of the iridium complexes TpMe2Ir(EC(CO2Me)double bond; length as m-dashCH(CO2Me))(H2O)(OC(O)C6H4R), (R = H, 2a; o-OH,
2b; o-Cl, 2c; m-Cl, 2d; o-NO2, 2e; m-NO2, 2f, o-Me, 2gp–Me, 2h) and TpMe2Ir(EC(CO2Me)double bond; length as m-dashCH(CO2Me))(H2O)(OC(O)Me) (3)
To the compound TpMe2Ir(C2H4)2 (1) dissolved in CH2Cl2 (5 ml), at −10 °C, DMAD (1 equiv)
was added. The respective mixture was stirred for 10 min and then 1.0 equiv amount of
aromatic or aliphatic carboxylic acid was added. The mixture was allowed to reach the room
temperature (25 °C) and then it was stirred for 14 h. The solvent was removed under low
pressure. The product obtained was washed with pentane (10 ml), and dried under vacuum.
6.3. TpMe2Ir(E-C(CO2Me)double bond; length as m-dashCH(CO2Me))(H2O)(OC(O)C6H5) (2a)
The above procedure was employed for the preparation of 2a. The following compounds were
used: TpMe2Ir(C2H4)2 (1) (50 mg; 0.091 mmol), DMAD (11.2 μL; 0.091 mmol), benzoic acid
(11.1 mg; 0.091 mmol) and CH2Cl2 (3.0 mL). Yield: (solid, 62.9 mg, 89%). 1H NMR (CDCl3): δ =
9.12 (br s, 2H, H2O), 7.93 (d, 2H, 3JH–H = 7.7 Hz, 9-H, 13-H), 7.43 (t, 1H, 3JH–H = 7.4 Hz, 11-H),
7.33 (t, 2H, 3JH–H = 7.7 Hz, 10-H, 12-H), 5.86, 5.83, 5.75 (3s, 1H each, 3CHPz), 4.62 (s, 1H, 4-H),
3.72 (s, 3H, 1-CH3), 3.59 (s, 3H, 6-CH3), 2.48, 2.45, 2.40, 2.27, 2.24, 2.19 (6s, 3H each, 6CH3Pz).
13C{1H} NMR (CDCl3): δ = 181.9 (C-7), 180.8 (C-2), 163.4 (C-5), 152.1 (C-3), 152.1, 151.3, 151.2,
144.3, 144.1, 144.0 (6CqPz), 134.1 (C-8), 131.5 (1JC–H = 159.8 Hz, C-11), 129.3 (1JC–H = 161.5
Hz, C-9, C-13), 127.8 (1JC–H = 152.6 Hz, C-10, C-12), 126.7 (1JC–H = 166.1 Hz, C-4), 108.4,
108.2, 107.7, (1JC–H = 174.4 Hz, 3CHPz), 52.1 (1JC–H = 146.8 Hz, CH3-1), 50.9 (1JC–H = 146.1
Hz, CH3-6), 14.6, 13.5, 12.7, 12.3 (in a 1:1:3:1 ratio respectively) (1JC–H = 128.4 Hz, 6CH3Pz). IR
(KBr): ν = 3388 (H2O), 2948 (CH3), 2533 (BH), 1714 (CO) cm−1. HR-MS (ESI-TOF) calcd for MH+
(C28H37BN6O7Ir) 773.2440, MH+ found 773.2458.
6.4. TpMe2Ir(E-C(CO2Me)double bond; length as m-dashCH(CO2Me))(H2O)(OC(O)C6H4o–
OH) (2b)
According to the above mentioned procedure, compound 1 (50 mg; 0.091 mmol), DMAD (11.2
μL; 0.091 mmol), salicylic acid (11.1 mg; 0.091 mmol) and CH2Cl2 (3 mL) were used to prepare
the complex 2b. Yield: (solid, 33.1 mg, 46%). 1H NMR (CDCl3): δ = 11.40 (br s, 1H, OH), 8.40 (br
s, 2H, H2O), 7.69 (dd, 1H, 3JH–H = 7.9, 4JH–H = 1.8 Hz, 13-H), 7.31 (td, 1H, 3JH–H = 7.3, 4JH–H
= 1.8 Hz, 11-H), 6.87 (dd, 1H, 3JH–H = 8.0, 4JH–H = 1.2 Hz, 10-H), 6.73 (td, 1H, 3JH–H = 7.3,
4JH–H = 1.2 Hz, 12-H), 5.87, 5.84, 5.76 (3s, 1H each, 3CHPz), 4.60 (s, 1H, 4-H), 3.75 (s, 3H, 1CH3), 3.58 (s, 3H, 6-CH3), 2.49, 2.45, 2.41, 2.24, 2.16, (6s, 1:1:1:2:1, 3H each, 6CH3Pz). 13C{1H}
NMR (CDCl3): δ = 183.0 (C-7), 181.2 (C-2), 163.5 (C-5), 160.4 (C-9), 152.1, 151.4, 151.3, (3CqPz),
151.1 (C-3), 144.6, 144.5, 144.3 (3CqPz), 134.3 (1JC–H = 158.4 Hz, C-11), 131.3 (1JC–H = 164.4
Hz, C-13), 127.1 (1JC–H = 166.1 Hz, C-4), 118.7 (1JC–H = 162.2 Hz, C-12), 117.1 (1JC–H = 163.7
Hz, C-10), 116.4 (C-8), 108.6, 108.4, 107.9, (1JC–H = 176.1 Hz, 3CHPz), 52.1 (1JC–H = 147.60 Hz,
CH3-1), 51.1 (1JC–H = 146.0 Hz, CH3-6), 14.7, 13.6, 12.8, 12.7, 12.4 (in a 1:1:2:1:1 ratio
respectively) (1JC–H = 128.3 Hz, 6CH3Pz). IR (KBr): ν = 3439 (H2O), 2949 (CH3), 2534 (BH), 1696
(CO) cm−1. HR-MS (ESI-TOF) calcd for MH+ (C28H37BN6O8Ir) 789.2389, found 789.2369.
