Mild oxidative addition of C-H bonds to a hydrido-bridged dinuclear complex of iridium(II) induced by the coordination of heteroatomic ligands

Article abstract of DOI:10.1002/ejic.200800469

The oxidative addition of C-H bonds to a dinuclear complex of divalent iridium, [Cp*Ir(μ-H)]₂ (1), has been investigated. Reactions of 1 with phosphorus compounds containing a phenyl ring (PR¹R ²Ph) at ambient temperature gave novel five-membered diiridacyclic [(Cp*IrH)₂(μ-H)(μ-R¹R²PC ₆H₄)] [R¹ = R² = Me (2a); R ¹ = Me, R² = Ph (2b); R¹ = R² = Ph (2c); R¹ = R² = OEt (2d); and R¹ = OEt, R ² = Ph (2e)] complexes through ortho-C-H activation of the phenyl ring bound to the phosphorus atom. The reaction of 1 with tripropylphosphane gave a new four-membered diiridacyclic [(Cp*IrH)₂(μ-H)(μ- Pr₂PCHCH₂CH₃)] (3) complex in a similar manner. On the other hand, the reaction of 1 with triethyl phosphite gave a Cp*-metalated product, [Ir(H)(P(OEt)₃)(μ,η⁵, η¹-C₅Me₄CH₂)-(μ-H)Ir(H) (Cp*)] (4), through C-H activation of a methyl group on one of the Cp* ligands. Furthermore, similar mild C-H activation reactions of 1 with sulfoxides have also been revealed. Thus, reactions of 1 with dimethyl sulfoxide and a couple of sulfoxides containing phenyl groups brought about the activation of the C-H bonds of a methyl group and a phenyl group to give [(Cp*IrH) ₂(μ-H)(μ-MeS(=O)CH₂)] (5) and [(Cp*IrH) ₂(μ-H)(μ-RS(=O)C₆H₄)] [R = Me (6a) and R = Ph (6b)], respectively. The structures of 2a, 4, 5, and 6a have been confirmed by X-ray analysis. A plausible reaction pathway for these C-H activation reactions has been proposed. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.

Full text of DOI:10.1002/ejic.200800469

FULL PAPER
DOI: 10.1002/ejic.200800469
Mild Oxidative Addition of C–H Bonds to a Hydrido-Bridged Dinuclear
Complex of Iridium(II) Induced by the Coordination of Heteroatomic Ligands
Yoshinori Takahashi,[a] Ken-ichi Fujita,*[a,b] and Ryohei Yamaguchi*[a]
Keywords: Cooperative effects / Iridium / C–H activation / P ligands / S ligands
The oxidative addition of C–H bonds to a dinuclear complex
of divalent iridium, [Cp*Ir(µ-H)]2 (1), has been investigated.
Reactions of 1 with phosphorus compounds containing a
phenyl ring (PR1R2Ph) at ambient temperature gave novel
five-membered diiridacyclic [(Cp*IrH)2(µ-H)(µ-R1R2PC6H4)]
[R1 = R2 = Me (2a); R1 = Me, R2 = Ph (2b); R1 = R2 = Ph (2c);
R1 = R2 = OEt (2d); and R1 = OEt, R2 = Ph (2e)] complexes
through ortho-C–H activation of the phenyl ring bound to the
phosphorus atom. The reaction of 1 with tripropylphosphane
gave a new four-membered diiridacyclic [(Cp*IrH)2(µ-H)(µ-
Pr2PCHCH2CH3)] (3) complex in a similar manner. On the
other hand, the reaction of 1 with triethyl phosphite gave a
Cp*-metalated product, [Ir(H)(P(OEt)3)(µ,η5,η1-C5Me4CH2)-
(µ-H)Ir(H)(Cp*)] (4), through C–H activation of a methyl
group on one of the Cp* ligands. Furthermore, similar mild
C–H activation reactions of 1 with sulfoxides have also been
revealed. Thus, reactions of 1 with dimethyl sulfoxide and a
couple of sulfoxides containing phenyl groups brought about
the activation of the C–H bonds of a methyl group and a
phenyl group to give [(Cp*IrH)2(µ-H)(µ-MeS(=O)CH2)] (5)
and [(Cp*IrH)2(µ-H)(µ-RS(=O)C6H4)] [R = Me (6a) and R = Ph
(6b)], respectively. The structures of 2a, 4, 5, and 6a have
been confirmed by X-ray analysis. A plausible reaction path-
way for these C–H activation reactions has been proposed.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2008)
sequent transformation of inert and abundant hydrocarbon
molecules is an ideal synthetic tool from the viewpoint of
efficiency and economy.
Introduction
Recently, much attention has been paid to bond cleavage
reactions on multimetallic complexes because these are ex-
pected to outperform monometallic complexes.[1] The prox-
imity of multiple metal centers can generate unique func-
tions based on their cooperativity.[2,3] To date, several inter-
esting reports on the cooperative reactivity of multimetallic
complexes bridged by carbonyls or hydrides have appeared.
For example, Ru3(CO)12 and Os3(CO)12 exhibited high
capabilities for the bond activation reactions of organic
molecules.[4] The bond cleavage and reconstruction of small
organic molecules on polyhydrido ruthenium clusters have
also been reported.[5] While a number of bond activation
processes on transition metal clusters including ortho metal-
lation have been reported, the activation of carbon–hydro-
gen (C–H) bonds in organic molecules by transition metal
complexes is still one of the most attractive areas of study
in organometallic chemistry[6] since the activation and sub-
Scheme 1.
We previously reported on the synthesis and reactivity of
diphosphane- and dihydrido-bridged diiridium(III) com-
plexes[7] and disclosed the capability of the diiridium com-
plexes to conduct facile C–H activation.[7c] We have found
that treatment of a dihydrido-bridged complex of divalent
iridium(II), [Cp*Ir(µ-H)]2 (Cp* = η5-C5Me5) (1), with mon-
ophosphane brings about smooth C–H bond activation at
the ortho position of the phenyl ring bound to the phospho-
rus atom at ambient temperature. It should be noted that
in this reaction the phosphorus atom is coordinated to one
of the iridium centers, while the C–H activation occurs on
the other iridium center, which suggests that coordination
of the ligand to the metal center might lead to enhancement
of the reactivity of the adjacent metal center towards oxi-
dative addition. Thus, it would be provable that coordina-
tion of a donor ligand to one of the metal centers gives rise
to electron transfer to the other metal center to afford a
mixed-valent intermediate and induce the facile oxidative
[a] Graduate School of Human and Environmental Studies, Kyoto
University,
Sakyo-ku, Kyoto 606-8501, Japan
Fax: +81-75-753-6634
E-mail: yama@kagaku.mbox.media.kyoto-u.ac.jp
[b] Graduate School of Global Environmental Studies, Kyoto Uni-
versity,
Sakyo-ku, Kyoto 606-8501, Japan
Fax: +81-75-753-6634
E-mail: fujitak@kagaku.mbox.media.kyoto-u.ac.jp
4360
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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Addition of C–H Bonds to a Dinuclear IrII Complex
addition of C–H bonds on the lower valent metal center trast to these reports, it is noteworthy that selective C–H
(Scheme 1). Herein, we report the mild C–H bond acti- bond activation has occurred in the present study, and no
vation on the diiridium core in 1 induced by the coordina- P–C cleavage has been observed.
tion of a series of phosphorus compounds and sulfoxides.
