Synthesis, reactivities, and catalytic properties of iodo-bridged polymeric iridium complexes with flexible carbon chain-bridged bis(tetramethylcyclopentadienyl) ligands

Article abstract of DOI:10.1021/om4001742

Dinuclear iridium complexes [(C₅Me₄)(CH ₂)_n(C₅Me₄)][Ir(COD)]₂ (2a: n = 2; 2b: n = 3; 2c: n = 4) are obtained from the reactions of the corresponding dilithium salts Li₂

Full text of DOI:10.1021/om4001742

Article
pubs.acs.org/Organometallics
Synthesis, Reactivities, and Catalytic Properties of Iodo-Bridged
Polymeric Iridium Complexes with Flexible Carbon Chain-Bridged
Bis(tetramethylcyclopentadienyl) Ligands
Xing Tan,† Bin Li,† Shansheng Xu,† Haibin Song,† and Baiquan Wang*,†,‡
†State Key Laboratory of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China
‡State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences,
Shanghai 200032, China
S
* Supporting Information
ABSTRACT: Dinuclear iridium complexes [(C5Me4)(CH2)n-
(C5Me4)][Ir(COD)]2 (2a: n = 2; 2b: n = 3; 2c: n = 4) are
obtained from the reactions of the corresponding dilithium salts
Li2[(C5Me4)(CH2)n(C5Me4)] (n = 2−4) with [Ir(μ-Cl)(COD)]2.
Further oxidation of 2 affords iodo-bridged polymeric iridium
complexes [(C5Me4)(CH2)n(C5Me4)(IrI2)2]m (3a: n = 2; 3b: n =
3; 3c: n = 4). Dinuclear iridium complexes [(C5Me4)(CH2)n-
(C5Me4)][IrI2(PPh3)]2 (4a: n = 2; 4b: n = 3; 4c: n = 4) and
[(C5Me4)(CH2)n(C5Me4)][IrI2(CO)]2 (5b: n = 3; 5c: n = 4) are
obtained from the reactions of 3 with PPh3 and CO, respectively. Dinuclear dicarbonyl iridium complexes [(C5Me4)(CH2)n-
(C5Me4)][Ir(CO)2]2 (6b: n = 3; 6c: n = 4) are obtained from the reactions of 3 with Zn and CO. Additionally, the
cyclometalated dinuclear iridium complexes 7b,c, 8b,c, 9b,c, and 10b,c are obtained from the reactions of 3 with the
corresponding nitrogen ligands in the presence of KOH. The molecular structures of complexes 2a, 4a, 5b, 6c, and 7b have been
determined by single-crystal X-ray diffraction analysis. Moreover, we found that complexes 3 and 4 are efficient catalysts for the
selective amine cross-coupling reaction.
Chart 1
INTRODUCTION
■
Over the past decades, dinuclear metallocene complexes have
attracted significant interest in academic and industrial fields.1
In these complexes the two metal centers stay in close
proximity to offer the opportunity to produce cooperative
electronic and chemical interactions, and the complexes have
been envisaged to be useful for homogeneous catalysis.1b In
1969 Maitlis’s group reported [Cp*IrCl2]2 and Cp*Ir(CO)2 as
the first examples of half-sandwich Cp*Ir complexes (Cp* =
C5Me5).2 Recently, Cp*Ir complexes have been widely used in
the fields of organometallic chemistry,3,4 polymer chemistry,5
and organic chemistry,6 as fundamental reagents by virtue of
their properties. Although bridged cyclopentadienyliridium
dinuclear complexes have been reported,7 to the best of our
knowledge, these complexes have not been applied in catalysis.
Introduction of four methyl groups into the Cp rings of these
dinuclear complexes could improve their solubility in organic
solvents and reactivity. However, there is no report of a
dinuclear iridium complex with a bridged ligand connected to
the two C5Me4Ir fragments (Chart 1). Tethering two iridium
atoms to each other via a relatively short linkage might
encourage different catalytic properties compared to the
unlinked cyclopentadienyl complexes. Because the presence
of a carbocyclic structure in the hydrocarbyl chain will make the
chain rigid, we hope to use a flexible linear alkanediyl group (E
= (CH2)n) as a linker to directly connect the two C5Me4Ir
fragments.
In this paper, iodo-bridged polymeric iridium complexes
[(C5Me4)(CH2)n(C5Me4)(IrI2)2]m (n = 2−4) are synthesized
successfully. Furthermore, these iridium complexes are used as
the starting materials to synthesize a series of dinuclear iridium
complexes. Moreover, we studied the catalytic properties of
these iodo-bridged polymeric iridium complexes and derivative
dinuclear iridium complexes in the selective amine cross-
coupling reaction.
Received: March 1, 2013
Published: May 24, 2013
© 2013 American Chemical Society
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Scheme 1
η5-fashion with the cyclopentadienyl ring and in two η2-fashion
with cyclooctadiene. The molecular structure is unsymmetrical,
and the two cyclopentadienyl rings lie in the same direction.
The dihedral angle between the two cyclopentadienyl planes is
170.1°, indicating that the two cyclopentadienyl rings are
almost parallel.
RESULTS AND DISCUSSION
■
Preparation of Dinuclear Iridium Complexes [(C5Me4)-
(CH2)n(C5Me4)][Ir(COD)]2 (2a: n = 2; 2b: n = 3; 2c: n = 4).
To synthesize the iridium complexes, we chose the bifunctional
ligands C5Me4H(CH2)nC5Me4H (1a: n = 2; 1b: n = 3; 1c: n =
4) as the starting materials, in which (CH2)n was a flexible
linker to connect two tetramethylcyclopentadiene fragments.
Ligands 1a and 1b were prepared by Nazarov cyclization
reaction according to the literature methods.8,9 Ligand 1c was
prepared by the reaction of Grignard reagent with tetrame-
thylcyclopentenone, followed by hydrolysis and dehydration.
Mintz and co-workers also reported the synthesis of ligand
1b.10a Suzuki and co-workers obtained 1c from the reaction of
α,ω-dilithioalkane with tetramethylcyclopentenone, and they
used this ligand to synthesize bridged tetramethylcyclopenta-
dienyl ruthenium complexes.10b
Several dinuclear bis(cyclopentadienyl) iridium cycloocta-
diene complexes have been obtained from the reactions of the
corresponding dilithium salts with [Ir(μ-Cl)(COD)]2 in THF
at room temperature or refluxing temperature.7 However, we
failed to isolate the corresponding products from
Li2[C5Me4(CH2)nC5Me4] with [Ir(μ-Cl)(COD)]2 under
these reaction conditions. Fortunately, we obtained the
dinuclear iridium cyclooctadiene complexes 2 in refluxing
xylene in low to moderate yields (Scheme 1).
