Indenyl Ruthenium Complexes with an Unusual η3 Coordination

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Indenyl Ruthenium Complexes with an Unusual η3 Coordination Mode Jia Yuan,† Zhi-Jun Han,‡ Hui Peng,† Yun-Xiao Pi,† You Chen,† Sheng-Hua Liu,† and Guang-Ao Yu*,† †

Key Laboratory of Pesticide & Chemical Biology, Ministry of Education, College of Chemistry, Central China Normal University, Wuhan 430079, China ‡ Department of Chemistry, State Key Laboratory of Elemento-Organic Chemistry, Nankai University, Tianjin 300071, China S Supporting Information *

ABSTRACT: Dinuclear indenyl ruthenium complexes were prepared and characterized using X-ray crystallography. Their crystal structures revealed the first examples of indenyl complexes containing an unusual η3 coordination mode with bonding through the junction carbon and the adjacent carbons of the five- and six-membered rings of the indenyl ligand.

many organometallic compounds reveals a distinct η3, η2 bonding mode in which two of the five metal−carbon bonds are significantly longer than the other three. While η 3 coordination remains relatively rare in ground-state structures,4 “ring slippage” from η5 to η3 hapticity during the course of a chemical reaction is often responsible for the enhancements in reaction rate observed in associative substitution reactions.5 Complexes with η1 coordinated indenyl ligands, predominantly with the late transition metals, have also been reported.6 Recently, Chirik and co-workers have identified and characterized a series of [Zr(η5-ind)(η9-ind)] complexes.7 However, despite extensive research of indenyl complexes, a rather unusual η3 coordination mode with bonding through the junction carbon and the adjacent carbons of the five- and sixmembered rings of the indenyl ligand has not been reported. The related fluorenyl ytterbium complex reported by Trifonov and co-workers represents a rare example of this type of bonding.8 We now report the isolation and characterization of two examples of unprecedented η3 indenyl ruthenium complexes. We found that (2-phenyl-1H-inden-3-yl)dicyclohexylphosphine (1)9 and (2-mesityl-1H-inden-3-yl)dicyclohexylphosphine (2) could react with the cluster Ru3(CO)12 in heptane at about 100 °C to afford the simply substituted products [(2-phenyl-1H-inden-3-yl)PCy2]Ru3(CO)11 (3) and [(2-mesityl-1H-inden-3-yl)PCy2]Ru3(CO)11 (4) in 64% and 52% yields, respectively. Phosphine ligands 1 and 2 reacted with Ru3(CO)12 in p-xylene at about 138 °C to afford dinuclear ruthenium carbonyl complexes (μ 2 -η 1 :η 3 -2-phenyl-3Cy 2 PC 9 H 4 )Ru 2 (CO) 6 (5) and (μ 2 -η 1 :η 3 -2-mesityl-3Cy2PC9H4)Ru2(CO)6 (6). Compounds 5 and 6 could also be produced by thermolysis of clusters 3 and 4 in p-xylene (Scheme 2).

T

he indenyl (C9H7) ligand has played a crucial role in the development of organometallic chemistry and continues to be used in a wide range of chemical research areas.1 Although the indenyl ligand can be viewed as a benzannulated derivative of the cyclopentadienyl (C5H5) ligand, the transitionmetal complexes prepared using the indenyl ligand usually exhibit different reactivity than those prepared using the cyclopentadienyl ligand. The indenyl ligand has been widely used as an alternative to the cyclopentadienyl ligand, resulting in new and surprising synthetic routes in organometallic chemistry. The ability of the indenyl ligand to change its coordination mode, adjusting to the metals’ electronic needs, results in metal complexes with enhanced reactivity in ligand substitution reactions and gives rise to the term “the indenyl effect”.2 At least 10 coordination modes have been described for the indenyl ligand (Ind) (Scheme 1).3 The most common Scheme 1. Common Coordination Modes for Indenyl Ligands

coordination mode is η5-Ind, corresponding to the presence of five bonds between the metal center and the carbon atoms of the C5 ring, in a similar manner to that found with the η5cyclopentadienyl ligand (Cp = C5H5). In addition, hexahapto (η6-C9H7) coordination of the arene ring is also commonly observed. Careful inspection of the metrical parameters for © XXXX American Chemical Society

Received: July 24, 2014

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dx.doi.org/10.1021/om500760w | Organometallics XXXX, XXX, XXX−XXX