6.5. TpMe2Ir(E-C(CO2Me)double bond; length as m-dashCH(CO2Me))(H2O)(OC(O)C6H4o–Cl)
(2c)
6
According to the above procedure, compound 2c was obtained by using compound 1 (50 mg;
0.091 mmol), DMAD (11.2 μL; 0.091 mmol), o-chlorobenzoic acid (14.3 mg; 0.091 mmol) and
CH2Cl2 (3.0 mL). Yield: (solid, 36.1 mg, 49.0%). 1H NMR (CDCl3): δ = 8.70 (br, s, 2H, H2O), 7.71
(dd, 1H, 3JH–H = 7.7, 4JH–H = 1.5 Hz, 13-H), 7.24 (dd, 1H, 3JH–H = 8.0, 4JH–H = 1.1 Hz, 10-H),
7.19 (td, 1H, 3JH–H = 7.3, 4JH–H = 1.8 Hz, 11-H), 7.10 (td, 1 H, 3JH–H = 7.40, 4JH–H = 1.1 Hz,
12-H), 5.78, 5.72, 5.67 (3s, 1H each, 3CHPz), 4.53 (s, 1H, 4-H), 3.79 (s, 3H, 1-CH3), 3.52 (s, 3H, 6CH3), 2.37, 2.36, 2.32, 2.27, 2.17, 2.14 (6s, 3H each, 6CH3Pz). 13C{1H} NMR (CDCl3): δ = 179.8
(C-7), 179.7 (C-2), 162.4 (C-5), 151.0, 150.5, 150.3 (3CqPz), 150.3 (C-3), 143.3, 143.1, 143.0
(3CqPz), 133.3 (C-8), 131.3 (C-9), 130.1 (1JC–H = 164.0 Hz, C-13), 129.9 (1JC–H = 162.9 Hz, C11), 129.6 (1JC–H = 166.9 Hz, C-10), 126.1 (1JC–H = 166.1 Hz, C-4), 125.1 (1JC–H = 163.0 Hz, C12), 107.3, 107.1, 106.6 (1JC–H = 175.2 Hz, 3CHPz), 51.5 (1JC–H = 147.6 Hz, CH3-1), 49.9 (1JC–
H = 146.8 Hz, CH3-6), 13.9, 12.4, 12.3, 11.6, 11.3 (in a 1:1:1:2:1 ratio respectively) (1JC–H =
129.2 Hz, 6CH3Pz). IR (KBr): ν = 3426 (H2O), 2925 (CH3), 2532 (BH), 1719 (CO) cm−1. HR-MS
(FAB) calcd for MH+ (C28H35BClN6O7Ir) 807.2056, found 807.2097.
6.6. TpMe2Ir(E-C(CO2Me)double bond; length as m-dashCH(CO2Me))(H2O)(OC(O)C6H4m-Cl)
(2d)
Similarly, compound 1 (50 mg; 0.091 mmol), DMAD (11.2 μL; 0.091 mmol), m-chlorobenzoic
acid (14.4 mg; 0.091 mmol) and CH2Cl2 (3.0 mL) were used to prepare the complex 2d. Yield:
(solid, 50.2 mg, 68%). 1H NMR (CDCl3): δ = 8.83 (br s, 2H, H2O), 7.82 (t, 1H, 4JH–H = 1.7 Hz, 9H), 7.73 (td, 1H, 3JH–H = 8.1, 4JH–H = 1.5 Hz, 13-H), 7.32 (ddd, 1H, 3JH–H = 8.1, 4JH–H = 2.2,
1.1 Hz, 11-H), 7.18 (t, 1H, 3JH–H = 8.1 Hz, 12-H), 5.79, 5.76, 5.67 (3s, 1H each, 3CHpz), 4.53 (s,
1H, 4-H), 3.64 (s, 3H, 1-CH3), 3.51 (s, 3H, 6-CH3), 2.41, 2.37, 2.33, 2.19, 2.15, 2.09 (6s, 3H each,
6CH3pz). 13C{1H} NMR (CDCl3): δ = 179.7 (C-2), 179.3 (C-7), 162.4 (C-5), 150.5 (C-3), 151.0,
150.3, 150.2, 144.3, 143.2, 143.1 (6CqPz), 134.9 (C-8), 132.9 (C-10), 130.5 (1JC–H = 166.10 Hz,
C-11), 128.3 (1JC–H = 167.6 Hz, C-9), 128.1 (1JC–H = 163.0 Hz, C-12), 126.3 (1JC–H = 168 Hz, C13), 125.8 (1JC–H = 165.30 Hz, C-4), 107.4, 107.2, 106.7, (1JC–H = 174.5 Hz, 3CHPz), 51.1 (1JC–
H = 146.8 Hz, CH3-1), 49.8 (1JC–H = 146.0 Hz, CH3-6), 13.6, 12.4, 11.7, 11.3 (in a 1:1:3:1 ratio
respectively) (1JC–H = 129.0 Hz, 6CH3Pz). IR (KBr): ν = 3426 (H2O); 2925 (CH3), 2533 (BH), 1715
(CO) cm−1. HR-MS (FAB) calcd for MH+ (C28H36BClN6O7Ir) 807.2056, found 807.2087.
6.7. TpMe2Ir(E-C(CO2Me)double bond; length as m-dashCH(CO2Me))(H2O)(OC(O)C6H4o–
NO2) (2e)
For complex 2e, compound 1 (50 mg; 0.091 mmol), DMAD (11.2 μL; 0.091 mmol), onitrobenzoic acid (15.3 mg; 0.091 mmol) and CH2Cl2 (3 mL) were employed. Yield: (solid, 66.0
mg, 88.2%). 1H NMR (CDCl3): δ = 8.42 (br, s, 2H, H2O), 7.93, 7.50 (m, 4-H, 10-H–13-H), 5.88,
5.82, 5.74 (3s, 1H each, CHPz), 4.57 (s, 1H, 4-H), 3.80 (s, 3H, 1-CH3), 3.59 (s, 3H, 6-CH3), 2.46,
2.44, 2.40, 2.32, 2.20, 2.19 (6s, 3H each, 6CH3Pz). 13C{1H} NMR (CDCl3): δ = 180.8 (C-2), 177.9
(C-7), 163.6 (C-5), 152.2, 152.0, 151.4 (3CqPz), 151.0 (C-3), 150.3 (C-9), 144.6, 144.4, 144.3
(3CqPz), 131.5, 131.2, 131.0, 123.0 (1JC–H = 166.0 Hz, C-10–C-13), 128.7 (C-8), 127.5 (1JC–H =
166.0 Hz, C-4), 108.6, 108.3, 107.9 (1JC–H = 176.1 Hz, 3CHPz), 52.7 (1JC–H = 146.3), 51.2 (1JC–
H = 147.6 Hz, CH3-6), 15.0, 13.6, 13.2, 13.0, 12.9, 12.6 (1JC–H = 128.4 Hz, 6CH3Pz). IR (KBr): ν =
3427 (H2O), 2925 (CH3), 2534 (BH), 1714 (CO) cm−1. HR-MS (ESI-TOF) calcd for MH+
(C28H36BN7O9Ir) 818.2291, found 818.2290.