Preparation of Iodo-Bridged Polymeric Iridium Com-
plexes [(C5Me4)(CH2)n(C5Me4)(IrI2)2]m (3a: n = 2; 3b: n = 3;
3c: n = 4). Complexes 2 were easily oxidized by iodine in
CH2Cl2 and gave the dark red diiodo iridium(III) complexes 3
in good yields. The elemental analysis suggested that it should
be an organometallic polymer, linked by Ir−I−Ir bridges as
shown in Scheme 1. Complexes 3 are almost insoluble in all
1
organic solvents. In the H NMR spectra of 3 in DMSO-D6
solution, the signals associated with the methyl protons on the
C5 rings appeared at around 1.9 ppm as two singlet peaks close
to each other with an integral intensity of 12H. It is possible
that DMSO-D6 could cleave the iodo-bridges to form the
dinuclear iridium complexes [(C5Me4)(CH2)n(C5Me4)]-
[IrI2(DMSO-D6)]2. The reported halogen-bridged polymeric
iridium and rhodium complexes show similar insolubility in a
wide variety of organic solvents.7,11
Preparation of Dinuclear Iridium Complexes [(C5Me4)-
(CH2)n(C5Me4)][IrI2(PPh3)]2 (4a: n = 2, 4b: n = 3; 4c: n = 4)
and [(C5Me4)(CH2)n(C5Me4)][IrI2(CO)]2 (5b: n = 3; 5c: n =
4). To further characterize complexes 3, we used two different
ligands, PPh3 and CO, to dissociate the iodo-bridged polymeric
complexes. As shown in Scheme 2, dinuclear complexes
In the 1H NMR spectra of complexes 2, the signals associated
with the methyl protons on the C5 rings appeared at around 1.8
ppm as two singlet peaks close to each other with an integral
intensity of 12H. The structure of 2a was confirmed by single-
crystal X-ray diffraction studies, which is depicted in Figure 1
with selected bond lengths. Complex 2a possesses two
(C5Me4)Ir(COD) fragments, linked by a (CH2)2 chain with
cis-configuration. In each fragment, the Ir atom is bounded in
Scheme 2
[(C5Me4)(CH2)n(C5Me4)][IrI2(PPh3)]2 (4a: n = 2; 4b: n =
3; 4c: n = 4) were easily obtained by reactions of 3 with PPh3 in
CH2Cl2 at room temperature for 2 h in almost quantitative
yield as orange-yellow solids. In the 1H NMR spectra of
complexes 4, the signals associated with the methyl protons on
the C5 rings appeared at around 1.73 and 1.56 ppm as two
singlets or doublets with an integral intensity of 12H. The
31P{1H} NMR spectra of 4 showed only one phosphorus at
around δ −9.5 ppm, which is similar to the reported
mononuclear analogue (C5Me4H)IrI2(PPh3) (δ −8.2 ppm).12
The structure of 4a was confirmed by single-crystal X-ray
diffraction studies and is depicted in Figure 2 with selected
bond lengths and angles. Complex 4a possesses two three-
legged half-sandwich (C5Me4)IrI2(PPh3) fragments linked by a
Figure 1. ORTEP view of [(C5Me4)(CH2)2(C5Me4)][Ir(C8H12)]2
(2a) showing 60% ellipsoids. Hydrogen atoms have been omitted for
clarity. Selected bond distances (Å): Ir(1)−C(1) 2.106(7), Ir(1)−
C(4) 2.103(6), Ir(1)−C(5) 2.119(6), Ir(1)−C(8) 2.099(6), Ir(2)−
C(29) 2.117(6), Ir(2)−C(32) 2.115(6), Ir(2)−C(33) 2.101(6),
Ir(2)−C(36) 2.119(6), Ir(1)···Ir(2) 6.505.
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Figure 3. ORTEP view of [(C5Me4)(CH2)3(C5Me4)][IrI2(CO)]2
(5b) showing 30% ellipsoids. Hydrogen atoms have been omitted
for clarity. Selected bond distances (Å) and angles (deg): Ir(1)−C(1)
2.106(7), Ir(1)−I(1) 2.7013(6), Ir(1)−I(2) 2.7040(6), Ir(2)−C(2)
1.888(6), Ir(2)−I(3) 2.6846(7), Ir(2)−I(4) 2.6743(6), Ir(1)···Ir(2)
9.001, C(1)−Ir(1)−I(1) 90.8(2), C(1)−Ir(1)−I(2) 88.9(2), I(1)−
Ir(1)−I(2) 91.10(2), C(2)−Ir(2)−I(3) 87.7(2), C(2)−Ir(2)−I(4)
88.2(2), I(3)−Ir(2)−I(4) 90.53(2).
Figure 2. ORTEP view of [(C5Me4)(CH2)2(C5Me4)][IrI2(PPh3)]2
(4a) showing 30% ellipsoids. Hydrogen atoms have been omitted for
clarity. Selected bond distances (Å) and angles (deg): Ir(1)−P(1)
2.316(1), Ir(1)−I(1) 2.6956(7), Ir(1)−I(2) 2.6974(8), Ir(1)···Ir(1A)
7.953, I(1)−Ir(1)−I(2) 93.02(2), I(1)−Ir(1)−P(1) 91.93(3), I(2)−
Ir(1)−P(1) 88.85(3).
(CH2)2 chain, with Ci symmetry. The IrI2(PPh3) fragments are
positioned on the Cp faces of the bridging ligand so that inter-
ring repulsions are minimized. This results in a long interatomic
separation of Ir(1)···Ir(2) = 7.953 Å, significantly longer than
the corresponding distance in complex 2a [Ir(1)···Ir(2) = 6.505
Å], which may result from steric hindrance of the IrI2(PPh3)
fragments.
The further reactivity search of complex 3a was not carried
out owing to the very poor yield of 2a. Similarly, dinuclear
complexes [(C5Me4)(CH2)n(C5Me4)][IrI2(CO)]2 (5b,c, n = 3,
4) were obtained by reactions of 3 with CO in CH2Cl2 at room
temperature for 2 h (Scheme 3). Complex 5b is an orange-red
resulting mixture was extracted with hexane and dried. Removal
of solvent under reduced pressure afforded the dinuclear
dicarbonyliridium complexes [(C5Me4)(CH2)n(C5Me4)][Ir-
(CO)2]2 (6b,c, n = 3, 4) as yellow microcrystalline solids in
good yields (Scheme 4).
Scheme 4
Scheme 3
1
In the H NMR spectra of a C6D6 solution of complexes 6,
the signals associated with the methyl protons on the C5 rings
appear at around 1.8 ppm as two singlets close to each other
with an integral intensity of 12H. The signals around δ 177
ppm in the 13C NMR spectra of 6 clearly reveal the presence of
terminal carbonyl ligands. The IR spectra of 6 show two
absorption peaks attributable to stretching vibration of the
terminal carbonyl absorptions around 2000 and 1930 cm−1.