Results and Discussion
Reactions of 1 with Phosphorus Ligands: Oxidative
Addition of the C–H Bond of Phosphorus Ligands
(1)
The reaction of a slight excess (1.1 equiv.) of dimeth-
yl(phenyl)phosphane with 1 in benzene at room tempera-
ture for 16 h afforded a new complex, 2a, quantitatively
(98% isolated yield). The complex 2a was formed by coor-
dination of the phosphorus atom to one of the iridium cen-
ters and C–H activation of the ortho position of the phenyl
ring on the other iridium center [Equation (1)]. The κ-P,C
bridging structure of 2a was determined by NMR spec-
troscopy, elemental analysis, and X-ray crystallography. In
the 1H NMR of 2a at room temperature, two nonequivalent
signals due to the two Cp* ligands were observed at δ =
1.92 and 1.90 ppm. Three hydrides were observed at δ =
–17.71 ppm as a broad singlet at room temperature, which
indicates rapid interchange of the three hydrides on the
NMR time scale because the signals due to the hydrides
split into a singlet (δ = –14.87 ppm) and two doublets [δ =
–17.73 (JPH = 32 Hz) and –20.88 (JPH = 10 Hz) ppm] at
–90 °C. The singlet resonance would be due to a terminal
hydride bound to the iridium without the phosphorus li-
gand. The doublet resonance with the larger JPH would be
Figure 1. ORTEP drawing of complex 2a with 50% thermal prob-
due to a terminal hydride bound to the iridium coordinated
by a phosphorus ligand, and the doublet resonance with
ability ellipsoids. Hydrogen atoms are omitted for clarity. Selected
bond lengths [Å] and angles [°]: Ir(1)–Ir(2) 2.9782(4), Ir(1)–P(1)
the smaller JPH would be due to a bridging hydride. In the
2.214(2), Ir(2)–C(21) 2.052(8), Ir(2)–Ir(1)–P(1) 76.83(5), Ir(1)–
13C{1H} NMR, a signal due to the aromatic carbon bound
Ir(2)–C(21) 84.7(2).
to iridium was observed at δ = 150.5 ppm as a doublet (2JPC
= 30 Hz). A signal due to the carbon bound to phosphorus
was observed at δ = 160.8 ppm as a doublet with a large
Next, we investigated the C–H activation process with a
coupling constant (1JPC = 76 Hz).[8] Finally, an X-ray dif- series of phosphorus ligands containing phenyl rings. The
fraction study of 2a confirmed its structure. The molecular results are summarized in Equation (1). The structures of
geometry and atom-numbering system are shown in Fig- complexes 2b–2e were determined by NMR spectroscopy
ure 1. It is apparent that the two iridium centers are bridged and elemental analysis, and these provided support for the
by an Me2PC6H4 moiety in a κ-P,C fashion. The iridium– κ-P,C bridging structures. These reactions proceeded almost
iridium distance is 2.9782(4) Å, which is the standard length quantitatively, however the isolated yields were moderate in
for monohydrido-bridged diiridium complexes.[9,10] Al- some cases because of the instability of the products. The
though the positions of the three hydrides could not be de- reaction of 1 with triphenylphosphane (cone angle = 145°)
[15]
termined from Fourier difference maps, the transoid config-
was obviously much slower than the reactions with less
uration of the two Cp* ligands strongly suggests that two sterically hindered dimethyl(phenyl)phosphane (cone angle
of the three hydrides are located at the terminal positions = 122°) and diethyl phenylphosphonite (cone angle = 116°),
and another one at the bridging position,[9] consistent with which indicates that the reaction rate is dependent on the
1
the observation in the H NMR analysis at –90 °C. There steric bulkiness of the phosphorus ligands rather than their
have been a few reports on the reactions of hydrido-bridged electronic nature.[16]
dinuclear complexes, [(Cp*Ru)(µ-H)2]2,[11] [(C6Me6Ru)2(µ-
Then, we turned our attention to the reaction with phos-
H)3]+,[12] [Cp*Ir(µ-H)Cl]2,[13] and [Cp*Ir(µ-H)3RuCp*],[14] phorus compounds containing no aromatic rings. The reac-
with phosphorus ligands, in which P–C bond activation tion of 1 with tripropylphosphane resulted in C–H acti-
took place to give phosphide-bridged complexes. In con- vation of the α-methylene group on the phosphorus atom
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Y. Takahashi, K.-i. Fujita, R. Yamaguchi
FULL PAPER
to give the four-membered κ-P,C bridging complex, 3
[Equation (2)]. Characterization of 3 was carried out by
NMR spectroscopy, and the yield was determined by NMR
1
because of difficulties in isolating 3. In the H NMR of 3,
two nonequivalent signals due to the two Cp* ligands were
observed at δ = 2.06 and 1.98 ppm, and broad signals due
to the three hydrides were observed at δ = –16.77, –17.56,
and –22.08 ppm. Three triplets due to the methyl protons
of the propyl groups were observed at δ = 1.24, 1.05, and
1.00 ppm. A signal due to the methine proton was observed
at δ = 1.41 ppm overlapped with signals due to the methyl-
ene protons. In the 13C{1H} NMR, a characteristic signal
for the methine carbon bound to iridium was observed at δ
= –19.0 ppm as a doublet (J = 18 Hz). A correlation be-
tween the methine carbon (δ = –19.0 ppm) and the methine
proton (δ = 1.41 ppm) was confirmed in a 13C{1H}–1H
COSY spectrum. All NMR spectroscopic data (1H,
13C{1H}, and 31P{1H}) of 3 were consistent with the pro-
posed structure.
Figure 2. ORTEP drawing of complex 4 with 50% thermal prob-
ability ellipsoids. Hydrogen atoms are omitted for clarity. Selected
bond lengths [Å] and angles [°]: Ir(1)–Ir(2) 2.9315(19), Ir(1)–P(1)
2.179(7), Ir(2)–C(10) 2.14(2), Ir(2)–Ir(1)–P(1) 113.5(7), Ir(1)–Ir(2)–
C(1) 76.2(10).