6.8. TpMe2Ir(E-C(CO2Me)double bond; length as m-dashCH(CO2Me))(H2O)(OC(O)C6H4mNO2) (2f)
7
In the same procedure mentioned above, compound 1 (50 mg; 0.091 mmol), DMAD (11.2 μL;
0.091 mmol), m-nitrobenzoic acid (15.2 mg; 0.091 mmol) and CH2Cl2 (3 mL) were used to
prepare complex 2f. Yield: (solid, 56.1 mg, 75.0%). 1H NMR (CDCl3): δ = 8.76 (t, 1H, 4JH–H =
1.9 Hz, 9-H), 8.73 (br, s, 2H, H2O), 8.30 (ddd, 1H, 3JH–H = 8.0, 4JH–H = 2.2, 1.1 Hz, 11-H), 8.27
(dd, 1H, 3JH–H = 8.1, 4JH–H = 1.5 Hz, 13-H), 7.54 (t, 1 H, 3JH–H = 8.1 Hz, 12-H), 5.90, 5.86, 5.77
(3s, 1H each, 3CHpz), 4.62 (s, 1H, 4-H), 3.70 (s, 3H, 1-CH3), 3.58 (s, 3H, 6-CH3), 2.50, 2.46, 2.42,
2.30, 2.24, 2.17 (6s, 3H each, 6CH3Pz). 13C{1H} NMR (CDCl3): δ = 180.8 (C-2), 179.2 (C-7),
163.6 (C-5), 152.2, 151.5, 151.3 (3CqPz), 151.3 (C-3), 148.3 (C-10), 144.7, 144.6, 144.5 (3CqPz),
136.1 (C-8), 135.0 (1JC–H = 165.2 Hz, C-13), 129.2 (1JC–H = 165.2 Hz, C-12), 127.2 (1JC–H =
166.3 Hz, C-4), 126.3 (1JC–H = 177.1 Hz, C-11), 124.6 (1JC–H = 170.6 Hz, C-9), 108.7, 108.6,
108.0 (1JC–H = 175.20 Hz, 3CHPz), 52.4 (1JC–H = 146.8 Hz, CH3-1), 51.2 (CH3-6), 14.8, 13.7,
13.0, 12.9, 12.5 (in a 1:1:1.2:1 ratio respectively) (1JC–H = 129.2 Hz, 6CH3Pz). IR (KBr): ν = 3420
(H2O), 2926 (CH3), 2531 (BH), 1715 (CO) cm−1. HR-MS (ESI-TOF) calcd for MH+
(C28H36BN7O9Ir) 818.2291, found 818.2291.
6.9. TpMe2Ir(E-C(CO2Me)double bond; length as m-dashCH(CO2Me))(H2O)(OC(O)C6H4o–
CH3) (2g)
With the same general procedure, the complex 2g was prepared by using compound 1 (50 mg;
0.091 mmol), DMAD (11.2 μL; 0.091 mmol), o-methylbenzoic acid (22.0 mg; 0.091 mmol) and
CH2Cl2 (3.0 mL). Yield: (solid, 70.0 mg, 97%). 1H NMR (CDCl3): δ = 9.13 (br, s, 2H, H2O); 7.82
(d, 1H, 3JH–H = 7.4 Hz, 13-H); 7.29 (t, 1H, 3JH–H = 7.3 Hz, 12-H); 7.13 (d, H, 3JH–H = 7.3 Hz, 10H), 7.12 (t, 1H, 3JH–H = 7.3 Hz, 11-H); 5.84, 5.80, 5.75 (3s, 1H each, 3CHPz); 4.60 (s, 1H, 4-H);
3.83 (s, 3H, 1-CH3); 3.59 (s, 3H, 6-CH3); 2.49 (s, 3H, CH3o–CH3); 2.44, 2.41, 2.25, 2.23, 2.21 (5s,
in a 6:3:3:3:3 H ratio respectively, 6CH3Pz). 13C{1H} NMR (CDCl3): δ = 183.6 (C-7); 180.7 (C-2);
163.4 (C-5); 152.0 (C-3); 151.8, 151.2, 150.4, 144.2, 144.0, 143.9 (6CqPz); 138.6 (C-8); 133.8 (C9); 131.2 (1JC–H = 158.4 Hz, C-10); 130.5 (1JC–H = 160.3 Hz, C-13); 125.2 (1JC–H = 163.8 Hz, C11,C-12); 126.8 (1JC–H = 166.2 Hz, C-4); 108.3, 108.0, 107.6 (1JC–H = 171.0 Hz, 3CHPz); 52.2
(1JC–H = 146.9 Hz, CH3-1); 50.9 (1JC–H = 146.2 Hz, CH3-6); 21.4 (1JC–H = 127.7 Hz, CH3o–
CH3); 14.7, 13.5, 13.0, 12.6, 12.4 (in a 1:1:1:2:1 ratio respectively) (1JC–H = 130.0 Hz, 6CH3Pz).
IR (KBr): ν = 3439 (H2O), 2922 (CH3), 2533 (BH), 1692 (CO) cm−1. HR-MS (ESI-TOF) calcd for
MH+ (C29H39BN6O7Ir) 787.2597, found.787.2600.
6.10. TpMe2Ir(E-C(CO2Me)double bond; length as m-dashCH(CO2Me))(H2O)(OC(O)C6H4p–
CH3) (2h)
Compound 1 (50 mg; 0.091 mmol), DMAD (11.2 μL; 0.091 mmol), p-methylbenzoic acid (22.0
mg; 0.091 mmol) and CH2Cl2 (3.0 mL) were used to prepared complex 2h by employing the
above described general method. Yield: (solid, 65.0 mg, 90.3%). 1H NMR (CDCl3): δ = 9.17 (br,
s, 2H, H2O); 7.81(d, 2H, 3JH–H = 8.4 Hz, 9-H, 13-H); 7.13 (d, 2H, 3JH–H = 8.4 Hz, 10-H, 12-H);
5.85, 5.82, 5.74 (3s, 1H each, 3CHPz); 4.60 (s, 1H, 4-H); 3.71 (s, 3H, 1-CH3); 3.58 (s, 3H, 6-CH3);
2.35 (s, 3H, 14-CH3); 2.47, 2.44, 2.40, 2.25, 2.23, 2.17 (6s, 3H each, 6CH3Pz). 13C{1H} NMR
(CDCl3): δ = 182.3 (C-7); 181.0 (C-2); 163.7 (C-5); 152.6 (C-3); 152.3, 151.5, 144.4, 144.3, 144.2
(in a 1:2:1:1:1 ratio respectively) (6CqPz); 142.1 (C-11); 131.6 (C-8); 129.5 (1JC–H = 161.4 Hz, C9, C-13); 128.7 (1JC–H = 158.4 Hz, C-10, C-12); 126.7 (1JC–H = 166.1 Hz, C-4); 108.5, 108.4,
107.9 (1JC–H = 175.3 Hz, 3CHPz); 52.4 (1JC–H = 146.1 Hz, CH3-1); 51.1 (1JC–H = 146.1 Hz, CH36); 21.7 (1JC–H = 126.0 Hz, CH3p–CH3); 14.7, 13.7, 13.0, 12.9, 12.8, 12.5 (1JC–H = 129.1 Hz,
6CH3Pz). IR (KBr): ν = 3407 (H2O), 2950 (CH3), 2533 (BH), 1698 (CO) cm−1. HR-MS (ESI-TOF)
calcd for MH+ (C29H39BN6O7Ir) 787.2597, found 787.2597.