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C(12), and Ru(1).11 To the best of our knowledge, compounds 5 and 6 are the first examples of an indenyl complexes containing an η3 coordination mode with bonding through the junction carbon and the adjacent carbons of the five- and sixmembered rings of the indenyl ligand. The carbon−carbon bond distances are changed somewhat upon coordination to the ruthenium. For the η3 indenyl ring in 5, the C(12)−C(13), C(9)−C(10), and C(7)−C(11) distances are 1.441 (5), 1.436 (5), and 1.501 (5) Å, respectively. These are slightly elongated when compared to the corresponding bonds lengths of 1.371(5), 1.393(4), and 1.364(4) Å, respectively, found in (2-phenyl-1H-inden-3-yl)dicyclohexylphosphinium tetrafluoroborate.10 A similar effect was also observed in 6, where the C(26)−C(27), C(14)−C(15), and C(13)−C(17) distances were 1.434 (5), 1.426 (4), and 1.493 (4) Å, respectively. The C(16)−C(17), C(15)−C(16), and C(12)−C(13) are 1.393 (8), 1.378 (7), and 1.337 (7) Å, respectively, in compound 4 (Figure S17 in the Supporting Information). In addition, the corresponding bonds lengths are 1.382 (3), 1.388 (3), and 1.358 (2) Å, respectively, in [(2mesitylindenyl)dicyclohexylphosphine]-PdCl2.10 Coordination of the η3 indenyl ligand also breaks the coplanarity of the phosphorus atom and indenyl ligand. The distance of the phosphorus atom to the indenyl plane is 0.9282 and 0.8528 Å in complexes 5 and 6, respectively. The related bond angles also narrowed upon η3 coordination to ruthenium. The bond angle C(11)−C(10)−C(12) is 123.49° in 5 and was reduced from the corresponding bond angle C(8)−C(9)− C(10) of 132.02° found in (2-phenyl-1H-inden-3-yl)dicyclohexylphosphinium tetrafluoroborate.10 A similar effect was also observed in 6, where the bond angle C(13)−C(14)−C(26) is 124.30°, while the C(17)−C(16)−C(12) bond angle is 132.1(5)° in compound 4. The solid-state structures of 5 and 6 are also fully supported by the IR, NMR spectroscopic data, and elemental analysis. The IR spectra of 5 and 6 only show the terminal carbonyl absorptions at ν = 2071−1962 cm−1. The 1H NMR spectra showed signals for C6-H (5, δ = 8.26 ppm; 6, δ = 8.29 ppm) that are downfield relative to compounds 1 and 2,10 suggesting a strong electron-withdrawing effect by the two ruthenium metal centers. The appearance of the methylene signals of cyclohexyl in the high-field region is due to the ring current effect of the substituted phenyl or mesityl. This indicates that the complexes 5 and 6 are inflexible in solvent. The 13C{1H} NMR of 5 shows signals of three carbonyls as three doublets at the range of 193.6−200.9 ppm, due to couplings between 31P and 13C nuclei of one phosphine ligand and three carbonyl ligands. In particular, the signal of C3 appeared at 142.7 ppm, strongly suggesting the pronounced sp2 character. Three signals at 135.8, 122.7, and 120.5 ppm can be assigned to the η3 coordinated backbone carbons C7a, C1, and C7, respectively. The 13C{1H} NMR spectrum of 6 (194.6−200.2 ppm (RuCO), 144.7 (C3), 130.8 (C7a), 124.7 (C1), and 120.6 (C7) ppm) is very close to that observed for complex 5. The signals of this exocyclic η3 coordination mode are quite different from those of well-known cyclic η3 indenyl complexes. For example, the corresponding signals of (η3-Indenyl)Fe(CO)2−PPN+11 and Cp2Zr(μ-PPh2)2Rh(η3-Indenyl) appear in the range of 50−100 ppm.12 The 31P NMR spectra of 5 and 6 exhibit a singlet signal at 64.6 and 69.9 ppm, respectively, corresponding to the P atom attached to the ruthenium metal centers. The possible exocyclic η3 type intermediates have already been reported.13 However, the mechanism for the formation of

Scheme 2. Synthesis of Complexes 3−6

The molecular structures of 5 and 6 were unambiguously confirmed using single-crystal X-ray crystallography (Figures 1

Figure 1. Molecular structure of 5. Thermal ellipsoids are set at 30% probability. H atoms have been omitted for clarity.