Reactions of 1 with Sulfoxides: Oxidative Addition of the
C–H Bond of Sulfoxides
The results shown above prompted us to investigate the
activation of other donor molecules, and we found that one
of the methyl groups of dimethyl sulfoxide was subject to
oxidative addition of a C–H bond on ligation to 1. Thus,
dimethyl sulfoxide reacted with 1 in benzene at room tem-
perature for 64 h to induce the C–H activation of one of
the methyl groups on the sulfur atom to give 5 in 69% yield
[Equation (4)]. Complex 5 was characterized by NMR spec-
troscopy and X-ray crystallography. Since the NMR spectra
of 5 showed broad, unresolved resonances at room tem-
perature, they were measured at –80 °C. In the 1H NMR of
5, three nonequivalent hydrides were observed at δ =
–13.38, –17.24, and –20.68 ppm together with signals for
the two Cp* ligands (δ = 1.98 and 1.87 ppm). A signal due
to the methyl groups of dimethyl sulfoxide was observed at
δ = 3.12 ppm, and two nonequivalent signals due to the
protons of the methylene group bound to iridium were ob-
served at δ = 4.61 and 2.56 ppm. In the 13C{1H} NMR
spectrum, a signal due to the methylene carbon was ob-
served at δ = 12.0 ppm, and a signal for the methyl carbon
on the sulfur atom was observed at δ = 42.9 ppm, which
was slightly shifted to a lower field than that for free di-
methyl sulfoxide (δ = 40.2 ppm in CD2Cl2 at –80 °C). Single
crystals suitable for X-ray crystallography were obtained by
recrystallization from hexane solution. The results of the X-
ray diffraction study of 5 are shown in Figure 3. It is appar-
ent that the complex contains a four-membered ring con-
sisting of the two iridium atoms, the sulfur atom, and the
carbon atom of the methylene group. The length of the irid-
ium–carbon bond is 2.112(9) Å, which is the standard
length for an iridium–sp3 carbon bond.[17] No interaction is
observed between the oxygen atom and the iridium centers.
We further examined the C–H activation reactions of
other sulfoxides such as methyl phenyl sulfoxide and di-
phenyl sulfoxide [Equation (5)]. In the reaction of 1 with
methyl phenyl sulfoxide, selective C–H activation at the or-
(3) tho position of the phenyl ring occurred to give 6a. Com-
(2)
On the other hand, the reaction of 1 with triethyl phos-
phite brought about the C–H activation of a methyl group
on one of the Cp* ligands to give rise to 4 [Equation (3)].
The structure of 4 was determined by NMR spectroscopy
1
and X-ray crystallography. In the H NMR of 4, a signal
due to one of the Cp* ligands was observed at δ = 2.08 ppm
with an integration value of 15 H as well as signals due to
the four methyl groups on the activated Cp* ligand at δ =
2.15, 1.89, 1.67, and 1.37 ppm (an integration value of 3 H
was assigned to each of the signals). Signals due to the pro-
tons of the methylene group bound to iridium were found
at δ = 3.33 and 2.75 ppm. In the 13C{1H} NMR, a charac-
teristic signal due to the methylene carbon was observed at
δ = –25.3 ppm as a singlet. The structure of 4 was unequiv-
ocally confirmed by an X-ray diffraction study. The molecu-
lar geometry and atom-numbering system are shown in Fig-
ure 2. It is clear that the phosphorus atom binds to one of
the iridium centers and that a methyl groups on one of the
Cp* ligands is activated by the other iridium center.
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Eur. J. Inorg. Chem. 2008, 4360–4368

Addition of C–H Bonds to a Dinuclear IrII Complex
(4)
Figure 4. ORTEP drawing of complex 6a with 50% thermal prob-
ability ellipsoids. Hydrogen atoms are omitted for clarity. Selected
bond lengths [Å] and angles [°]: Ir(1)–Ir(2) 2.9836(2), Ir(1)–S(1)
2.2034(15), Ir(2)–C(21) 2.055(5), S(1)–C(22) 1.790(6), S(1)–O(1)
1.485(4), Ir(2)–Ir(1)–S(1) 80.08(3), Ir(1)–Ir(2)–C(21) 83.98(13).
Figure 3. ORTEP drawing of complex 5 with 50% thermal prob-
ability ellipsoids. Hydrogen atoms are omitted for clarity. Selected
bond lengths [Å] and angles [°]: Ir(1)–Ir(2) 2.9414(4), Ir(1)–S(1)
2.2097(19), Ir(2)–C(21) 2.112(9), S(1)–C(21) 1.739(10), S(1)–C(22)
1.797(9), S(1)–O(1) 1.485(6), Ir(2)–Ir(1)–S(1) 71.26(5), Ir(1)–Ir(2)–
C(21) 74.0(2).
Mechanistic Considerations
Two plausible pathways for the present oxidative ad-
dition of C–H bonds induced by coordination of a heteroat-
omic ligand to dinuclear complex 1 are shown in Scheme 2.
plex 6a was characterized by NMR spectroscopy and X-ray At first, we considered that direct oxidative addition of a
1
structural analysis. In the H NMR spectrum of 6a, two C–H bond to 1 to produce A followed by coordination of
nonequivalent signals due to the two Cp* ligands (δ = 1.88 the heteroatom could occur to give stable product 2 (path
and 1.81 ppm) and broad signals due to hydrides [δ = a), because H/D scrambling reactions of the hydrides in 1-
–15.27 (2 H) and –19.57 (1 H) ppm] were observed. In the d2 with dihydrogen or methanol have been previously re-
13C{1H} NMR spectrum, a signal for the aromatic carbon ported by Hou et al.[19] Another plausible pathway starts
bound to an iridium center was observed at δ = 144.2 ppm. with initial coordination of the heteroatom to one of the
The results of the X-ray diffraction study of 6a are shown iridium centers (IrII–IrII) to afford B, which could be trans-
in Figure 4. The crystal structure of 6a is very similar to formed to a mixed-valent (IrIII–IrI) intermediate C by elec-
that of 2a derived from dimethyl(phenyl)phosphane with re- tron transfer between the two iridium centers with concomi-
spect to the iridium–iridium distance [2.9836(2) Å in 6a vs. tant migration of a bridging hydride into a terminal posi-
2.9782(4) Å in 2a], the iridium–sulfur distance tion. The successive oxidative addition of a C–H bond to
[2.2034(15) Å in 6a vs. an iridium–phosphorus distance of the highly reactive IrI center should then occur very
2.214(2) Å in 2a], and the iridium–carbon distance smoothly to give product 2 (path b).