6.11. TpMe2Ir(E-C(CO2Me)double bond; length as m-dashCH(CO2Me))(H2O)(OC(O)Me) (3a)
8
Similarly, the product was obtained with using compound 1 (50 mg; 0.091 mmol), DMAD (11.2
μL; 0.091 mmol), acetic acid (5.24 μL; 0.091 mmol) and CH2Cl2 (3.0 mL). Yield: 49.6 mg, 76.3%
of beige solid. 1H NMR (CDCl3): δ = 8.78 (br, s, 2H, H2O), 5.87, 5.80, 5.73 (3s, 1H each, 3CHPz),
4.58 (s, 1H, 4-H), 3.93 (s, 3H, 1-CH3), 3.60 (s, 3H, 6-CH3), 1.99 (s, 3H, 8-CH3), 2.43, 2.42, 2.38,
2.25, 2.22, 2.18 (6s, 3H each, 6CH3Pz). 13C{1H} NMR (CDCl3): δ = 187.7 (C-7), 180.7 (C-2),
163.7 (C-5), 152.4, 152.2, 151.3 (3CqPz), 151.3 (C-3), 144.4, 144.3, 144.26 (3CqPz), 126.9 (1JC–
H = 166.1 Hz, C-4), 108.6, 108.4, 107.9 (1JC–H = 175.3 Hz, 3CHPz), 52.3 (1JC–H = 146.9 Hz, CH31), 51.1 (1JC–H = 146.0 Hz, CH3-6), 24.2 (1JC–H = 127.6 Hz, CH3-8), 14.4, 12.9, 12.8, 12.78, 12.5
(in a 1:1:2:1:1 ratio respectively) (1JC–H = 124,6 Hz, 6CH3Pz). IR (KBr): ν = 3419 (H2O), 2926
(CH3), 2529 (BH), 1713 (CO) cm−1. HR-MS (ESI-TOF) calcd for MH+ (C23H35BN6O7Ir) 711.2284,
found 711.2286.
6.12. TpMe2Ir(E-C(CO2Me)double bond; length as m-dashCH(CO2Me))(NC6H5)(OC(O)C6H5)
(4a)
The solution of compound 2a (50 mg; 0.065 mmol) dissolved in pyridine (1.0 mL; 12.4 mmol)
was stirred at 60 °C for 12 h. The volatiles were removed in vacuum, and the quantitative
conversion into 4a was verified by 1H NMR spectroscopy. The obtained compound was
crystallized from hexane at −20 °C, Yield: (solid, 48.0 mg, 89%). 1H NMR (CDCl3): δ = 9.20 (d,
1H, 3JH–H = 5.5 Hz, 14-H), 8.02 (d, 2H, 3JH–H = 7.7 Hz, 9-H, 13-H), 7.65 (t, 1H, 3JH–H = 7.3 Hz,
16-H), 7.50 (d, 1H, 3JH–H = 5.4 Hz, 18-H), 7.36 (t, 1H, 3JH–H = 6.2 Hz, 17-H), 7.27 (m, 3H, 10-H–
12-H), 6.91 (t, 1H, 3JH–H = 6.6 Hz, 15-H), 5.76, 5.63, 5.56 (3s, 1H each, CHPz), 4.52 (s, 1H, 4-H),
3.88 (s, 3H, 1-CH3), 3.46 (s, 3H, 6-CH3), 2.44, 2.38, 2.36, 1.93, 1.54, 0.83 (6s, 3H each, 6CH3Pz).
13C{1H} NMR (CDCl3): δ = 177.9 (C-2), 171.7 (C-7), 164.0 (C-5), 155.8 (C-3), 154.0 (1JC–H =
178.4 Hz, C-18), 153.5 (1JC–H = 182.20 Hz, C-14), 152.7, 151.2, 151.1, 144.6, 143.2 (in a
1:1:1:1:2 ratio respectively) (6CqPz), 137.7 (1JC–H = 159.1 Hz, C-16), 135.8 (C-8), 130.0 (1JC–H
= 159.1 Hz, C-10), 129.7 (1JC–H = 162.20 Hz, C-9, C-13), 127.6 (1JC–H = 158.4 Hz, C-11,C-12),
127.2 (1JC–H = 166.3 Hz, C-4), 124.5 (1JC–H = 166.8 Hz, C-15), 123.9 (1JC–H = 169.9 Hz, C-17),
108.3, 107.5, 107.2 (1JC–H = 173.8 Hz, 3CHPz), 51.0 (1JC–H = 146.1 Hz, CH3-6), 50.9 (1JC–H =
146.1 Hz, CH3-1), 15.3, 14.7, 13.0, 12.7, 10.9 (in a 1:1:2:1:1 ratio respectively) (1JC–H = 128.4
Hz, 6CH3Pz). IR (KBr): ν = 3447 (H2O), 2927 (CH3), 2532 (BH), 1703 (CO) cm−1. The compound
shows decomposition during mass spectrometric experiments.