Figure 2. Molecular structure of 6. Thermal ellipsoids are set at 30% probability. H atoms have been omitted for clarity.

and 2). Complexes 5 and 6 are isostructural. For 5, the μ2-2phenyl-3-Cy2PC9H4 unit chelates to the Ru (2) atom through its phosphorus atom P(1) and C(12). The lengths of C(10)− C(11) [1.459 (5) Å] and C(10)−C(12) [1.396 (6) Å] are similar. The lengths of Ru(1)−C(10) [2.259 (3) Å], Ru(1)− C(11) [2.255 (4) Å], and Ru(1)−C(12) [2.312 (4) Å] are consistent with normal Ru−C(sp2) bonding, which strongly supports the η3 coordination mode between C(10), C(11), B

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CDCl3): δ 205.4 (Ru-CO), 153.3 (Indenyl-C7a), 145.4 (d, 2JP−C = 14.2 Hz, Indenyl-C3a), 142.1 (d, 2JP−C = 7.6 Hz, Indenyl-C2), 137.5 (Ar-C), 135.9 (Ar-C), 134.9 (Ar-C), 134.3 (Ar-C), 132.0 (d, 1JP−C = 28.5 Hz, Indenyl-C3), 129.0 (Ar-C), 128.2 (Ar-C), 126.3 (indenyl-C5), 125.1 (Indenyl-C6), 123.3 (Indenyl-C7), 122.9 (Indenyl-C4), 46.9 (d, 3JP−C = 9.1 Hz, Indenyl-C1), 45.9 (d, 1JP−C = 17.8 Hz, Cy-C), 39.9 (d, 1JP−C = 18.6 Hz, Cy-C), 33.7 (Cy-C), 32.2 (Cy-C), 31.0 (Cy-C), 28.3 (Cy-C), 28.1 (Cy-C), 28.0 (Cy-C), 27.8 (Cy-C), 26.9 (Cy-C), 26.2 (Cy-C), 25.8 (Cy-C), 21.7 (CH3), 21.0 (CH3), 20.8 (CH3) ppm{1H}. 31P NMR (162 MHz, CDCl3): δ 41.3 (s) ppm. IR (νCO, cm−1): 2097(s), 2044(s), 2007(s), 1978(s). Anal. Calcd for C41H39O11PRu3: C, 47.26; H, 3.77. Found: C, 47.22; H, 3.82. Preparation of (μ2-η1:η3-2-Phenyl-3-Cy2PC9H4)Ru2(CO)6 (5). A solution of (2-phenyl-1H-inden-3-yl)dicyclohexylphosphine (1) (58 mg, 0.15 mmol) in p-xylene (10 mL) was stirred at room temperature for 5 min, and then Ru3(CO)12 (96 mg, 0.15 mmol) was added. The mixture was stirred at reflux for 5 h to give a dark red solution. The solvent was removed under reduced pressure, and the residue was chromatographed on silica with petroleum ether as eluent. Complex 5 (40 mg, 36%) was obtained as a red solid. NMR (400 MHz, CDCl3): δ 8.26 (d, 3JH−H = 8.0 Hz, 1H, Indenyl-H), 7.66−7.68 (m, 2H, IndenylH), 7.33−7.52 (m, 5H, Indenyl-H, Ar−H), 7.01 (s, 1H, Indenyl-H), 2.70 (br, 1H, Cy-H), 2.27−2.35 (m, 1H, Cy-H), 2.00 (br, 1H, Cy-H), 0.87−1.71(m, 16H, Cy-H), 0.63−0.67 (m, 1H, Cy-H), 0.42 (br, 1H, Cy-H), −0.07 (br, 1H, Cy-H) ppm. 13C{1H} NMR (101 MHz, CDCl3): δ 200.9 (d, 2JP−C = 11.1 Hz, Ru-CO), 198.8 (d, 2JP−C = 91.8 Hz, Ru-CO), 196.6 (Ru-CO), 193.6 (d, 2JP−C = 7.8 Hz, Ru-CO), 155.7 (Indenyl-C3a), 143.1 (d, 2JP−C = 8.1 Hz, Indenyl-C2), 142.7 (IndenylC3), 139.0 (Ph-C), 135.8 (d, 2JP−C = 5.2 Hz, Indenyl-C7a), 128.6 (PhC), 