The structure of 6c was confirmed by single-crystal X-ray
diffraction studies and is depicted in Figure 4 with selected
bond lengths and angles.
solid and is easily soluble in halogenated hydrocarbons such as
chloroform and dichloromethane. In contrast, complex 5c is a
yellow solid and is barely soluble even in chloroform and
1
dichloromethane. In the H NMR spectra of complexes 5, the
signals associated with the methyl protons on the C5 rings
appeared at around 2.2 ppm as two singlets close to each other
with an integral intensity of 12H. Additionally, the IR spectra of
5 show only one absorption peak attributable to stretching
vibration of terminal carbonyl absorptions around 2020 cm−1.
The structure of 5b was confirmed by single-crystal X-ray
diffraction studies and is depicted in Figure 3 with selected
bond lengths and angles.
Preparation of Cyclometalated Dinuclear Iridium
Complexes 7b,c, 8b,c, 9b,c, and 10b,c. The first example
Preparation of Dinuclear Dicarbonyl Iridium Com-
plexes [(C5Me4)(CH2)n(C5Me4)][Ir(CO)2]2 (6b: n = 3; 6c: n =
4). Graham’s group had reported the synthesis of Cp*Ir(CO)2
from reducing [Cp*IrCl2]2 with Zn powder in the presence of
high-pressure CO.3c This method was applied successfully to
synthesize dinuclear dicarbonyl iridium complexes 6 with some
improvements. The suspension of complexes 3 and Zn powder
in CH3OH was bubbled by CO at 65 °C for 5 h to give a pale
yellow solution. After cooling to room temperature, an aqueous
solution of NaOH saturated with NaCl was added. Then the
Figure 4. ORTEP view of [(C5Me4)(CH2)4(C5Me4)][Ir(CO)2]2 (6c)
showing 30% ellipsoids. Hydrogen atoms have been omitted for
clarity. Selected bond distances (Å) and angles (deg): Ir(1)−C(1)
1.838(6), Ir(1)−C(2) 1.834(7), Ir(1)···Ir(1A) 10.465, C(1)−Ir(1)−
C(2) 89.3(2).
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Scheme 5
of the Cp*Ir complex with a cyclometalated nitrogen donor
ligand was reported by Beck and co-workers in 1998, using
[Cp*IrCl2]2 and NaOAc.4a After that, [Cp*IrCl2]2 has been
established as a starting material to synthesize many cyclo-
metalated iridium complexes.4
Because of the well-established cyclometalated Cp*Ir
complex with 2-phenylpyridine,4g our initial study focused on
the reactions of complexes 3 with this ligand. However, we
failed to obtain the cyclometalated product in the presence of
NaOAc. When these reactions were carried out in refluxing
CH3CN in the presence of KOH, the cyclometalated dinuclear
iridium complexes 7b,c were obtained as a yellow solid in
moderate to good yield (Scheme 5). The 1H NMR spectra of 7
clearly show eight protons, as expected for the orthometalated
ligand, which is similar to that of the reported analogous
mononuclear Cp*Ir complex.13 The structure of 7b was
confirmed by single-crystal X-ray diffraction studies and is
depicted in Figure 5 with selected bond lengths and angles.
Complex 7b possesses two inequivalent (C5Me4)Ir fragments,
linked by a (CH2)3 chain. The (C5Me4)Ir fragments adopt a
three-legged piano-stool geometry, and the two cyclopenta-
dienyl rings are criss-crossed with each other at a dihedral angle
of 72.3°. The Ir−I bond lengths are 2.6895(9) and 2.689(1) Å,
the Ir−N bond lengths are 2.079(4) and 2.068(4) Å, and Ir−C
(phenyl pyridine) lengths are 2.041(5) and 2.008(2) Å. These
values are close to that of the corresponding analogous
Figure 5. ORTEP view of 7b showing 30% ellipsoids. Hydrogen atoms
have been omitted for clarity. Selected bond distances (Å) and angles
(deg): Ir(1)−N(1) 2.079(4), Ir(1)−C(28) 2.041(5), Ir(1)−I(1)
2.6895(9), Ir(2)−N(2) 2.068(4), Ir(2)−C(39) 2.008(2), Ir(2)−I(2)
2.689(1), Ir(1)···Ir(2) 7.761, N(1)−Ir(1)−C(28) 78.6(2), N(2)−
Ir(2)−C(39) 77.0(2).
shows several signals in the range δ 1.81−1.69 for the methyl
groups, due to its unsymmetrical structure.
Similarly, cyclometalated dinuclear iridium complexes 8b,c,
9b,c, and 10b,c were obtained from the reactions of complexes
1
3 and the corresponding ligands. The H NMR spectra of
complexes 8−10 also agree with the cyclometalated structures.
These results indicated that pyridine, imine, and dihydroimi-
dazole can act as good directing groups in the cyclometalated
reactions of complexes 3.
mononuclear Cp*Ir complex.13 The H NMR spectrum of 7b
1
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Catalytic Studies. Complexes 3 and [Cp*IrI2]2 may
possess similar catalytic properties owing to their analogous
structures. Williams’s group reported that [Cp*IrI2]2 could
serve as an efficient catalyst in the selective amine cross-
coupling reaction.6g Complexes 3 were evaluated as catalyst
precursors in this reaction, and the catalytic results are
summarized in Table 1.
filtration owing to their very poor solubility. Then we turned
our attention to the recyclability. In the N-alkylation of 4-
methoxyaniline with 3b as the catalyst under the conditions
listed in Table 1, the iridium complex can be recycled easily.
The initial three cycles afforded the corresponding product in
high yields (Table 2). However, the yield dramatically
Table 2. Recycling of Catalyst 3b for N-Alkylation of 4-
Methoxyaniline
Table 1. N-Alkylation of Aniline Catalyzed by Iridium
a
Complexes
cycle
0
1
2
3
4
entry
cat.
amine substrate
product
yield (%)
yield (%)
99
99
98
89
56
1
3a
3b
3c
3b
3b
3b
3b
3b
3b
3b
3b
3b
4-MeOC6H4NH2
4-MeOC6H4NH2
4-MeOC6H4NH2
C6H5NH2
11
11
11
12
13
14
15
16
17
18
19
20
11
11
11
11
11
11
99
99
99
99
95
99
25
96
98
80
83
96
99
96
31
84
96
65
2
3
decreased in the fourth cycle, with most of the iridium complex
converted to a black solid. This black solid is not soluble even
in DMSO, and it may be formed from decomposition of the
iridium catalyst.