6.13. TpMe2Ir(E-C(CO2Me)double
Br)(OC(O)C6H5) (4b)
bond;
length
as
m-dashCH(CO2Me))(NC5H4m-
A solution of compound 2a (25 mg; 0.033 mmol) in CH2Cl2 (3.0 mL) and m-Br–pyridine (10.0
μl; 0.098 mmol) was stirred at 60 °C for 5 h. After the reaction was completed, volatiles were
removed in vacuum and the quantitative conversion into 4b was verified by 1H NMR
spectroscopy. 4b′:4b″ in a 80:20 ratio. Major isomer 4b′: 1H NMR (CDCl3): δ = 9.47 (d, 1H, 4JH–
H = 2.0 Hz, 14-H), 9.29 (d, 1H, 3JH–H = 5.6 Hz, 18-H), 8.10 (m, 2H, 9-H, 13-H), 7.88 (dm, 1H,
3JH–H = 8.4 Hz, 16-H), 7.57 (d, 1H, 3JH–H = 5.6 Hz, 11-H), 7.35 (m, 2H, 10-H, 12-H), 6.88 (dd,
1H, 3JH–H = 8.0, 5.6 Hz, 17-H), 5.83, 5.72, 5.63 (3s, 1H each, CHPz), 4.57 (s, 1H, 4-H), 4.06 (s,
3H, 1-CH3), 3.54 (s, 3H, 6-CH3), 2.51, 2.45, 2.42, 2.00, 1.63, 0.95 (6s, 3H each, 6CH3Pz).
13C{1H} NMR (CDCl3): δ = 177.2 (C-2), 171.2 (C-7), 163.7 (C-5), 154.8 (C-3), 154.7 (1JC–H =
193.9 Hz, C-14), 152.0 (1JC–H = 162.0 Hz, C-18), 152.5, 150.7, 150.6, 144.4, 143.1, 143.0
(6CqPz), 140.0 (1JC–H = 171.0 Hz, C-16), 135.1 (C-8), 129.9 (1JC–H = 158.1 Hz, C-11), 129.3
(1JC–H = 160.9 Hz, C-9, C-13), 127.4 (1JC–H = 158.7 Hz, C-10, C-12), 126.9 (1JC–H = 165.7 Hz, C4), 124.7 (1JC–H = 169.0 Hz, C-17), 119.1 (C-15), 108.1, 107.3, 107.1 (1JC–H = 174.7 Hz, 3CHPz),
51.1 (1JC–H = 145.5 Hz, CH3-6), 50.7 (1JC–H = 145.3 Hz, CH3-1), 15.0, 14.5, 12.7, 12.4, 10.7 (in
a 1:1:2:1:1 ratio respectively) (1JC–H = 128.7 Hz, 6CH3Pz). Minor isomer 4b″: 1H NMR (CDCl3):
9
δ = 8.68 (s, 1H, 4JH–H = 1.6 Hz, 14-H), 8.53 (d, 1H, 3JH–H = 3.6 Hz, 18-H), 8.09 (m, 2H, 9-H, 13H), 7.82 (dm, 1H, 3JH–H = 8.4 Hz, 16-H), 7.35 (m, 3H, 11-H, 12-H), 7.20 (dd, 1H, 3JH–H = 8.0, 4.8
Hz, 17-H), 5.87, 5.70, 5.66 (3s, 1H each, CHPz), 4.56 (s, 1H, 4-H), 3.95 (s, 3H, 1-CH3), 3.54 (s, 3H,
6-CH3), 2.53, 2.45, 1.99, 1.65, 0.98 (5s, in a 3:6:3:3:3 H ratio respectively, 6CH3Pz). 13C{1H}
NMR (CDCl3): δ = 177.5 (C-2), 171.3 (C-7), 163.7 (C-5), 154.7 (C-3), 154.3 (1JC–H = 190.0 Hz, C14), 151.8 (1JC–H = 164.5 Hz, C-18), 152.4, 150.5, 150.6, 144.7, 143.2, 143.0 (6CqPz), 140.2
(1JC–H = 170.9 Hz, C-16), 135.4 (C-8), 128.1 (1JC–H = 160.4 Hz, C-11), 129.3 (1JC–H = 160.9 Hz,
C-9, C-13), 126.9 (1JC–H = 165.0 Hz, C-10, C-12), 127.0 (1JC–H = 165.6 Hz, C-4), 124.2 (1JC–H =
168.5 Hz, C-17), 119.4 (C-15), 108.2, 107.3, 107.2 (1JC–H = 173.4 Hz, 3CHPz), 50.8 (1JC–H =
145.4 Hz, CH3-6), 50.7 (1JC–H = 145.3 Hz, CH3-1), 14.8, 14.4, 12.8, 12.7, 12.5, 10.9 (1JC–H =
128.4 Hz, 6CH3Pz). Anal. for C33H38N7BO6BrIr·0.1CH2Cl2 (Mw = 920.13448): calcd: C, 43.21;
H, 4.18; N, 10.66 Expt.: C, 42.33; H, 4.16; N, 9.89.
6.14. TpMe2Ir(E-C(CO2Me)double
Cl)(OC(O)C6H5) (4c)
bond;
length
as
m-dashCH(CO2Me))(NC5H4m-
A solution of compound 2a (25 mg, 0.033 mmol) in CH2Cl2 (3.0 mL) and m-Cl–pyridine (9 μl,
0.096 mmol) was stirred at 60 °C for 5.0 h and then volatiles were removed under reduced
pressure. The quantitative conversion into 6c was confirmed by 1H NMR spectroscopy. 4c′:4c″
in a 76:24 ratio. Major Isomer 4c′: 1H NMR (CDCl3): δ = 9.36 (d, 1H, 4JH–H = 2.4 Hz, 14-H), 9.25
(d, 1H, 3JH–H = 5.6 Hz, 18-H), 8.12 (m, 2H, 9-H, 13-H), 7.75 (dm, 1H, 3JH–H = 8.8 Hz, 16-H),
7.54 (d, 1H, 3JH–H = 6.0 Hz, 11-H), 7.41 (dd, 1H, 3JH–H = 13.6, 8.0 Hz, 10-H), 7.37 (m, 1H, 12H), 6.94 (dd, 1H, 3JH–H = 8.4, 6.0, 17-H), 5.84, 5.73, 5.64 (3s, 1H each, CHPz), 4.59 (s, 1H, 4-H),
4.05 (s, 3H, 1-CH3), 3.55 (s, 3H, 6-CH3), 2.52, 2.46, 2.44, 2.02, 1.63, 0.96 (6s, 3H each, 6CH3Pz).