128.1 (Ph-C), 127.7 (Ph-C), 125.4 (indenyl-C4), 124.0, 123.9 (Indenyl-C5, Indenyl-C6), 122.7 (d, 1JP−C = 25.3 Hz, Indenyl-C1), 120.5 (Indenyl-C7), 49.7 (d, 1JP−C = 11.1 Hz, Cy-C), 40.1 (Cy-C), 36.4 (d, 1JP−C = 28.1 Hz, Cy-C), 32.7 (Cy-C), 29.7 (Cy-C), 29.0 (CyC), 27.8 (Cy-C), 27.2 (Cy-C), 27.1 (Cy-C), 26.8 (Cy-C), 26.5 (CyC), 25.8 (Cy-C) ppm. 31P{1H} NMR (162 MHz, CDCl3): δ 64.6 (s) ppm. IR (νCO, cm−1): 2069(s), 2034(s), 2002(s), 1984(s). Anal. Calcd for C33H31O6PRu2: C, 52.38; H, 4.13. Found: C, 52.28; H, 4.19. Preparation of (μ2-η1:η3-2-Mesityl-3-Cy2PC9H4)Ru2(CO)6 (6). A solution of (2-mesityl-1H-inden-3-yl)dicyclohexylphosphine (2) (65 mg, 0.15 mmol) and Ru3(CO)12 (96 mg, 0.15 mmol) in p-xylene (10 mL) was stirred at reflux for 5 h to give a dark red solution. The solvent was removed under reduced pressure, and the residue was chromatographed on silica with petroleum ether/acetone (20:1) as eluent. Complex 6 (36 mg, 30%) was obtained as an orange solid. 1H NMR (400 MHz, CDCl3): δ 8.29 (d, 3JH−H = 8.0 Hz, 1H, Indenyl-H), 7.50 (d, 3JH−H = 6.8 Hz, 1H, Indenyl-H), 7.21−7.25 (m, 1H, IndenylH), 6.97 (s, 2H, Ar-H), 6.86 (s, 1 H, Indenyl-H), 3.03 (s, 3H, CH3), 2.33 (br, 2H, Cy-H), 2.31 (s, 3H, CH3), 2.16 (s, 3H, CH3), 1.79 (br, 1H, Cy-H), 0.71−1.68 (m, 16H, Cy-H), 0.60 (br, 1H, Cy-H), 0.24 (br, 1H, Cy-H), −0.11 (br, 1H, Cy-H) ppm. 13C{1H} NMR (101 MHz, CDCl3): δ 200.2 (d, 2JP−C = 11.9 Hz, Ru-CO), 199.3 (d, 2JP−C = 91.7 Hz, Ru-CO), 196.4 (Ru-CO), 194.6 (d, 2JP−C = 23.2 Hz, Ru-CO), 151.1 (Indenyl-C3a), 144.7 (Indenyl-C3), 141.5 (d, 2JP−C = 9.2 Hz, Indenyl-C2), 136.9 (Ar-C), 136.6 (Ar-C), 136.5 (Ar-C), 135.6 (Ar-C), 130.8 (d, 2JP−C = 5.6 Hz, Indenyl-C7a), 129.3 (Ar-C), 129.0 (Ar-C), 126.6, 126.1 (Indenyl-C5, Indenyl-C6), 124.7 (d, 1JP−C = 26.1 Hz, Indenyl-C1), 123.9 (Indenyl-C4), 120.6 (Indenyl-C7), 59.0 (d, 1JP−C = 25.3 Hz, Cy-C), 42.1 (d, 1JP−C = 32.5 Hz, Cy-C), 36.27 (Cy-C), 34.32 (Cy-C), 29.4 (Cy-C), 28.1 (Cy-C), 28.1 (Cy-C), 27.9 (Cy-C), 26.8 (Cy-C), 26.4 (Cy-C), 25.8 (Cy-C), 25.7 (Cy-C), 25.4 (CH3), 23.6 (CH3), 20.9 (CH3) ppm. 31P{1H} NMR (162 MHz, CDCl3): δ 69.9 (s) ppm. IR (νCO, cm−1): 2071(s), 2037(s), 1998(s), 1979(s), 1962(s). Anal. Calcd for C36H37O6PRu2: C, 54.13; H, 4.67. Found: C, 54.22; H, 4.73. Thermolysis of Complex 3. A solution of 3 (100 mg, 0.10 mmol) in p-xylene (10 mL) was refluxed for 5 h to give a dark red solution. After removal of solvent in vacuo, the residue was chromatographed on silica with petroleum as eluent. Complex 5 (33 mg, 44%) was obtained as a red solid.