[2.055(5) Å in 6a vs. 2.052(8) Å in 2a]. The ortho C–H acti-
To examine the possibility of path a, an H/D scrambling
vation of the phenyl ring of diphenyl sulfoxide with 1 also experiment of 1 with C6D6 was attempted; however, no de-
proceeded to give 6b [Equation (5)]. The structure of 6b was tectable H/D scrambling of the hydrides and the Cp*
characterized by NMR spectroscopy and elemental analy- methyl protons was observed (e.g., complex 1 remained un-
sis. Thus, it has been found that not only phosphorus com- changed), which suggests that the direct oxidative addition
pounds, but also sulfoxides, are coordinating molecules that of a C–H bond to 1 to produce A (path a) is improbable.
can be effectively subjected to the oxidative addition of C– Additionally, the reaction of 1 with triethyl phosphite to
H bonds to the dinuclear complex of divalent iridium, 1.[18] afford 4 through the C–H activation of a Cp* methyl group
strongly supports a pathway whereby coordination of do-
nor molecules to one of the iridium centers induces the acti-
vation of the adjacent metal center for the subsequent oxi-
dative addition. Thus, we propose that the present oxidative
addition reactions of C–H bonds proceed through pathway
b, and that the reactivity of 1 in the C–H activation reac-
tions with donor ligands can be attributed to the co-
operative reactivity of the dinuclear complex of divalent
(5) iridium, 1.
Eur. J. Inorg. Chem. 2008, 4360–4368
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Y. Takahashi, K.-i. Fujita, R. Yamaguchi
FULL PAPER
the Microanalysis Center of Kyoto University. 1H, 13C{1H}, and
31P{1H} NMR spectra were measured with JEOL EX-270 and
JEOL A-500 spectrometers. 31P{1H} NMR spectra were referenced
to an 85% H3PO4 external standard. Solvents were dried by using
standard procedures and distilled prior to use. [Cp*Ir(µ-H)]2 (1)
[19]
and P(OEt)2Ph[20] were prepared by literature methods. Other
reagents were used as obtained from commercial sources.
Reaction of [Cp*Ir(µ-H)]2 (1) with PMe2Ph To Give 2a: A two-
necked 30 mL flask was charged with 1 (157 mg, 0.239 mmol) in
benzene
(0.7 mL).
Dimethyl(phenyl)phosphane
(36.1 mg,
0.261 mmol) was added to the reaction mixture, and this was stirred
at room temperature for 16 h. After removal of the volatiles in
vacuo, the residue was extracted with hexane. Evaporation of the
solvent gave 2a as a yellow-brown powder (185 mg, 0.233 mmol,
98%). Single crystals suitable for X-ray analysis were obtained by
1
cooling of a hexane solution of 2a. H NMR (500.00 MHz, C6D6,
r.t.): δ = 7.97–7.95 (m, 1 H, aromatic), 7.03 (t, J = 8 Hz, 1 H,
aromatic), 6.97 (t, J = 8 Hz, 1 H, aromatic), 6.75–6.71 (m, 1 H,
aromatic), 1.92 (s, 15 H, Cp*), 1.90 (s, 15 H, Cp*), 1.65 (d, J =
10 Hz, 6 H, PMe), –17.71 (br. s, 3 H, Ir-H) ppm. 1H NMR
(500.00 MHz, CD2Cl2, –90 °C): δ = 7.37 (d, J = 6 Hz, 1 H, aro-
matic), 6.63 (m, 2 H, aromatic), 6.53 (m, 1 H, aromatic), 1.88 (s,
15 H, Cp*), 1.81 (s, 15 H, Cp*), 1.59 (d, J = 9 Hz, 3 H, PMe), 1.46
(d, J = 10 Hz, 3 H, PMe), –14.87 (s, 1 H, terminal Ir-H), –17.73
(d, J = 32 Hz, 1 H, terminal Ir-H), –20.88 (d, J = 10 Hz, 1 H,
bridging Ir-H-Ir) ppm. 13C{1H} NMR (125.65 MHz, C6D6, r.t.): δ
= 160.8 (d, J = 76 Hz, P-C), 150.5 (d, J = 30 Hz, Ir-C), 143.3 (d,
J = 19 Hz, aromatic), 126.8 (d, J = 3 Hz, aromatic), 126.6 (d, J =
10 Hz, aromatic), 119.5 (d, J = 9 Hz, aromatic), 93.3 (d, J = 3 Hz,
C5Me5), 89.6 (s, C5Me5), 22.7 (d, J = 28 Hz, PMe), 11.4 (s, C5Me5),
10.7 (s, C5Me5) ppm. 31P{1H} NMR (202.35 MHz, C6D6, r.t.): δ =
–46.8 (s) ppm. M.p. 137 °C (dec.). C28H43Ir2P (795.05): calcd. C
42.30, H 5.45; found C 42.34, H 5.39.
Scheme 2. Plausible reaction pathways for the oxidative addition of
a C–H bond to 1 induced by the coordination of a phosphorus
ligand.
Reaction of 1 with Other Phosphorus Ligands To Give 2b–2e, 3, and
4: These reactions were carried out in a similar manner as described
above.
A similar reaction of 1 (104 mg, 0.158 mmol) with methyldi-
phenylphosphane (35.9 mg, 0.179 mmol) gave 2b as a brown pow-
der (113 mg, 0.132 mmol, 84%). 1H NMR (500.00 MHz, C6D6,
r.t.): δ = 8.04 (d, J = 7 Hz, 1 H, aromatic), 7.53–7.50 (m, 2 H,
aromatic), 7.10 (t, J = 8 Hz, 1 H, aromatic), 7.06–7.04 (m, 3 H,
aromatic), 6.97 (t, J = 8 Hz, 1 H, aromatic), 6.85 (t, J = 8 Hz, 1
H, aromatic), 1.92 (s, 15 H, Cp*), 1.68 (s, 15 H, Cp*), 1.63 (d, J =
9 Hz, 3 H, PMe), –17.33 (br. s, 3 H, Ir-H) ppm. 1H NMR
(500.00 MHz, CD2Cl2, –90 °C): δ = 7.48 (m, 2 H, aromatic), 7.16
(m, 2 H, aromatic), 7.09 (m, 2 H, aromatic), 6.74 (m, 2 H, aro-
matic), 6.63 (m, 1 H, aromatic), 2.04 (s, 15 H, Cp*), 1.59 (d, J =
9 Hz, 3 H, PMe), 1.46 (s, 15 H, Cp*), –15.24 (s, 1 H, Ir-H), –17.39
(d, J = 32 Hz, 1 H, Ir-H), –18.98 (d, J = 6 Hz, 1 H, Ir-H-Ir) ppm.
13C{1H} NMR (125.65 MHz, C6D6, r.t.): δ = 158.3 (d, J = 80 Hz,
P-C), 153.3 (d, J = 31 Hz, Ir-C), 145.2 (d, J = 59 Hz, aromatic),
143.6 (d, J = 19 Hz, aromatic), 131.2 (d, J = 10 Hz, aromatic),
129.3 (d, J = 10 Hz, aromatic), 128.8 (d, J = 2 Hz, aromatic), 127.6
(d, J = 10 Hz, aromatic), 127.4 (d, J = 2 Hz, aromatic), 119.7 (d,
J = 9 Hz, aromatic), 93.6 (d, J = 3 Hz, C5Me5), 89.9 (s, C5Me5),
21.0 (d, J = 31 Hz, PMe), 11.3 (s, C5Me5), 10.2 (s, C5Me5) ppm.