13C{1H} NMR (CDCl3): δ = 174.6 (C-2), 168.8 (C-7), 161.5 (C-5), 152.8 (C-3), 150.7 (1JC–H =
186.6 Hz, C-14), 149.7 (1JC–H = 184.0 Hz, C-18), 150.5, 148.8, 148.7, 142.7, 141.4, 141.3
(6CqPz), 135.7 (1JC–H = 166.3 Hz, C-16), 133.6 (C-8), 129.9 (C-15), 128.5 (1JC–H = 154.4 Hz, C11), 127.9 (1JC–H = 156.9 Hz, C-9, C-13), 126.1 (1JC–H = 155.4 Hz, C-10, C-12), 125.6 (1JC–H =
160.7 Hz, C-4), 123.2 (1JC–H = 164.3 Hz, C-17), 107.2, 106.5, 106.3 (1JC–H = 173.4 Hz, 3CHPz),
51.6 (1JC–H = 146.4 Hz, CH3-6), 51.3 (1JC–H = 145.9 Hz, CH3-1), 16.5, 16.1, 14.4, 14.0, 12.4 (in
a 1:1:2:1:1 ratio respectively) (1JC–H = 128.3 Hz, 6CH3Pz). Minor isomer 4c″: 1H NMR (CDCl3):
δ = 8.58 (d, 1H, 4JH–H = 2.0 Hz, 14-H), 8.49 (dd, 1H, 3JH–H = 4.8, 4JH–H = 1.2 Hz, 18-H), 8.10
(m, 2H, 9-H, 13-H), 7.67 (dm, 1H, 3JH–H = 8.4 Hz, 16-H), 7.37 (m, 3H, 10-H, 11-H, 12-H), 7.27
(dd, 1H, 3JH–H = 13.2, 5.6 Hz, 17-H), 5.88, 5.71, 5.67 (3s, 1H each, CHPz), 4.58 (s, 1H, 4-H), 3.96
(s, 3H, 1-CH3), 3.55 (s, 3H, 6-CH3), 2.54, 2.46, 2.01, 1.66, 0.99 (5s, in a 3:6:3:3:3 H, 6CH3Pz).
13C{1H} NMR (CDCl3): δ = 174.9 (C-2), 168.9 (C-7), 161.5 (C-5), 152.8 (C-3), 150.5 (1JC–H =
183.2.0 Hz, C-14), 149.5 (1JC–H = 184.0 Hz, C-18), 150.3, 148.8, 148.6, 142.9, 141.5, 141.3
(6CqPz), 135.8 (1JC–H = 166.2 Hz, C-16), 133.9 (C-8), 130.3 (C-15), 126.7 (1JC–H = 156.1 Hz, C11), 127.9 (1JC–H = 156.9 Hz, C-9, C-13), 125.1 (1JC–H = 155.4 Hz, C-10, C-12), 125.7 (1JC–H =
160.7 Hz, C-4), 122.7 (1JC–H = 164.2 Hz, C-17), 107.4, 106.5, 106.4 (1JC–H = 174.8 Hz, 3CHPz),
51.4 (1JC–H = 146.3 Hz, CH3-6), 51.3 (1JC–H = 145.9 Hz, CH3-1), 16.4, 16.0, 14.5, 14.1, 12.6 (in
a 1:1:2:1:1 ratio respectively) (1JC–H = 127.2 Hz, 6CH3Pz). Anal. for
C33H38N7BO6ClIr·0.5CH2Cl2 (Mw = 909.6566): calcd: C, 44.23; H, 4.32; N, 10.78 Expt.: C,
44.09; H, 4.28; N, 9.94.
6.15 TpMe2Ir(E-C(CO2Me)double bond; length as m-dashCH(CO2Me))(OC(O)C6H5)(NCMe)
(5)
A solution of compound 2a (50 mg, 0.065 mmol) in acetonitrile (3.0 mL, 54 mmol) was stirred
at 60 °C for 12 h. After the reaction was completed, volatiles were removed in vacuum. The
quantitative conversion into 5 was established by 1H NMR spectroscopy. The compound
10
obtained was crystallized from hexane at −20 °C, Yield (solid, 50.5 mg, 98%). 1H NMR (CDCl3):
δ = 7.87 (d, 2H, 3JH–H = 7.30 Hz, 9-H, 13-H); 7.33 (t, 1H, 3JH–H = 7.40 Hz, 11-H); 7.26 (t, 2H,
3JH–H = 6.60 Hz, 10-H, 12-H); 5.82, 5.80, 5.78 (3s, 1H each, 3CHPz); 4.64 (s, 1H, 4-H); 3.80 (s,
3H, 1-CH3); 3.57 (s, 3H, 6-CH3); 2.74 (s, 3H, 14-CH3); 2.44, 2.41, 2.29, 2.20, 2.12 (5s, in a
6:3:3:3:3 H ratio respectively, 6CH3Pz).13C{1H} NMR (CDCl3): δ = 177.8 (C-2); 173.2 (C-7);
163.7 (C-5); 152.3 (C-3); 152.0, 151.7, 151.0, 144.2, 143.8, 143.5 (6CqPz); 135.6 (C-8); 129.8 (C11); 129.3 (C-9, C-13); 127.3 (C-10, C-12); 125.8 (C-4); 117.7 (C-15); 108.0, 106.9 (in a 2:1 ratio
respectively) (3CHPz); 51.7 (CH3-1); 50.8 (CH3-6); 14.8, 14.5, 12.9, 12.8, 12.7, 12.3 (6CH3Pz);
3.8 (CH3-14). IR (KBr): ν = 2924 (CH3); 2519 (BH); 2237 (CN); 1710 (CO) cm−1. HR-MS (ESI-TOF)
calcd for MH+ (C30H38BN7O6Ir) 796.2600, found 796.2604.
7. Computational procedure
Calculations were carried out by using Amsterdam Density Functional (ADF) code [22]. The
geometry optimization was worked out using the LDA [23], PW91 [24] and PBE [25] exchangecorrelation (XC) functional. The triple ζ + polarization (TZP) basis of Slater-type orbitals
provided with the ADF package was used for all atoms. Full optimization geometry was
performed for compound 4b using the X-ray structure data of compound 4a and then a
rotational barrier analysis for the optimized geometry by rotating the pyridine ring in the
counterclockwise up to 360° through a step 20° around the Ir–N bond and the dihedral angle
(O–Ir–NPy–CPy) was used as starting point to generate the rotamers; in each step, all
structures being fully optimized and they were checked by vibrational frequency analysis.
8. X-ray structure determination
Details for data collection structure refinement for 2d, 2h and 4a are presented in Table 2. The
crystals (2d, and 4a) were mounted on glass fibers and the crystal 2h was mounted in
MicroMounts (MitGen company, www.mitegen.com). For 2h (as solvated 2h·C5H12), data
were collected using a Enraf–Nonius Kappa CCD Reflections and data for 2d (as solvated
2d·C5H12) and 4a (as solvated 4a·CH2Cl2) were collected on a Bruker SMART 5000 CCD-based
diffractometer. For all compounds, all non-hydrogen atoms were refined anisotropically.