5 and 6 is still not clear to us. The coordination chemistry of various donor-substituted indenyl ligands, including indenyl phosphine,14 1-PR2-2-NR′-indene,15 aryl-indene,16 and 1-PR22-SR′-indene,17 has been widely explored. These ligands have proven to be a remarkably versatile access to a range of neutral, cationic, and zwitterionic transition-metal complexes.18 No similar coordination mode of the indenyl ligand was revealed, which suggests that both the substituted aryl and phosphine ligands are essential for the unexpected exocyclic η 3 coordination mode. In summary, dinuclear indenyl ruthenium carbonyl complexes have been prepared. Crystallographic characterization of the two examples establishes an unprecedented η3 coordination mode of the indenyl ligand, providing a new bonding mode for a ubiquitous organometallic ligand. The generality of this unusual coordination mode for indenyl complexes is presently being investigated in our laboratory.

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EXPERIMENTAL SECTION

General Procedure. Schlenk- and vacuum-line techniques were employed for all manipulations. All solvents were distilled from appropriate drying agents under argon before use. 1H, 13C{1H}, and 31 P{1 H} NMR spectra were recorded on a Bruker AV-400 spectrometer (400 MHz). Numbering of the indene moiety, in accordance with the IUPAC rules, used for assignment of the NMR spectra, but deviating from the crystallographic numbering used in Figures 1 and 2, is shown in Scheme 2. Elemental analyses were performed on a PerkinElmer 240C analyzer. IR spectra were recorded as KBr disks on an AVATAR 360 FT-IR spectrometer. (2-Phenyl-1Hinden-3-yl)dicyclohexylphosphine (1) and (2-mesityl-1H-inden-3-yl)dicyclohexylphosphine (2) were prepared according to the literature procedures.10 Preparation of [(2-Phenyl-1H-inden-3-yl)PCy2]Ru3(CO)11 (3). A solution of (2-phenyl-1H-inden-3-yl)dicyclohexylphosphine (1) (58 mg, 0.15 mmol) and Ru3(CO)12 (96 mg, 0.15 mmol) in heptane (10 mL) was stirred at reflux for 2 h to give a red solution. The solvent was removed in vacuo, and the residue was chromatographed on silica with petroleum ether as eluent. Complex 3 (96 mg, 64%) was obtained as a red solid. 1H NMR (400 MHz, CDCl3): δ 7.69 (d, 3JH−H = 8.0 Hz, 1H, Indenyl-H), 7.44−7.50 (m, 3H, Indenyl-H, Ph-H), 7.26−7.42 (m, 5H, Indenyl-H, Ph-H), 3.80 (br, 2H, Indenyl-CH2), 2.25−2.90 (m, 4H, Cy-H), 1.89 (br, 2H, Cy-H), 1.78 (br, 2H, Cy-H), 1.35−1.68 (m, 9H, Cy-H), 0.78−1.34 (5H, Cy-H) ppm. 13C{1H} NMR (101 MHz, CDCl3): δ 205.5 (Ru-CO), 152.7 (Indenyl-C7a), 144.8 (d, 2JP−C = 11.5 Hz, Indenyl-C3a), 142.2 (d, 2JP−C = 11.1 Hz, Indenyl-C2), 138.5 (PhC), 132.1 (d, 1JP−C = 11.1 Hz, Indenyl-C3), 129.0 (Ph-C), 128.3 (PhC), 128.0 (Ph-C), 126.5 (Indenyl-C5), 125.3 (Indenyl-C6), 123.4 (Indenyl-C7), 122.5 (Indenyl-C4), 48.3 (d, 3JP−C = 8.3 Hz, IndenylC1), 31.5 (d, 1JP−C = 8.2 Hz, Cy-C), 30.5 (Cy-C), 28.4 (d, 1JP−C = 14.5 Hz, Cy-C), 27.4 Cy-C), 26.2 (Cy-C) ppm. 31P{1H} NMR (162 MHz, CDCl3): δ 33.2 (s) ppm. IR (νCO, cm−1): 2097(s), 2047(s), 2016(s), 1995(s), 1942(s). Anal. Calcd for C38H33O11PRu3: C, 45.65; H, 3.33. Found: C, 45.54; H, 3.40. Preparation of [(2-Mesityl-1H-inden-3-yl)PCy2]Ru3(CO)11 (4). A solution of (2-mesityl-1H-inden-3-yl)dicyclohexylphosphine (2) (129 mg, 0.30 mmol) and Ru3(CO)12 (192 mg, 0.30 mmol) in heptane (20 mL) was stirred at reflux for 2 h to give a red solution. The solvent was removed under reduced pressure, and the residue was chromatographed on silica with petroleum ether as eluent. Complex 4 (162 mg, 52%) was obtained as a red solid. 1H NMR (400 MHz, CDCl3): δ 7.77 (d, 3JH−H = 8.0 Hz, 1H, Indenyl-H), 7.48 (d, 3JH−H = 7.2 Hz, 1H, Indenyl-H), 7.39−7.43 (m, 1H, Indenyl-H), 7.28−7.32 (m, 1H, Indenyl-H), 6.96 (s, 2H, Ar-H), 3.74 (d, 2JH−H = 23.6 Hz, 1H, Indenyl-CH2), 3.57 (d, 2JH−H = 23.6 Hz, 1H, Indenyl-CH2), 2.75 (br, 1H, Cy-H), 2.40 (br, 1H, Cy-H), 2.35 (s, 3H, CH3), 2.31 (s, 3H, CH3), 2.22 (s, 3H, CH3), 1.06−1.98 (m, 18H, Cy-H), 0.79 (br, 1H, Cy-H), −0.18 (br, 1H, Cy-H) ppm. 13C{1H} NMR (101 MHz, C