4
5
4-ClC6H4NH2
6
4-MeC6H4NH2
4-O2NC6H4NH2
3-ClC6H4NH2
7
CONCLUSION
8
■
9
3-MeC6H4NH2
2-MeC6H4NH2
2-MeOC6H4NH2
C6H5CH2NH2
In summary, iodo-bridged polymeric iridium complexes 3a−c
[(C5Me4)(CH2)n(C5Me4)(IrI2)2]m (n = 2−4) were synthesized
successfully by the reactions of dilithium salts Li2[(C5Me4)-
(CH2)n(C5Me4)] with [Ir(μ-Cl)(COD)]2, followed by oxida-
tion by iodine. Complexes 3 could serve as starting material to
synthesize a series of dinuclear iridium complexes [(C5Me4)-
(CH2)n(C5Me4)][IrI2(PPh3)]2 (4a−c), [(C5Me4)(CH2)n-
(C5Me4)][IrI2(CO)]2 (5b,c), and [(C5Me4)(CH2)n(C5Me4)]-
[Ir(CO)2]2 (6b,c). Additionally, the cyclometalated dinuclear
iridium complexes 7b,c, 8b,c, 9b,c, and 10b,c could be obtained
by the reactions of complexes 3 with corresponding ligands in
refluxing CH3CN in the presence of KOH. Moreover, we found
that complexes 3 and 4 could serve as efficient catalysts in the
selective amine cross-coupling reaction. The study of
recyclability of 3 indicated that the recovered catalyst only
had good activity in the initial three cycles. Our further research
of these dinuclear iridium complexes both in stoichiometry and
in catalysis is still in progress.
10
11
12
13
14
15
16
[Cp*IrI2]2
4-MeOC6H4NH2
4-MeOC6H4NH2
4-MeOC6H4NH2
4-MeOC6H4NH2
4-MeOC6H4NH2
4-MeOC6H4NH2
4b
5b
Cp*Ir(PPh3)I2
4b
b
17
b
18
Cp*Ir(PPh3)I2
a
Reaction conditions: amine substrate RNH2 (1 mmol), (iPr)2NH (3
mmol), xylene (2 mL), catalyst (2 mol % Ir), 155 °C, 10 h. Yields of
isolated products are based on amine substrates. T = 140 °C.
b
The reactions were carried out using a catalyst loading of 2
mol % Ir in xylene at 155 °C. We first examined the N-
alkylation of 4-methoxyaniline with diisopropylamine catalyzed
by three iodo-bridged polymeric iridium complexes, 3a−c.
Encouragingly, excellent yields were obtained by using any of
them. Then we investigated N-alkylation of a range of amines
with diisopropylamine by using 3b as the catalyst. In most
cases, the N-isopropylamine was isolated in excellent yield.
However, the electron-deficient (Table 1, entry 7) and ortho-
substituted (Table 1, entries 10, 11) aniline led to a lower yield.
Moreover, benzylamine (Table 1, entry 12) could also react
nicely with diisopropylamine. These results indicated that the
catalytic activities of complexes 3 were similar to that of
[Cp*IrI2]2 (ref 6g and Table 1, entry 13). The catalytic
activities of dinuclear complexes 4b and 5b in the N-alkylation
of 4-methoxyaniline with diisopropylamine were also studied.
The yield using 4b as the catalyst is excellent, while the yield
using 5b as the catalyst is much lower (Table 1, entries 14, 15).
Compared to dinuclear complex 4b, the monometallic analogue
Cp*Ir(PPh3)I2 afforded a lower yield (Table 1, entry 16).
When the reaction temperature was decreased to 140 °C, the
catalytic activity of 4b was significantly better than that of its
monometallic analogue (Table 1, entries 17, 18).
EXPERIMENTAL SECTION
General Considerations. Schlenk- and vacuum-line techniques
■
were employed for all manipulations. All solvents were distilled from
appropriate drying agents under argon before use. H, 13C, and 31P
1
NMR spectra were recorded using a Bruker AV400 spectrometer. IR
spectra were recorded as KBr disks on a Bruker TENSOR 27
spectrometer. Elemental analyses were performed on a Perkin-Elmer
240C analyzer. ESI mass spectra were measured on a Finnigan LCQ
Advantage instrument. Compounds 1a,8 1b,9 and [Ir(μ-Cl)(COD)]2
14
were prepared by literature methods.
Preparation of (C5Me4H)(CH2)4(C5Me4H) (1c). To a 250 mL
three-necked flask, equipped with a reflux condenser, a constant
pressure funnel, and a large magnetic stirrer bar, were added THF (80
mL) and Mg (1.70 g, 70.0 mmol). Then a mixture of Br(CH2)4Br
(7.68 g, 35 mmol) and THF (15 mL) was added dropwise to the
solution as required for initiation of the Grignard reaction. After the
reaction began, this solution was added at a rate that caused reflux of
the solvent. The reaction mixture was then heated under reflux for 1 h.
To another 250 mL three-necked flask, equipped with a reflux
condenser, a constant pressure funnel, and a magnetic stirrer bar, were
added 2,3,4,5-tetramethylcyclopent-2-en-1-one (10.0 g, 72.5 mmol)
and THF (30 mL). The reaction mixture was cooled to 0 °C, and the
When catalysts 3 were used in this reaction, the iridium
complex could be removed from the reaction mixture by simple
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Grignard reagent was added dropwise to the solution. After the
addition was complete, the solution was stirred overnight at room
temperature and then refluxed for another 3 h. The resulting
suspension was cooled to room temperature and quenched with 6
M HCl aqueous solution (100 mL). The mixture was stirred
vigorously for 6 h. The aqueous phase was extracted three times
with 50 mL of diethyl ether, and the combined ether fraction was dried
over MgSO4. The solvents and excess tetramethylcyclopentenone were
removed in vacuo. The resultant brown, oily product was purified by
column chromatography on silica gel with petroleum ether as the
eluent. Evaporation of the eluate afforded 1c as a yellow oil (7.5 g,
72%). 1H NMR (CDCl3): δ 2.59−2.12 (m, 6H, C5Me4CH2 and
C5Me4H), 1.82−1.78 (m, 18H, C5Me4), 1.3 (m, 4H, CH2), 1.02−0.86
(m, 6H, C5Me4). ESI-MS (m/z): 298 [M]+. This spectroscopic data
are much closer to that reported by Suzuki.10b
Preparation of Dinuclear Iridium Complexes 2a−c, [(C5Me4)-
(CH2)n(C5Me4)][Ir(COD)]2 (2a: n = 2; 2b: n = 3; 2c: n = 4). A
solution of 1b (329 mg, 1.16 mmol) in hexane (20 mL) was treated
with 1.03 mL of n-BuLi (2.25 M, 2.32 mmol) in 0 °C, and the mixture
was refluxed overnight to give a white precipitate. The solvent was
removed in vacuo, and then xylene (20 mL) was added. The mixture
was cooled to 0 °C, and then [Ir(μ-Cl)(COD)]2 (779 mg, 1.16 mmol)
was added. The reaction mixture was refluxed for 24 h to give a dark
solution. The reaction solvent was removed in vacuo, and the residue
was chromatographed on a short alumina column with petroleum
ether as eluent to give a white solid, 2b (420 mg, 42%). By using
similar procedures, 2a and 2c could be obtained in 5% and 36% yields,
respectively.