31P{1H} NMR (202.35 MHz, C6D6, r.t.): δ = –25.1 (s) ppm. M.p.
50.0–51.4 °C. C33H45Ir2P (857.12): calcd. C 46.24, H 5.29; found C
46.20, H 5.31.
Conclusions
We have disclosed that mild oxidative additions of C–H
bonds in phosphorus, Cp*, and sulfoxide ligands take place
at ambient temperature by reaction with the dinuclear irid-
ium complex, 1. Heteroatomic ligands containing phenyl
rings or α-C–H bonds to the heteroatom resulted in the C–
H activation of the ortho-C–H bond or the α-C–H bond,
while heteroatomic ligands containing neither phenyl ring
nor α-C–H bond led to the C–H activation of a Cp* ligand.
These C–H bond activation reactions are induced by coor-
dination of heteroatomic ligands, such as phosphorus com-
pounds and sulfoxides, to produce novel κ-P,C and κ-S,C
bridging complexes. The proximity of the two iridium cen-
ters together with the characteristic electron configuration
(IrII–IrII) of 1 provides these simple but unique reactivities
based on synergetic and cooperative effects.
Experimental Section
General Procedures: All manipulations were performed under a dry
argon atmosphere with standard Schlenk techniques or in an N2
dry-box. Melting points were determined on a Yanagimoto micro
melting point apparatus. Elemental analyses were carried out at
A similar reaction of 1 (61.4 mg, 0.0935 mmol) with triphenylphos-
phane (27.6 mg, 0.105 mmol) gave 2c as an orange powder (44 mg,
1
0.047 mmol, 51%). H NMR (500.00 MHz, C6D6, r.t.): δ = 8.10–
4364
www.eurjic.org
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2008, 4360–4368

Addition of C–H Bonds to a Dinuclear IrII Complex
8.08 (m, 1 H, aromatic), 7.53–7.50 (m, 4 H, aromatic), 7.08 (m, 4
δ = 70.5 (s) ppm. M.p. 145 °C (dec.). C34H47Ir2O2P (887.14): calcd.
H, aromatic), 7.02–6.99 (m, 2 H, aromatic), 6.98–6.95 (m, 1 H, C 46.03, H 5.34; found C 45.79, H 5.32.
aromatic), 6.83–6.80 (m, 1 H, aromatic), 6.78–6.75 (m, 1 H, aro-
A similar reaction of 1 (105 mg, 0.160 mmol) with tripropylphos-
matic), 1.73 (s, 15 H, Cp*), 1.68 (d, J = 3 Hz, 15 H, Cp*), –16.29
(br., 3 H, Ir-H) ppm. H NMR (500.00 MHz, CD2Cl2, –90 °C): δ
phane (28.4 mg, 0.177 mmol) gave 3 as a brown oil (85%, deter-
mined by 31P{1H} NMR). 1H NMR (500.00 MHz, C6D6, r.t.): δ
= 2.06 (s, 15 H, Cp*), 1.98 (s, 15 H, Cp*), 1.66–1.41 (m, PCH2,
CHCH2CH3, and Ir-CH), 1.24 (t, J = 7 Hz, 3 H, CH2CH3), 1.05
(t, J = 7 Hz, 3 H, CH2CH3), 1.00 (t, J = 7 Hz, 3 H, CH2CH3),
–16.77 (br. s, 1 H, Ir-H), –17.56 (br. s, 1 H, Ir-H), –22.08 (br. s, 1
1
= 7.59–7.17 (m, 10 H, aromatic), 6.79 (br., 1 H, aromatic), 6.66 (m,
1 H, aromatic), 6.59 (m, 1 H, aromatic), 6.36 (m, 1 H, aromatic),
1.65 (s, 15 H, Cp*), 1.46 (s, 15 H, Cp*), –15.26 (s, 1 H, Ir-H),
–17.25 (d, J = 29 Hz, 1 H, Ir-H), –18.16 (br., 1 H, Ir-H) ppm.
13C{1H} NMR (125.65 MHz, C6D6, r.t.): δ = 156.9 (d, J = 83 Hz,
P-C), 152.8 (d, J = 34 Hz, Ir-C), 144.8 (d, J = 18 Hz, aromatic),
141.1 (d, J = 50 Hz, P-C), 134.2 (d, J = 20 Hz, aromatic), 134.0
(d, J = 10 Hz, aromatic), 133.9 (d, J = 10 Hz, aromatic), 128.8 (s,
aromatic), 127.4 (d, J = 9 Hz, aromatic), 119.6 (d, J = 8 Hz, aro-
matic), 93.2 (d, J = 3 Hz, C5Me5), 90.9 (s, C5Me5), 10.9 (s, C5Me5),
10.5 (s, C5Me5) ppm. 31P{1H} NMR (202.35 MHz, C6D6, r.t.): δ =
4.9 (s) ppm. M.p. 148 °C (dec.). C38H47Ir2P (919.19): calcd. C
49.65, H 5.15; found C 49.50, H 5.21.
1
H, Ir-H) ppm. H NMR (500.00 MHz, CD2Cl2, –10 °C): δ = 2.04
(s, 15 H, Cp*), 1.87 (s, 15 H, Cp*), 1.49–1.18 (m, PCH2,
CHCH2CH3, and Ir-CH), 0.95 (m, 6 H, CH2CH3), 0.82 (t, J =
7 Hz, 3 H, CH2CH3), –17.23 (s, 1 H, terminal Ir-H), –17.66 (d, J
= 28 Hz, 1 H, terminal Ir-H), –22.42 (d, J = 13 Hz, 1 H, bridging
Ir-H-Ir) ppm. 13C{1H} NMR (125.65 MHz, C6D6, r.t.): δ = 92.1
(d, J = 3 Hz, C5Me5), 88.3 (s, C5Me5), 36.3 (d, J = 34 Hz, CH2),
33.3 (s, CH2), 29.0 (d, J = 10 Hz, CH2), 19.1 (s, CH2), 18.8 (d, J =
15 Hz, Me), 18.2 (d, J = 3 Hz, CH2), 16.0 (d, J = 3 Hz, Me), 15.9
(s, Me), 11.7 (s, C5Me5), 11.1 (s, C5Me5), –19.0 (d, J = 18 Hz, Ir-
CH) ppm. 31P{1H} NMR (202.35 MHz, C6D6, r.t.): δ = –52.1 (s)
ppm. C34H47Ir2O2P (903.16): calcd. C 42.63, H 6.54; found C
43.22, H 6.54.