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Thermolysis of Complex 4. A solution of 4 (104 mg, 0.10 mmol) in p-xylene (10 mL) was refluxed for 5 h to give a dark red solution. After removal of solvent in vacuo, the residue was chromatographed on silica with petroleum/acetone (20:1) as eluent. Complex 6 (30 mg, 38%) was obtained as a red solid. Crystallographic Studies. Single crystals of 4, 5, and 6 for X-ray diffraction analyses were obtained by slow diffusion of hexane into their CH2Cl2 solutions at room temperature. Crystallographic data were collected on a Bruker SMART CCD area-detector diffractometer with graphite-monochromated Mo Kα radiation (λ = 0.71073 Å). Diffraction measurements were made at room temperature. An absorption correction by SADABS was applied to the intensity data. The structures were solved by the Patterson method. The remaining non-hydrogen atoms were determined from the successive difference Fourier syntheses. All non-hydrogen atoms were refined anisotropically, except those mentioned otherwise. The hydrogen atoms were generated geometrically and refined with isotropic thermal parameters. The structures were refined on F2 by full-matrix least-squares methods using the SHELXTL-97 program package.19

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Taylor, N. J.; Calabrese, J. C.; Nugent, W. A.; Christopher Roe, D.; Connaway, E.; Marder, T. B. J. Chem. Soc., Chem. Commun. 1989, 990. (5) (a) Rerek, M. E.; Basolo, F. J. Am. Chem. Soc. 1984, 106, 5908. (b) Westcott, S. A.; Kakkar, A. K.; Stringer, G.; Taylor, N. J.; Marder, T. B. J. Organomet. Chem. 1990, 394, 777. (c) Kakkar, A. K.; Jones, S. F.; Taylor, N. J.; Collins, S.; Marder, T. B. J. Chem. Soc., Chem. Commun. 1989, 1454. (6) (a) Stradiotto, M.; McGlinchey, M. J. Coord. Chem. Rev. 2001, 219−221, 311. (b) Werlé, C.; Hamdaoui, M.; Bailly, C.; Le Goff, X.-F.; Brelot, L.; Djukic, J.-P. J. Am. Chem. Soc. 2013, 135, 1715. (7) (a) Bradley, C. A.; Lobkovsky, E.; Keresztes, I.; Chirik, P. J. J. Am. Chem. Soc. 2005, 127, 10291. (b) Bradley, C. A.; Veiros, L. F.; Chirik, P. J. Organometallics 2007, 26, 3191. (c) Bradley, C. A.; Keresztes, I.; Lobkovsky, E.; Young, V. G.; Chirik, P. J. J. Am. Chem. Soc. 2004, 126, 16937. (d) Veiros, L. F. Chem.Eur. J. 2005, 11, 2505. (8) Trifonov, A. A.; Fedorova, E. A.; Fukin, G. K.; Druzhkov, N. O.; Bochkarev, M. N. Angew. Chem., Int. Ed. 2004, 43, 5045. (9) Yuan, J.; Sun, Y.; Yu, G.-A.; Zhao, C.; She, N.-F.; Mao, S.-L.; Huang, P.-S.; Han, Z.-J.; Yin, Y.; Liu, S.-H. Dalton. Trans. 2012, 41, 10309. (10) (a) Hao, X.; Yuan, J.; Yu, G.-A.; Qiu, M.-Q.; She, N.-F.; Sun, Y.; Zhao, C.; Mao, S.-L.; Yin, J.; Liu, S.