Compound 3c (n = 4). Mp: >300 °C. Anal. Calcd for C22H32I4Ir2:
C, 22.23; H, 2.71. Found: C, 22.29; H, 2.69. 1H NMR (DMSO-d6): δ
2.34 (m, 4H, CH2CH2CH2CH2), 1.93 (s, 12H, C5Me4), 1.89 (s, 12H,
C5Me4), 1.50 (m, 4H, CH2CH2CH2CH2).
Preparation of Dinuclear Iridium Complexes [(C5Me4)(CH2)n-
(C5Me4)][IrI2(PPh3)]2 (4a: n = 2, 4b: n = 3; 4c: n = 4). A suspension
of 3b (50 mg, 0.0426 mmol) and PPh3 (23 mg, 0.0877 mmol) in 20
mL of CH2Cl2 was stirred for 2 h to give a red solution. After removal
of solvent in vacuo the residue was washed with ether three times to
give an orange solid, 4b (68 mg, 94%). By using similar procedures, 4a
and 4c also could be obtained as orange solids in 95% and 97% yields,
respectively.
Compound 4a (n = 2). Mp: >300 °C. Anal. Calcd for
C56H58I4Ir2P2: C, 39.92; H, 3.47. Found: C, 40.07; H, 3.53. 1H
NMR (CDCl3): δ 7.76 (s, 4H, Ph-H), 7.60 (m, 8H, Ph-H), 7.46 (m,
12H, Ph-H), 7.26 (s, 6H, Ph-H), 2.17 (s, 4H, (CH2)2), 1.78 (s, 12H,
C5Me4), 1.53 (s, 12H, C5Me4). 31P NMR (CDCl3): δ −9.6 (s). ESI-MS
(m/z): 1559 ([M − I]+, based on 193Ir).
Compound 4b (n = 3). Mp: 242−243 °C. Anal. Calcd for
1
C57H60I4Ir2P2: C, 40.29; H, 3.56. Found: C, 40.17; H, 3.47. H NMR
(CDCl3): δ 7.77 (s, 4H, Ph-H), 7.59 (t, J = 8.2 Hz, 8H, Ph-H), 7.44−
7.42 (m, 12H, Ph-H), 7.23 (s, 6H, Ph-H), 2.03 (t, J = 7.5 Hz, 4H,
CH2CH2CH2), 1.69 (d, JPH = 1.4 Hz, 12H, C5Me4), 1.56 (d, JPH = 1.2
Hz, 12H, C5Me4), 1.42−1.40 (m, 2H, CH2CH2CH2). 31P NMR
(CDCl3): δ −9.4 (s). ESI-MS (m/z): 1573 ([M − -I]+, based on 193Ir).
Compound 4c (n = 4). Mp: >300 °C. Anal. Calcd for
C58H62I4Ir2P2: C, 40.66; H, 3.65. Found: C, 40.59; H, 3.70. 1H
NMR (CDCl3): δ 7.78 (m, 4H, Ph-H), 7.60 (t, J = 8.3 Hz, 8H, Ph-H),
7.44−7.43 (m, 12H, Ph-H), 7.23 (s, 6H, Ph-H), 1.96 (t, J = 6.5 Hz,
4H, CH2CH2CH2CH2), 1.72 (d, JPH = 1.9 Hz, 12H, C5Me4), 1.59 (d,
JPH = 1.8 Hz, 12H, C5Me4), 1.31 (m, 4H, CH2CH2CH2CH2). 31P
NMR (CDCl3): δ −9.4 (s). ESI-MS (m/z): 1587 ([M − I]+, based on
193Ir).
Preparation of Dinuclear Diiodo(carbonyl) Iridium Com-
plexes [(C5Me4)(CH2)n(C5Me4)][IrI2(CO)]2 (5b: n = 3; 5c: n = 4). A
suspension of 3b (63 mg, 0.0536 mmol) in 15 mL of CH2Cl2 was
bubbled by CO at room temperature for 2 h to give a red solution.
Removal of solvent in vacuo gave an orange-red solid, 5b (63 mg,
96%). By using similar procedures, 5c also could be obtained as a
yellow solid in 95% yield.
Compound 2a (n = 2). Mp: 267−268 °C. Anal. Calcd for
1
C36H52Ir2: C, 49.74; H, 6.03. Found: C, 49.66; H, 5.97. H NMR
(CDCl3): δ 2.76 (d, J = 2.8 Hz, 8H, CH(COD)), 2.29 (s, 4H,
(CH2)2), 2.01−1.98 (m, 8H, CH2(COD)), 1.86 (s, 12H, C5Me4),
1.78−1.76 (m, 8H, CH2(COD)), 1.75 (s, 12H, C5Me4). 13C NMR
(100 MHz, CDCl3): δ 95.0 (C5(CH3)4), 92.2 (C5Me4), 90.3 (C5Me4),
51.8 (CH(COD)), 33.1, 26.0, 8.3 (C5Me4), 7.8 (C5Me4). ESI-MS (m/
z): 871 ([M + H]+, based on 193Ir).
Compound 2b (n = 3). Mp: 179−180 °C. Anal. Calcd for
1
C37H54Ir2: C, 50.31; H, 6.16. Found: C, 50.25; H, 6.09. H NMR
(CDCl3): δ 2.75 (s, 8H, CH(COD)), 2.19 (t, J = 7.3 Hz, 4H,
CH2CH2CH2), 1.98 (m, 8H, CH2(COD)), 1.85 (s, 12H, C5Me4), 1.78
(m, 20H, C5Me4 and CH2(COD)), 1.54 (m, 2H, CH2CH2CH2). 13C
NMR (100 MHz, CDCl3): δ 96.1 (C5Me4), 92.9 (C5Me4), 91.3
(C5Me4), 52.8 (CH(COD)), 34.2, 33.3, 24.8, 9.3 (C5Me4), 9.0
(C5Me4). ESI-MS (m/z): 885 ([M + H]+, based on 193Ir).
Compound 5b (n = 3). Mp: 217−218 °C. Anal. Calcd for
1
C23H30I4Ir2O2: C, 22.45; H, 2.46. Found: C, 22.63; H, 2.50. H NMR
(CDCl3): δ 2.51 (m, 4H, CH2CH2CH2), 2.26 (s, 12H, C5Me4), 2.21
(s, 12H, C5Me4), 1.75 (m, 2H, CH2CH2CH2). IR (νCO, cm−1): 2025
(s).