A similar reaction of 1 (110 mg, 0.167 mmol) with diethyl phenyl
phosphonite (39.7 mg, 0.200 mmol) gave 2d as a yellow-orange
powder (80.1 mg, 0.0936 mmol, 56%). 1H NMR (500.00 MHz,
C6D6, r.t.): δ = 7.99 (m, 1 H, aromatic), 7.28 (t, J = 7 Hz, 1 H,
aromatic), 7.11 (t, J = 7 Hz, 1 H, aromatic), 7.04 (m, 1 H, aro-
matic), 3.78 (td, J = 9, 7 Hz, 2 H, OCH2CH3), 3.46 (br. s, 2 H,
OCH2CH3), 1.94 (s, 15 H, Cp*), 1.92 (d, J = 2 Hz, 15 H, Cp*),
A similar reaction of 1 (80.2 mg, 0.122 mmol) with triethyl phos-
phite (28.0 mg, 0.169 mmol) gave 4 as yellow crystals (81%, deter-
1
mined by 31P{1H} NMR). H NMR (500.00 MHz, C6D6, r.t.): δ =
1.16 (t, J = 7 Hz, 6 H, OCH2CH3), –17.41 (br. s, 3 H, Ir-H) ppm. 4.03–3.86 (m, 6 H, OCH2CH3), 3.33–3.32 (m, 1 H, C5Me4CH2Ir),
1H NMR (500.00 MHz, CD2Cl2, –90 °C): δ = 7.39 (m, 1 H, aro-
matic), 6.77 (m, 2 H, aromatic), 6.69 (m, 1 H, aromatic), 3.75 (m,
2.75 (d, J = 7 Hz, 1 H, C5Me4CH2Ir), 2.15 (m, 3 H, C5Me4CH2Ir),
2.08 (s, 15 H, Cp*), 1.89 (m, 3 H, C5Me4CH2Ir), 1.67 (m, 3 H,
1 H, OCH2CH3), 3.51 (m, 2 H, OCH2CH3), 2.73 (m, 1 H, C5Me4CH2Ir), 1.37 (m, 3 H, C5Me4CH2Ir), 1.18 (t, J = 8 Hz, 6 H,
OCH2CH3), 1.83 (s, 15 H, Cp*), 1.75 (d, J = 2 Hz, 15 H, Cp*),
1.33 (t, J = 7 Hz, 3 H, OCH2CH3), 1.03 (t, J = 7 Hz, 3 H,
OCH2CH3), –17.07 (d, J = 37 Hz, 1 H, Ir-H), –18.13 (d, J = 25 Hz,
1
H, Ir-H), –19.87 (s,
1
H, Ir-H) ppm. 13C{1H} NMR
OCH2CH3), –15.06 (s, 1 H, Ir-H), –18.00 (d, J = 28 Hz, 1 H, Ir- (125.65 MHz, C6D6, r.t.): δ = 88.2 (s, C5Me5), 60.6 (s, OCH2CH3),
H), –20.60 (d, J = 11 Hz, 1 H, Ir-H-Ir) ppm. 13C{1H} NMR
(125.65 MHz, C6D6, r.t.): δ = 160.7 (d, J = 102 Hz, P-C), 149.4 (d,
J = 38 Hz, Ir-C), 142.8 (d, J = 22 Hz, aromatic), 129.4 (d, J =
8 Hz, aromatic), 128.1 (d, J = 2 Hz, aromatic), 119.2 (d, J = 9 Hz,
aromatic), 94.6 (d, J = 4 Hz, C5Me5), 90.0 (s, C5Me5), 59.5 (d, J =
6 Hz, OCH2CH3), 15.9 (d, J = 8 Hz, OCH2CH3), 10.96 (s, C5Me5),
10.49 (s, C5Me5) ppm. 31P{1H} NMR (202.35, C6D6, r.t.): δ = 93.4
(s) ppm. M.p. 108 °C (dec.). C30H47Ir2O2P (855.10): calcd. C 42.14,
H 5.56; found C 42.05, H 5.54.
16.2 (d, J = 7 Hz, OCH2CH3), 11.8 (s, C5Me4CH2Ir), 11.1 (s,
C5Me5), 10.5 (d, J = 3 Hz, C5Me4CH2Ir), 10.2 (s, C5Me4CH2Ir),
8.1 (s, C5Me4CH2Ir), –25.3 (s, C5Me4CH2Ir) ppm. 31P{1H} NMR
(202.35, C6D6, r.t.): δ = 70.5 (s) ppm. C26H47Ir2O3P (823.06): calcd.
C 37.94, H 5.76; found C 37.94, H 5.47.
Reaction of 1 with Dimethyl Sulfoxide To Give 5: A two-necked
30 mL flask was charged with 1 (552 mg, 0.839 mmol) in benzene
(3.0 mL). Dimethyl sulfoxide (326 mg, 4.17 mmol) was added to
the reaction mixture, and this was stirred for 64 h. After removal
of the volatiles in vacuo, the residue was extracted with benzene to
give 5 as a brown powder (428 mg, 0.582 mmol, 69%). Single crys-
tals suitable for X-ray analysis were obtained by cooling of a hex-
ane solution of 5. 1H NMR (500.00 MHz, CD2Cl2, –80 °C): δ =
4.61 (d, J = 9 Hz, 1 H, Ir-CHH), 3.12 (s, 3 H, SMe), 2.56 (s, 1 H,
Ir-CHH), 1.98 (s, 15 H, Cp*), 1.87 (s, 15 H, Cp*), –13.38 (s, 1 H,
Ir-H), –17.24 (s, 1 H, Ir-H), –20.68 (s, 1 H, Ir-H) ppm. 13C{1H}
NMR (125.65 MHz, CD2Cl2, –80 °C): δ = 92.0 (s, C5Me5), 89.2 (s,
C5Me5), 42.9 (s, SMe), 12.0 (s, S-CH2-Ir), 10.4 (s, C5Me5), 10.3 (s,
C5Me5) ppm. M.p. 121 °C (dec.). C22H38Ir2OS (735.04): calcd. C
35.95, H 5.21; found C 35.53, H 4.91.
A similar reaction of 1 (84.0 mg, 0.128 mmol) with ethyl diphenyl
phosphinite (33.8 mg, 0.147 mmol) gave 2e as an orange powder
1
(69.8 mg, 0.0787 mmol, 61%). H NMR (500.00 MHz, C6D6, r.t.):
δ = 7.95 (m, 1 H, aromatic), 7.70 (m, 2 H, aromatic), 7.46 (m, 1 H,
aromatic), 7.16 (m, 2 H, aromatic), 7.05 (m, 2 H, aromatic), 6.96
(m, 1 H, aromatic), 3.58 (m, 1 H, OCHHCH3), 3.17 (m, 1 H,
OCHHCH3), 1.97 (d, J = 2 Hz, 15 H, Cp*), 1.59 (s, 15 H, Cp*),
0.93 (t, J = 7 Hz, 3 H, OCH2CH3), –17.41 (br. s, 3 H, Ir-H) ppm.