Hydrogen atoms were fixed at idealized refined positions. Data collection and the
determination of cell dimensions for all compounds were carried out using the collect software
[26] and HKL Scalepack [27] The frames were integrated with the SAINT software package [28]
using a narrow-frame algorithm. A semi-empirical absorption correction method (SADABS) [29]
was applied in all cases. All structures were resolved by direct methods, completed by
subsequent difference Fourier synthesis, and refined by full-matrix least-squares procedures
using the SHELX-97 package [29].
Acknowledgments
Authors acknowledge the projects Consejo Nacional de Ciencia y Tecnología (CONACYT,
Mexico, Grant No.: 025424, J110.380, I32816 and 84453), “Ricardo J. Zevada” Foundation, and
the bilateral assistance CSIC (Sevilla, Spain)-CONACYT-UAEH (México) for the financial support.
Additionally, Universidad Autónoma del Estado de Hidalgo (UAEH) Project No. DIP-ICBI-AAQ056 is gratefully acknowledged. J. Cruz appreciates to Programa de Mejoramiento del
Profesorado (PROMEP)-UAEH for the additional financial support (Grant No 103.5/08/5390).
RMP, MH and AE thank CONACYT for their scholarships.
11
References
[1] D. Austruc
Organometallic Chemistry and Catalysis
Springer-Verlag, Berlin Heidelberg New York (2007) (Chapter 6). pp. 140–142
[2] Ch. S. Chin, G. Won, D. Chong, M. Kim, H. Lee
Acc. Chem. Res., 35 (2002), p. 218
[3] S. Trofimenko
Scorpionates-The Coordination Chemistry of Polypyrazolylborate Ligands
Imperial College Press, London (1999) p. 282
[4] S. Trofimenko
Chem. Rev., 93 (1993), p. 943
[5] G. Parkin
Adv. Inorg. Chem., 42 (1995), p. 291
[6] P.K. Byers, A.J. Canty, R.T. Honeyman
Adv. Organomet. Chem., 34 (1992), p. 1
[7] C. Slugovc, I. Padilla-Martinez, S. Sirol, E. Carmona
Coord. Chem. Rev., 213 (2001), p. 129
[8] Y. Alvarado, O. Boutry, E. Gutierrez, A. Monge, M.C. Nicasio, M.L. Poveda, P.J. Pérez, C.
Ruiz, C. Bianchini, E. Carmona
Chem. Eur. J., 3 (1997), p. 860
[9] M. Paneque, C.M. Posadas, M.L. Poveda, Nuria Rendón, K. Mereiter
Organometallics, 26 (2007), p. 3120
[10] E. Gutiérrez-Puebla, A. Monge, M.C. Nicasio, P.J. Pérez, M.L. Poveda, L. Rey, C. Ruíz, E.
Carmona
Inorg. Chem., 37 (1998), p. 4538
[11] J.M. O′Connor, A. Closson, P. Gantzel
J. Am. Chem. Soc., 124 (2002), p. 2434
[12] W.H. Baddley, M.A. Fraser
J. Am. Chem. Soc., 91 (1969), p. 3661
[13] K.R. Reddy, K. Surekha, G.-H. Lee, S.-M. Peng, S.-T. Liu
Organometallics, 20 (2001), p. 5557
12
[14] T. Yagyu, K. Osakada, M. Brookhart
Organometallics, 19 (2000), p. 2125
[15] E. Hevia, J. Pérez, L. Riera, V. Riera, D. Miguel
Organometallics, 21 (2002), p. 1750
[16] L. Cuesta, E. Hevia, D. Morales, J. Pérez, V. Riera, M. Seitz, D. Miguel
Organometallics, 24 (2005), p. 1772
[17] M. Paneque, C.M. Posadas, M.L. Poveda, N. Rendón, E. Alvarez, K. Mereiter
Chem. Eur. J., 13 (2007), p. 5160
[18] D.M. Tellers, S.J. Skoog, R.G. Bergman, T.B. Gunnoe, W.D. Harman
Organometallics, 19 (2000), p. 2428
[19] M. Paneque, M.L. Poveda, V. Salazar, E. Gutierrez-Puebla, A. Monge
Organometallics, 19 (2000), p. 3120
[20] A. Bondi
J. Phys. Chem., 68 (1964), p. 441
[21] B. Cordero, V. Gómez, A.E. Platero-Prats, M. Revés, J. Echeverría, E. Cremades, F.
Barragán, S. Alvarez
Dalton Trans. (2008), p. 2832
[22] ADF: Amsterdam density functional, scientific computing and modelling (SCM),
Theoretical Chemistry, Vrije Universiteit, Amsterdam. The Netherlands.
[23] S.H. Vosko, L. Wilk, M. Nusair
Can. J. Phys., 58 (1980), p. 1200
[24] J.P. Perdew, J.A. Chevary, S.H. Vosko, K.A. Jackson, M.R. Pederson, D.J. Sing, C. Fiolhais
Phys. Rev. B., 46 (1992), p. 6671
[25] J.P. Perdew, K. Burke, M. Ernzerhof
Phys. Rev. Lett., 77 (1996), p. 3865
[26] Nonius
COLLECT
Nonius BV, Delft, The Netherlands (2001)
[27] Z. Otwinowski, W. Minor
Methods in Enzymology
Academic Press, New York (1997) p. 307
13
[28] Bruker programs: SMART. Version 5.629. SAINT+.
[29] G.M. Sheldrick
Acta. Crystallogr., A64 (2008), p. 112
Figure captions
Figure 1. Energetic profile of rotamers I–IV.
Figure 2. Structures of the two most stable conformers II and IV.
Figure 3. Space filling diagram of the two most stable conformers IV (4b′) and II (4b″).
Figure 4. ORTEP view of compound 2d (30% probability, H atoms except for water are omitted
for clarity).
Figure 5. ORTEP view of compound 2h (30% probability level, H atoms except for water are
omitted for clarity).
14
Table 1. Selected bond lengths [Å] and angles [°] for compounds 2d, 2h and 4a.