Compound 5c (n = 4). Mp: >300 °C. Anal. Calcd for
C24H32I4Ir2O2: C, 23.16; H, 2.59. Found: C, 22.95; H, 2.52. 1H
NMR (CDCl3): δ 2.44 (m, 4H, CH2CH2CH2CH2), 2.26 (s, 12H,
C5Me4), 2.21 (s, 12H, C5Me4), 1.68 (m, 4H, CH2CH2CH2CH2). IR
(νCO, cm−1): 2022 (s).
Preparation of Dinuclear Dicarbonyl Iridium Complexes
[(C5Me4)(CH2)n(C5Me4)][Ir(CO)2]2 (6b: n = 3; 6c: n = 4). A
suspension of 3b (100 mg, 0.0851 mmol) and Zn powder (60 mg,
0.918 mmol) in 30 mL of CH3OH was bubbled by CO at 65 °C for 5
h to give a pale yellow solution. After cooling to room temperature, an
aqueous solution of NaOH saturated with NaCl (15 mL, argon
sparged) was transferred via cannula to the solution, and it was stirred
for 20 min. The mixture was extracted with 4 × 10 mL of hexane. The
extracts were combined and dried by MgSO4 for 2 h. The solution was
filtered, and the solvent was removed in vacuo to give a yellow solid,
6b (54 mg, 81%). By using similar procedures, 6c could be obtained as
a yellow solid in 78% yield.
Compound 2c (n = 4). Mp: 231−232 °C. Anal. Calcd for
1
C38H56Ir2: C, 50.87; H, 6.29. Found: C, 50.94; H, 6.37. H NMR
(CDCl3): δ 2.74 (d, J = 2.7 Hz, 8H, CH(COD)), 2.16 (t, J = 6.9 Hz,
4H, CH2CH2CH2CH2), 2.00−1.98 (m, 8H, CH2(COD)), 1.85 (s,
12H, C5Me4), 1.79 (s, 12H, C5Me4), 1.76 (m, 8H, CH2(COD)), 1.46
(m, 4H, CH2CH2CH2CH2). 13C NMR (100 MHz, CDCl3): δ 96.5
(C5Me4), 92.8 (C5Me4), 91.4 (C5Me4), 58.3 (CH(COD)), 52.8
(CH(COD)), 34.1, 31.7, 24.6, 18.3, 9.3 (C5Me4), 9.1 (C5Me4). ESI-MS
(m/z): 899 ([M + H]+, based on 193Ir).
Preparation of Iodo-Bridged Polymeric Iridium Complexes
[(C5Me4)(CH2)n(C5Me4)(IrI2)2]m (3a: n = 2; 3b: n = 3; 3c: n = 4). To
a solution of 2b (300 mg, 0.340 mmol) in 40 mL of CH2Cl2 was added
dropwise 175 mg (0.690 mmol) of I2 in 50 mL of CH2Cl2, and the
mixture was stirred for 3 days to give a dark red suspension. The
reaction solvent was removed in vacuo, and the residue was washed
with CH2Cl2 three times to give a dark red solid 3b (351 mg, 88%). By
using similar procedures, 3a and 3c could be obtained in 84% and 87%
yields, respectively.
Compound 3a (n = 2). Mp: >300 °C. Anal. Calcd for C20H28I4Ir2:
C, 20.70; H, 2.43. Found: C, 20.83; H, 2.45. 1H NMR (DMSO-d6): δ
2.37 (s, 4H, (CH2)2), 1.94 (s, 12H, C5Me4), 1.91 (s, 12H, C5Me4).
Compound 3b (n = 3). Mp: >300 °C. Anal. Calcd for C21H30I4Ir2:
C, 21.47; H, 2.57. Found: C, 21.41; H, 2.63. 1H NMR (DMSO-d6): δ
2.33 (t, J = 7.8 Hz, 4H, CH2CH2CH2), 1.92 (s, 12H, C5Me4), 1.88 (s,
12H, C5Me4), 1.56 (m, 2H, CH2CH2CH2).
Compound 6b (n = 3). Mp: 88−90 °C. Anal. Calcd for
1
C25H32Ir2O4: C, 38.45; H, 4.13. Found: C, 38.69; H, 4.22. H NMR
(C6D6): δ 2.19 (t, J = 8.1 Hz, 4H, CH2CH2CH2), 1.86 (s, 12H,
C5Me4), 1.80 (s, 12H, C5Me4), 1.35 (m, 2H, CH2CH2CH2). 13C NMR
(100 MHz, C6D6): δ 177.8 (CO), 102.4 (C5(CH3)4), 97.6
(C5(CH3)4), 96.4 (C5(CH3)4), 37.3 (CH2CH2CH2), 25.0
(CH2CH2CH2), 10.3 (C5Me4). IR (νCO, cm−1): 1999 (s), 1926 (s).
ESI-MS (m/z): 781 ([M + H]+, based on 193Ir).
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Organometallics
Article
Compound 6c (n = 4). Mp: 151−152 °C. Anal. Calcd for
Compound 9c (n = 4). Mp: >300 °C. Anal. Calcd for
C48H52I2Ir2N2: C, 44.51; H, 4.05. Found: C, 44.63; H, 4.01. 1H
NMR (CDCl3): δ 8.49 (d, J = 5.7 Hz, 2H, HCN), 7.58 (d, J = 7.3
Hz, 2H, Ar-H), 7.40 (t, J = 7.5 Hz, 2H, Ar-H), 7.31−7.19 (m, J = 8H,
Ar-H), 6.96 (s, 2H, Ar-H), 6.72 (t, J = 6.4 Hz, 2H, Ar-H), 1.78 (m, 4H,
CH2CH2CH2CH2), 1.63−1.52 (m, 24H, C5Me4), 1.22 (m, 4H,
CH2CH2CH2). ESI-MS (m/z): 1169 ([M − I]+, based on 193Ir).
Preparation of Cyclometalated Dinuclear Iridium Complexs
10b,c. A solution of 3b (80.0 mg, 0.0681 mmol), 2-phenyl-4,5-
dihydro-1H-imidazole (23.8 mg, 0.163 mmol), and KOH (11.2 mg,
0.200 mmol) in 30 mL of CH3CN was refluxed for 24 h. After
filtration through Celite the filtrate was concentrated and further
purified via neutral alumina gel chromatography with CH2Cl2/acetone
(20:1) to give a yellow solid, 10b (51 mg, 62%). By using similar
procedures, 10c could be obtained as a yellow solid in 58% yield.