1H NMR (500.00 MHz, CD2Cl2, –90 °C): δ = 7.40 (m, 1 H, aro-
matic), 7.17 (m, 5 H, aromatic), 6.89–6.83 (m, 3 H, aromatic), 3.61
(m, 1 H, OCHHCH3), 2.92 (m, 1 H, OCHHCH3), 1.86 (s, 15 H,
Cp*), 1.35 (s, 15 H, Cp*), 1.07 (m, 3 H, OCH2CH3), –15.06 (s, 1 Reaction of 1 with Methyl Phenyl Sulfoxide To Give 6a: A two-
H, Ir-H), –17.04 (d, J = 28 Hz, 1 H, Ir-H), –21.48 (d, J = 7 Hz, 1
necked 30 mL flask was charged with 1 (443 mg, 0.674 mmol) in
H, Ir-H-Ir) ppm. 13C{1H} NMR (125.65 MHz, C6D6, r.t.): δ = benzene (2.0 mL). Methyl phenyl sulfoxide (287 mg, 2.05 mmol)
159.6 (d, J = 100 Hz, P-C), 147.6 (d, J = 38 Hz, Ir-C), 143.0 (d, J was added to the reaction mixture, and this was stirred for 40 h.
= 21 Hz, aromatic), 141.5 (d, J = 60 Hz, aromatic), 132.0 (d, J =
10 Hz, aromatic), 130.8 (d, J = 8 Hz, aromatic), 129.8 (s, aromatic),
128.0 (s, aromatic), 127.5 (d, J = 10 Hz, aromatic), 119.9 (d, J =
9 Hz, aromatic), 95.0 (d, J = 3 Hz, C5Me5), 90.2 (s, C5Me5), 59.9
(d, J = 4 Hz, OCH2CH3), 16.0 (d, J = 8 Hz, OCH2CH3), 11.2 (s,
After removal of the volatiles in vacuo, the residue was washed
with hexane then extracted with benzene to give 6a as a yellow-
brown powder (501 mg, 0.629 mmol, 93%). Single crystals suitable
for X-ray analysis were obtained from a hot hexane solution of 6a.
1H NMR (500.00 MHz, C6D6, r.t.): δ = 7.82 (d, J = 7 Hz, 1 H,
C5Me5), 10.3 (s, C5Me5) ppm. 31P{1H} NMR (202.35, C6D6, r.t.): aromatic), 7.65 (d, J = 7 Hz, 1 H, aromatic), 6.98 (m, 2 H, aro-
Eur. J. Inorg. Chem. 2008, 4360–4368
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
4365

Y. Takahashi, K.-i. Fujita, R. Yamaguchi
FULL PAPER
matic), 3.47 (s, 3 H, Me), 1.88 (s, 15 H, Cp*), 1.81 (s, 15 H, Cp*), (m, 1 H, aromatic), 7.68 (m, 1 H, aromatic), 7.55 (m, 2 H, aro-
–15.27 (br., 2 H, Ir-H), –19.57 (br., 1 H, Ir-H) ppm. 1H NMR matic), 7.03–6.99 (m, 2 H, aromatic), 6.95–6.88 (m, 2 H, aromatic),
(500.00 MHz, CD2Cl2, –90 °C): δ = 7.37 (d, J = 7 Hz, 1 H, aro-
matic), 6.85 (d, J = 7 Hz, 1 H, aromatic), 6.80 (t, J = 7 Hz, 1 H,
aromatic), 6.74 (t, J = 7 Hz, aromatic), 3.27 (s, 3 H, Me), 1.86 (s,
6.83 (m, 1 H, aromatic), 1.95 (s, 15 H, Cp*), 1.63 (s, 15 H, Cp*),
–15.89 (s, 3 H, Ir-H) ppm. 1H NMR (500.00 MHz, CD2Cl2,
–90 °C): δ = 7.44 (m, 1 H, aromatic), 7.26 (m, 3 H, aromatic), 7.07
15 H, Cp*), 1.82 (s, 15 H, Cp*), –14.93 (s, 1 H, Ir-H), –15.83 (s, 1 (m, 2 H, aromatic), 6.86 (m, 3 H, aromatic), 2.02 (s, 15 H, Cp*),
H, Ir-H), –19.57 (s, 1 H, Ir-H) ppm. 13C{1H} NMR (125.65 MHz,
C6D6, r.t.): δ = 169.1 (s, aromatic), 144.2 (s, aromatic), 139.5 (s,
aromatic), 128.4 (s, aromatic), 124.4 (s, aromatic), 120.6 (s, aro-
matic), 94.9 (s, C5Me5), 90.3 (s, C5Me5), 59.9 (s, SMe), 10.6 (s,
1.47 (s, 15 H, Cp*), –15.39 (s, 1 H, Ir-H), –16.03 (s, 1 H, Ir-H),
–16.83 (s, 1 H, Ir-H) ppm. 13C{1H} NMR (125.65 MHz, C6D6,
r.t.): δ = 165.3 (s, aromatic), 157.5 (s, aromatic), 144.5 (s, aromatic),
142.2 (s, aromatic), 130.0 (s, aromatic), 129.1 (s, aromatic), 128.5
C5Me5), 10.5 (s, C5Me5) ppm. M.p. 155 °C (dec.). C27H40Ir2OS (s, aromatic), 126.2 (s, aromatic), 127.6 (s, aromatic), 120.6 (s, aro-
(797.10): calcd. C 40.68, H 5.06; found C 40.89, H 4.81.
matic), 95.3 (s, C5Me5), 90.7 (s, C5Me5), 10.6 (s, C5Me5), 10.4 (s,
C5Me5) ppm. M.p. 109 °C (dec.). C32H42Ir2OS (859.17): calcd. C
44.73, H 4.93; found C 45.03, H 4.87.
Reaction of 1 with Diphenyl Sulfoxide to Give 6b: A two-necked
30 mL flask was charged with 1 (142 mg, 0.216 mmol) in benzene
(0.6 mL). Diphenyl sulfoxide (45.2 mg, 0.223 mmol) was added to X-ray Structure Analyses of 2a, 4, 5, and 6a: The crystallographic
the reaction mixture, and this was stirred for 48 h at 35 °C. After
removal of the volatiles in vacuo, the residue was washed with hex-
ane and extracted with benzene to give 6b as a brown powder (79 g,
data and experimental details for 2a, 4, 5, and 6a are summarized
in Table 1. Diffraction data for 2a, 4, 5, and 6a were obtained with
a Rigaku RAXIS RAPID instrument. Reflection data for 2a, 4, 5,
0.091 mmol, 42%). 1H NMR (500.00 MHz, C6D6, r.t.): δ = 7.90 and 6a were corrected for Lorentz and polarization effects. Numer-
Table 1. Crystallographic data and structure refinement parameters for 2a, 4, 5, and 6a.