2d
2h
4a
Bond lengths
Ir(1)–N(6)
Ir(1)–N(2)
Ir(1)–N(4)
Ir(1)–O(1)
Ir(1)–O(6)
Ir(1)–C(18)
C(18)–C(19)
C(22)–C(23)
C(25)–Cl(1)
Ir(1)–N(7)
2.154(4)
2.025(4)
2.026(4)
2.099(3)
2.089(3)
2.031(5)
1.349(7)
1.514(8)
1.730(9)
–
2.142(5)
2.012(4)
2.027(4)
2.094(4)
2.069(4)
2.019(6)
1.350(8)
1.514(7)
–
–
Molecule 1
2.130(4)
2.031(5)
2.040(4)
–
2.047(4)
2.056(6)
1.349(8)
1.501(8)
–
2.068(4)
Molecule 2
2.134(4)
2.036(5)
2.038(4)
–
2.050(4)
2.039(6)
1.328(8)
1.507(8)
–
2.071(4)
Molecule 1
127.0(5)
112.7(5)
124.9(5)
110.1(5)
117.5(5)
89.16(18)
88.30(18)
87.80(17)
–
–
177.66(16)
93.16(16)
175.8(2)
91.46(16)
89.2(2)
88.6(2)
174.62(18)
91.66(19)
–
–
83.0(16)
96.1(2)
Molecule 2
125.8(5)
111.5(5)
124.5(5)
110.2(5)
118.5(5)
88.15(17)
88.34(17)
88.22(17)
–
–
178.23(17)
92.82(16)
177.0(2)
93.17(16)
90.2(2)
89.0(2)
174.20(18)
89.53(19)
–
–
86.11(16)
95.4(2)
Bond angles
O(7)–C(22)–O(6)
C(18)–C(17)–O(2)
C(18)–C(17)–O(3)
C(19)–C(20)–O(5)
C(19)–C(18)–C(17)
N(2)–Ir(1)–N(4)
N(2)–Ir(1)–N(6)
N(4)–Ir(1)–N(6)
N(2)–Ir(1)–O(1)
N(4)–Ir(1)–O(1)
N(2)–Ir(1)–O(6)
N(4)–Ir(1)–O(6)
N(6)–Ir(1)–C(18)
N(6)–Ir(1)–O(6)
N(4)–Ir(1)–C(18)
N(2)–Ir(1)–C(18)
N(4)–Ir(1)–N(7)
C(18)–Ir(1)–O(6)
O(6)–Ir(1)–O(1)
C(18)–Ir(1)–O(1)
O(6)–Ir(1)–N(7)
C(18)–Ir(1)–N(7)
126.4(5)
111.3(5)
124.2(5)
110.5(5)
118.6(4)
90.29(16)
88.68(16)
86.24(15)
88.49(15)
177.39(14)
176.98(14)
89.26(14)
176.15(17)
88.31(15)
90.63(17)
89.11(18)
126.2(6)
124.9(6)
111.8(6)
111.7(6)
119.4(6)
90.47(17)
86.44(18)
88.14(19)
178.91(16)
90.47(17)
86.44(18)
175.83(18)
175.40(2)
88.07(18)
89.1(2)
89.9(2)
93.89(17)
91.84(14)
91.65(17)
–
–
94.5(2)
91.47(16)
90.7(2)
–
–
15
Table 2. Crystal data for complexes 2d, 2h and 4a.
Compound
Empirical formula
Formula weight
Crystal colour and
shape
Crystal size (mm3)
Crystal system
Space group
Unit cell dimensions
a, Å
b, Å
c, Å
α, deg
β, deg
γ, deg
V, Å3
Z
Dcalcd, Mg m−3
μ, mm−1
2d
2h
C33 H47 B Cl Ir
C34 H50 B Ir N6 O7
N6 O7
878.23
857.81
4a
C34 H41 B Cl2 Ir N7
O6
917.65
Yellow prism
Yellow plate
Brown prism
0.3 × 0.2 × 0.1
Monoclinic
P2(1)/c
0.25 × 0.10 × 0.03
Monoclinic
P2(1)/c
0.31 × 0.26 × 0.17
Monoclinic
P2(1)/n
12.6199(10)
19.0261(15)
16.7046(13)
90
100.142(2)
90
3765.6(5)
4
1.549
3.669
Bruker SMART
Diffractometer
5000 CCD
Radiation
and λ(Mo
Kα),
wavelength
0.71073 Å
monochromator
Graphite
Scan type
ω
2θ
range
for
4.04 to 52.04
collection, (°)
T (K)
293(2)
−15 ≤ h ≤ 13;
Index ranges
−23 ≤ k ≤ 23;
−20 ≤ l ≤ 20
Reflections collected 24420
Independent
7395
reflections
(Rint = 0.0320)
5787
Observed reflections
(F > 4σ(F))
Parameters/restraints 450/0
R final; R all data
0.0334, 0.0498
19.1007(7)
16.8898(4)
11.4057(5)
20.4438(6)
19.8527(9)
22.0843(7)
90
90
116.907(2)
103.1530(1)
90
90
3856.8(3)
7425.5(4)
4
8
1.477
1.642
3.513
3.794
Enraf–Nonius
Bruker
SMART
Kappa CCD
5000 CCD
λ(Mo
Kα), λ(Mo
Kα),
0.71073 Å
0.71073 Å
graphite
Graphite
Ω
ω−ϕ
5.36 to 55.02
2.74–46.52°
293(2)
−24 ≤ h ≤ 18;
−14 ≤ k ≤ 13;
−23 ≤ l ≤ 25
18038
293(2) K
−13 ≤ h ≤ 18,
−22 ≤ k ≤ 22,
−24 ≤ l ≤ 24
71182
10489
7808 (Rint = 0.0435)
(Rint = 0.0677)
4942 (F > 4σ(F))
8423 (F > 4σ(F))
509/89
0.0489, 0.1005
975/0
0.0324, 0.0472
16
Compound
Rw final, Rw all
dataa
GOF (all data)
Max, min peaks
(e Å−3)
a
2d
2h
4a
0.0851, 0.0929
0.0769, 0.0897
0.0730, 0.0781
1.092
1.037
1.039
1.267, −0.812
1.392, −0.654
1.696, −0.964
where
.
17
Figure 1
18
Figure 2
19
Figure 3
20
Figure 4
21
Figure 5
22
Figure 6
23
Scheme 1
Scheme 1. Synthesis of Irida-E-alkenyl compounds 2a–h.
24
Scheme 2
Scheme 2. Irida E-alkenyl aqua complexes 3 and 3-d3.
25
Scheme 3
Scheme 3. Proposed stepwise formation of compounds 2 and 3.
26
Scheme 4
Scheme 4. The reaction of the Ir-derivative 2a with Lewis bases.
27
Scheme 5
Structure proposed of 4b′ and 4b″ complexes.
28