Compound 10b (n = 3). Mp: >300 °C. Anal. Calcd for
C39H48I2Ir2N4: C, 38.68; H, 3.99. Found: C, 38.40; H, 4.01. 1H
NMR (CDCl3): δ 7.68 (d, J = 7.5 Hz, 2H, C6H4), 7.25 (d, J = 7.6 Hz,
2H, C6H4), 7.12 (t, J = 6.9 Hz, 2H, C6H4), 6.88 (t, J = 7.1 Hz, 2H,
C6H4), 5.36 (s, 2H, NH), 3.87 (t, J = 9.3 Hz, 4H, (CH2)2), 3.71−3.64
(m, 2H, (CH2)2), 3.50−3.45 (m, 2H, (CH2)2), 2.19 (m, 4H,
CH2CH2CH2), 1.86−1.78 (m, 24H, C5Me4), 1.47 (m, 2H,
CH2CH2CH2). ESI-MS (m/z): 1085 ([M − I]+, based on 193Ir).
Compound 10c (n = 4). Mp: >300 °C. Anal. Calcd for
C40H50I2Ir2N4: C, 39.22; H, 4.11. Found: C, 39.01; H, 3.98. 1H
NMR (CDCl3): δ 7.70 (d, J = 7.5 Hz, 2H, C6H4), 7.19 (d, J = 7.5 Hz,
2H, C6H4), 7.14 (t, J = 7.2 Hz, 2H, C6H4), 6.89 (t, J = 7.4 Hz, 2H,
C6H4), 5.11 (s, 2H, NH), 3.96 (t, J = 9.1 Hz, 4H, (CH2)2), 3.82 (t, J =
9.1 Hz, 4H, (CH2)2), 2.17 (m, 4H, CH2CH2CH2CH2), 1.87−1.83 (m,
24H, C5Me4), 1.45 (m, 4H, CH2CH2CH2CH2). ESI-MS (m/z): 1099
([M − I]+, based on 193Ir).
1
C26H34Ir2O4: C, 39.28; H, 4.31. Found: C, 39.53; H, 4.38. H NMR
(C6D6): δ 2.18 (t, J = 7.0 Hz, 4H, CH2CH2CH2CH2), 1.87 (s, 12H,
C5Me4), 1.80 (s, 12H, C5Me4), 1.38 (m, 4H, CH2CH2CH2CH2). 13C
NMR (100 MHz, C6D6): δ 176.6 (CO), 102.4 (C5Me4), 96.2
(C5Me4), 95.1 (C5Me4), 33.1 (CH2CH2CH2CH2), 23.4
(CH2CH2CH2CH2), 9.0 (C5Me4). IR (νCO, cm−1): 2005 (s), 1937
(s). ESI-MS (m/z): 795 ([M + H]+, based on 193Ir).
Preparation of Cyclometalated Dinuclear Iridium Complexs
7b,c. A solution of 3b (80.0 mg, 0.0681 mmol), 2-phenylpyridine
(25.3 mg, 0.163 mmol), and KOH (11.2 mg, 0.200 mmol) in 30 mL of
CH3CN was refluxed for 24 h. After filtration through Celite the
filtrate was concentrated and further purified via neutral alumina gel
chromatography with CH2Cl2 to give a yellow solid, 7b (38 mg, 45%).
By using similar procedures, 7c could be obtained as a yellow solid in
51% yield.
Compound 7b (n = 3). Mp: >300 °C. Anal. Calcd for
C43H46I2Ir2N2: C, 42.02; H, 3.77. Found: C, 42.11; H, 3.81. 1H
NMR (CDCl3): δ 8.67 (d, J = 5.7 Hz, 2H, HCN), 7.77 (d, J = 8.1
Hz, 2H, Ar-H), 7.67 (dd, J = 7.7, 12.5 Hz, 4H, Ar-H), 7.60 (t, J = 7.7
Hz, 2H, Ar-H), 7.16 (t, J = 7.4 Hz, 2H, Ar-H), 6.98 (dd, J = 6.4, 13.2
Hz, 2H, Ar-H), 2.21−2.05 (m, 4H, CH2CH2CH2), 1.81−1.69 (m,
24H, C5Me4), 1.50−1.42 (m, 2H, CH2CH2CH2). ESI-MS (m/z): 1103
([M − I]+, based on 193Ir).
Compound 7c (n = 4). Mp: >300 °C. Anal. Calcd for
C44H48I2Ir2N2: C, 42.51; H, 3.89. Found: C, 42.69; H, 3.95. 1H
NMR (CDCl3): δ 8.69 (d, J = 5.9 Hz, 2H, HCN), 7.79 (d, J = 7.9
Hz, 2H, Ar-H), 7.69 (dd, J = 7.8, 14.3 Hz, 4H, Ar-H), 7.61 (t, J = 7.9
Hz, 2H, Ar-H), 7.16 (t, J = 7.1 Hz, 2H, Ar-H), 6.98 (dd, J = 7.8, 13.9
Hz, 2H, Ar-H), 2.13−2.10 (m, 4H, CH2CH2CH2CH2), 1.80−1.74 (m,
24H, C5Me4), 1.43 (m, 4H, CH2CH2CH2CH2). ESI-MS (m/z): 1117
([M − I]+, based on 193Ir).
Preparation of Cyclometalated Dinuclear Iridium Complexs
8b,c. A solution of 3b (80.0 mg, 0.0681 mmol), N-benzylidenemethyl-
amine (19.4 mg, 0.163 mmol), and KOH (11.2 mg, 0.200 mmol) in 30
mL of CH3CN was refluxed for 24 h. After filtration through Celite the
filtrate was concentrated and further purified via neutral alumina gel
chromatography with CH2Cl2 to give a yellow solid, 8b (47 mg, 60%).
By using similar procedures, 8c could be obtained as a yellow solid in
55% yield.
Preparation of Cp*Ir(PPh3)I2. A suspension of [Cp*IrI2]2 (50
mg, 0.0426 mmol) and PPh3 (23 mg, 0.0877 mmol) in 20 mL of
CH2Cl2 was stirred for 2 h to give a red solution. After removal of
solvent in vacuo the residue was washed with hexane three times to
give a red solid (69 mg, 96%). Mp: 238 °C. Anal. Calcd for
1
C28H30I2IrP: C, 39.87; H, 3.58. Found: C, 39.93; H, 3.55. H NMR
(CDCl3): δ 7.79 (s, 2H, Ar-H), 7.60 (m, 4H, Ar-H), 7.44 (s, 6H, Ar-
H), 7.23 (s, 3H, Ar-H), 1.66 (d, J = 2.2 Hz, 15H, C5Me5). 31P NMR: δ
−8.2 (s). ESI-MS (m/z): 717 ([M − I]+, based on 193Ir).
Compound 8b (n = 3). Mp: >300 °C. Anal. Calcd for
C37H46I2Ir2N2: C, 38.41; H, 4.01. Found: C, 38.23; H, 3.89. 1H
NMR (CDCl3): δ 8.13 (s, 2H, HCN), 7.66 (d, J = 7.6 Hz, 2H,
C6H4), 7.52 (t, J = 7.3 Hz, 2H, C6H4), 7.10 (t, J = 7.4 Hz, 2H, C6H4),
6.92 (t, J = 7.3 Hz, 2H, C6H4), 3.94 (s, 6H, NMe), 2.23 (m, 4H,
CH2CH2CH2), 1.86−1.78 (m, 24H, C5Me4), 1.53 (m, 2H,
CH2CH2CH2). ESI-MS (m/z): 1031 ([M − I]+, based on 193Ir).