2a
4
5
6a
Description of Crystal
Color, habit
Max. crystal dim. [mm]
Crystallographic system
Space group
a [Å]
b [Å]
c [Å]
α [°]
β [°]
orange, block
0.10ϫ0.10ϫ0.07
triclinic
yellow, platelet
0.13ϫ0.13ϫ0.04
triclinic
yellow, block
0.26ϫ0.14ϫ0.12
monoclinic
P21/c (#14)
15.7174(3)
8.9219(3)
17.2809(4)
90
104.3353(7)
90
2347.84(9)
4
orange, block
0.23ϫ0.16ϫ0.14
monoclinic
P21/n (#14)
8.53486(15)
17.6525(3)
17.3759(3)
90
93.1088(7)
90
2614.03(8)
4
¯
¯
P1 (#2)
P1 (#2)
9.2907(18)
10.801(2)
13.642(3)
90.862(6)
92.084(8)
99.095(7)
1350.5(5)
2
8.6369(5)
11.1296(7)
16.8625(9)
73.4397(19)
76.9323(16)
66.349(2)
1411.61(14)
2
γ [°]
V [Å3]
Z
Formula
C28H43Ir2P
795.06
1.955
C26H47Ir2O3P
823.07
1.936
C22H38Ir2SO
735.04
2.079
C27H40Ir2SO
797.11
2.025
FW [gmol–1]
Dcalc [gcm–3]
Data Collection
Radiation (λ [Å])
Temperature [K]
No. of data images
ω oscillation range
(χ = 45.0, φ = 0.0) [°]
Exposure rate [sdeg–1]
ω oscillation range
(χ = 45.0, φ = 180.0) [°]
Exposure rate (s/deg)
Detector position [mm]
Pixel size [mm]
2θmax [°]
Mo-Kα (λ = 0.71075 Å)
173
110
130.0–190.0
Mo-Kα (λ = 0.71075 Å)
173
110
130.0–190.0
Mo-Kα (λ = 0.71075 Å)
173
110
130.0–190.0
Mo-Kα (λ = 0.71075 Å)
173
110
130.0–190.0
300
0.0–160.0
300
0.0–160.0
300
0.0–160.0
300
0.0–160.0
300
300
127.40
0.100
55.0
300
127.40
0.100
54.9
300
127.40
0.100
54.9
127.40
0.100
55.0
No. of reflections measured total: 13254
unique: 6122
total: 13999
unique: 6459
(Rint = 0.092)
total: 22344
unique: 5363
(Rint = 0.054)
total: 25410
unique: 5958
(Rint = 0.076)
(Rint = 0.060)
Structure Determination
No. of observations
No. of variables
4249
320
2969
288
4268
270
5061
317
Reflection/paramater ratio
Absorbance correction
Transmission factor
R [IϾ3.00σ(I)][a]
13.28
10.31
15.81
15.97
multiscan
0.392–0.499
0.0335
0.0428[b]
0.992
multiscan
0.146–0.683
0.0622
0.0985[c]
1.002
numerical
0.211–0.253
0.0339
0.0527[d]
1.010
numerical
0.234–0.237
0.0325
0.0470[e]
1.008
Rw [IϾ3.00σ(I)][a]
Goodness of fit indicator
[a] R = Σ||Fo| – |Fc||/Σ|Fo|, Rw = [Σw(|Fo| – |Fc|)2/ΣwFo
]
2 1/2. [b] 1/[1.0000σ(Fo2)]. [c] 1/[0.0054Fo + 1.0000σ(Fo2)]. [d] 1/[0.0011Fo
+
2
2
2
1.0000σ(Fo2)]. [e] 1/[0.0002Fo + 1.0000σ(Fo2)].
4366
www.eurjic.org
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2008, 4360–4368

Addition of C–H Bonds to a Dinuclear IrII Complex
Haddleton, R. N. Perutz, J. Chem. Soc., Chem. Commun. 1986,
1734–1736; e) P. A. Chetcuti, C. B. Knobler, M. F. Hawthorne,
Organometallics 1988, 7, 650–660; f) T. W. Bell, S.-A. Brough,
M. G. Partridge, R. N. Perutz, A. D. Rooney, Organometallics
1993, 12, 2933–2941; g) P. Burger, R. G. Bergman, J. Am.
Chem. Soc. 1993, 115, 10462–10463; h) B. A. Arndtsen, R. G.
Bergman, Science 1995, 270, 1970–1972.
a) K. Fujita, T. Hamada, R. Yamaguchi, J. Chem. Soc., Dalton
Trans. 2000, 1931–1936; b) K. Fujita, H. Nakaguma, F. Hana-
saka, R. Yamaguchi, Organometallics 2002, 21, 3749–3757; c)
K. Fujita, H. Nakaguma, T. Hamada, R. Yamaguchi, J. Am.
Chem. Soc. 2003, 125, 12368–12369.
ical or empirical absorption corrections were applied. The struc-
tures of 2a, 4, 5, and 6a were solved by the heavy-atom Patterson
method,[21,22] and refined anisotropically for non-hydrogen atoms
by full-matrix least-squares calculations, except for the carbon and
oxygen atoms in the triethyl phosphite ligand of 4 which were re-
fined isotropically. Atomic scattering factors and anomalous dis-
persion terms were taken from the literature.[23] The location of the
metal hydrides could not be determined. Other hydrogen atoms
were located on the idealized positions. Calculations were per-
formed using the program system CrystalStructure.[24,25]
[7]
[8]
CCDC-686348 (for 2a), -686349 (for 4), -686350 (for 5), and
-686351 (for 6a) contain the supplementary crystallographic data
for this paper. These data can be obtained free of charge from The
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif.
These coupling constants had larger values compared to those
2
in free dimethyl(phenyl)phosphane (1JPC = 16 Hz and JPC
=
18 Hz). Although the increase of the P–C coupling constant in
phosphorus ligands resulting from their coordination to transi-
tion metal centers is generally known, an abnormally large 1JPC
was observed in the cases of complexes 2a–e. We suppose that
the delocalization of electrons in the diiridacycle of 2a–e might
give rise to “ylidic” character of the P–C bond, which would
cause this increase in the coupling constants.
[1] a) R. H. Crabtree, The Organometallic Chemistry of the Transi-
tion Metals, 4th ed., John Wiley & Sons, Inc., New Jersey, 2005,
ch. 13; b) R. D. Adams in Comprehensive Organometallic
Chemistry II (Eds: E. W. Abel, F. G. A. Stone, G. Wilkinson),
Pergamon, New York, 1995, vol. 10; c) J. Halpern, Inorg. Chim.
Acta 1982, 62, 31–37; d) H. Suzuki, Eur. J. Inorg. Chem. 2002,
1009–1023.
[9]
T. M. Gilbert, R. G. Bergman, J. Am. Chem. Soc. 1985, 107,
3502–3507.
–
[10]
There are many examples of 34 e bimetallic system with bridg-
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