-H. J. Organomet. Chem. 2012, 706−707, 99. (b) Chen, L.; Yu, G.-A.; Li, F.; Zhu, X.; Zhang, B.; Guo, R.; Li, X.; Yang, Q.; Jin, S.; Liu, C.; Liu, S.-H. J. Organomet. Chem. 2010, 695, 1768. (11) Forschner, T. C.; Cutler, A. R. Organometallics 1987, 6, 889. (12) Baker, R. T.; Tulip, T. H. Organometallics 1986, 5, 839. (13) (a) Kakkar, A. K.; Taylor, N. J.; Marder, T. B.; Shen, J. K.; Hallinan, N.; Basolo, F. Inorg. Chim. Acta 1992, 198−200, 219. (b) Albright, T. A.; Hofmann, P.; Hoffmann, R.; Lillya, C. P.; Dobosh, P. A. J. Am. Chem. Soc. 1983, 105, 3396. (14) Tan, X.; Li, B.; Xu, S.; Song, H.; Wang, B. Organometallics 2011, 30, 2308. (15) (a) Rankin, M. A.; McDonald, R.; Ferguson, M. J.; Stradiotto, M. Angew. Chem., Int. Ed. 2005, 44, 3603. (b) Rankin, M. A.; MacLean, D. F.; McDonald, R.; Ferguson, M. J.; Lumsden, M. D.; Stradiotto, M. Organometallics 2009, 28, 74. (c) Lundgren, R. J.; Stradiotto, M. Chem.Eur. J. 2008, 14, 10388. (d) Rankin, M. A.; Schatte, G.; McDonald, R.; Stradiotto, M. Organometallics 2008, 27, 6286. (e) Lundgren, R. J.; Rankin, M. A.; McDonald, R.; Schatte, G.; Stradiotto, M. Angew. Chem., Int. Ed. 2007, 46, 4732. (16) (a) Nikitin, K.; Bothe, C.; Müller-Bunz, H.; Ortin, Y.; McGlinchey, M. J. Organometallics 2012, 31, 6183. (b) Chen, D.; Zhang, X.; Xu, S.; Song, H.; Wang, B. Organometallics 2010, 29, 3418. (c) Chen, D.; Zhang, C.; Xu, S.; Song, H.; Wang, B. Organometallics 2011, 30, 676. (17) Hesp, K. D.; McDonald, R.; Ferguson, M. J.; Stradiotto, M. J. Am. Chem. Soc. 2008, 130, 16394. (18) (a) Stradiotto, M.; Hesp, K. D.; Lundgren, R. J. Angew. Chem., Int. Ed. 2010, 49, 494. (b) Lavery, C. B.; Ferguson, M. J.; Stradiotto, M. Organometallics 2010, 29, 6125. (19) Sheldrick, G. M. SHELXL-97: Program for the Refinement of Crystal Structures; University of Göttingen: Göttingen, Germany, 1997.

ASSOCIATED CONTENT

S Supporting Information *

Figures giving 1H, 31C{1H}, and 31P{1H} NMR and IR spectra for all complexes and molecular structures of 4, 5, and 6, CIF file, and tables giving crystallographic data for 4, 5, and 6. This material is available free of charge via the Internet at http:// pubs.acs.org.

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AUTHOR INFORMATION

Corresponding Author

*Fax: 86-27-67867725. E-mail: [email protected] (G.A.Y.). Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS This work was financially supported by the NSFC (Nos. 21472060, 21072071, and 21272088) and self-determined research funds of CCNU.

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REFERENCES

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dx.doi.org/10.1021/om500760w | Organometallics XXXX, XXX, XXX−XXX