Compound 8c (n = 4). Mp: >300 °C. Anal. Calcd for
C38H48I2Ir2N2: C, 38.97; H, 4.13. Found: C, 38.93; H, 4.12. 1H
NMR (CDCl3): δ 8.13 (s, 2H, HCN), 7.68 (d, J = 7.6 Hz, 2H,
C6H4), 7.52 (t, J = 7.5 Hz, 2H, C6H4), 7.10 (t, J = 7.4 Hz, 2H, C6H4),
6.92 (t, J = 7.3 Hz, 2H, C6H4), 3.94 (s, 6H, NMe), 2.18 (m, 4H,
CH2CH2CH2CH2), 1.88−1.82 (m, 24H, C5Me4), 1.45 (m, 4H,
CH2CH2CH2CH2). ESI-MS (m/z): 1045 ([M − I]+, based on 193Ir).
Preparation of Cyclometalated Dinuclear Iridium Complexs
9b,c. A solution of 3b (80.0 mg, 0.0681 mmol), (E)-2-styrylpyridine
(29.5 mg, 0.163 mmol), and KOH (11.2 mg, 0.200 mmol) in 30 mL of
CH3CN was refluxed for 24 h. After filtration through Celite the
filtrate was concentrated and further purified via neutral alumina gel
chromatography with CH2Cl2/acetone (20:1) to give a yellow solid,
9b (44 mg, 50%). By using similar procedures, 9c could be obtained as
a yellow solid in 53% yield.
General Procedure for Iridium-Catalyzed Selective Amine
Cross-Coupling Reaction. Catalyst (2 mol % Ir), amine substrate
RNH2 (1 mmol), diisopropylamine (3 mmol), and xylene (2 mL) was
added to a Schlenk tube. The mixture was heated under reflux for 10 h
and then cooled to room temperature. The resulting solution was
directly purified by column chromatography with petroleum ether/
ethyl acetate (4:1) as eluent. The structures of products 11 and 12,6g
13,15 14−18,6g 19,16 and 206g were confirmed by comparing their H
1
NMR spectra with those in the literature.
Crystallographic Studies. Single crystals of 2a, 4a, 5b, and 7b
suitable for X-ray diffraction analysis were grown from a hexane/
CH2Cl2 solution at room temperature, while 6c was grown from a
hexane/ether solution. Data collection was performed on a Rigaku
Saturn 70 diffractometer equipped with a rotating anode system by
using graphite-monochromated Mo Kα radiation (ω−2θ scans).
Semiempirical absorption corrections were applied for all complexes.
The structures were solved by direct methods and refined by full-
matrix least-squares. All calculations were carried out using the
SHELXL-97 program system. All non-hydrogen atoms were refined
anisotropically. Hydrogen atoms were assigned idealized positions and
were included in structure factor calculations. The crystal data and
summary of X-ray data collection for complexes 2a, 4a, 5b, 6c, and 7b
are presented in the Supporting Information. In 7b, the phenyl
pyridine and iodine groups attached to one of the iridium atoms are
disordered.
Compound 9b (n = 3). Mp: >300 °C. Anal. Calcd for
C47H50I2Ir2N2: C, 44.06; H, 3.93. Found: C, 44.18; H, 3.90. 1H
NMR (CDCl3): δ 8.47 (d, J = 5.7 Hz, 2H, HCN), 7.57 (d, J = 7.5
Hz, 2H, Ar-H), 7.38 (t, J = 8.3 Hz, 2H, Ar-H), 7.29−7.21 (m, J = 8H,
Ar-H), 6.94 (s, 2H, Ar-H), 6.71 (t, J = 5.9 Hz, 2H, Ar-H), 1.87 (t, J =
7.9 Hz, 4H, CH2CH2CH2), 1.58−1.49 (m, 24H, C5Me4), 1.26 (m, 2H,
CH2CH2CH2). ESI-MS (m/z): 1155 ([M − I]+, based on 193Ir).
3259
dx.doi.org/10.1021/om4001742 | Organometallics 2013, 32, 3253−3261

Organometallics
Article
Organometallics 2008, 27, 1247. (s) Yuan, J.; Hughes, R. P.; Rheingold,
A. L. Organometallics 2011, 10, 1744.
(4) For examples of Cp*Ir complexes used in organometallic
ASSOCIATED CONTENT
* Supporting Information
A CIF file giving X-ray structural information for 2a, 4a, 5b, 6c,
and 7b. This material is available free of charge via the Internet
at http://pubs.acs.org.
■
S
chemistry, see: (a) Bauer, W.; Prem, M.; Polborn, K.; Sunkel, K.;
̈
Steglich, W.; Beck, W. Eur. J. Inorg. Chem. 1998, 485. (b) Davies, D. L.;
Al-Duaij, O.; Fawcett, J.; Giardiello, M.; Hilton, S. T.; Russell, D. R.
Dalton Trans. 2003, 4132. (c) Corberan
Chem. Soc. 2006, 128, 3974. (d) Scheeren, C.; Maasarani, F.; Hijazi, A.;
Djukic, J.-P.; Pfeffer, M. Organometallics 2007, 26, 3336. (e) Corberan
́
́
, R.; Sanau, M.; Peris, E. J. Am.
AUTHOR INFORMATION
Corresponding Author
*Tel and fax: +86-22-23504781. E-mail: bqwang@nankai.edu.
■
́
,
R.; Lillo, V.; Mata, J. A.; Fernandez, E.; Peris, E. Organometallics 2007,
26, 4350. (f) Arita, S.; Koike, T.; Kayaki, Y.; Ikariya, T. Organometallics
2008, 27, 2795. (g) Li, L.; Brennessel, W. W.; Jones, W. D. J. Am.
Chem. Soc. 2008, 130, 12414. (h) Boutadla, Y.; Davies, D. L.; Jones, R.
C.; Singh, K. Chem.Eur. J. 2011, 17, 3438. (i) Broeckx, L. E. E.; Lutz,
cn.
Notes
The authors declare no competing financial interest.
M.; Vogt, D.; Muller, C. Chem. Commun. 2011, 2003. (j) Newman, L.
̈
ACKNOWLEDGMENTS
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(q) Grotjahn, D. B.; Kraus, J. E.; Amouri, H.; Rager, M.-N.; Cooksy, A.
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■
We are grateful to the National Natural Science Foundation of
China (Nos. 21072101, 21174068, 21072097, and 21121002)
and the Research Fund for the Doctoral Program of Higher
Education of China (No. 20110031110009) for financial
support.
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