ONO Dianionic Pincer-Type Ligand Precursors for the Synthesis of 蟽,蟺-Cyclooctenyl Iridium(III) Complexes: Formation Mechanism and Coordination Chemistry

详细信息    查看全文

• 作者：Duc Hanh Nguyen ; Ingo Greger ; Jes煤s J. P茅rez-Torrente ; M. Victoria Jim茅nez ; F. Javier Modrego ; Fernando J. Lahoz ; Luis A. Oro
• 刊名：Organometallics
• 出版年：2013
• 出版时间：December 9, 2013
• 年：2013
• 卷：32
• 期：23
• 页码：6903-6917
• 全文大小：658K
• 年卷期：v.32,no.23(December 9, 2013)
• ISSN：1520-6041

文摘

The 蟽,蟺-cyclooctenyl iridium(III) pincer compounds [Ir(魏³-pydc-X)(1-魏-4,5-畏-C₈H₁₃)] (X = H (1), Cl, Br) have been prepared from [Ir(渭-OMe)(cod)]₂ and the corresponding 4-substituted pyridine-2,6-dicarboxylic acids (H₂pydc-X) or, alternatively, from their lithium salts (X = H) and [Ir(cod)(CH₃CN)₂]PF₆. Deuterium labeling studies in combination with theoretical calculations have shown that formation of 1 involves a metal-mediated proton transfer in the reactive intermediate [Ir(魏²-Hpydc)(cod)], through the solvent-stabilized hydrido complex [IrH(魏³-pydc)(cod)(CH₃OH)], followed by olefin insertion. The formation of this hydrido intermediate results from solvent-assisted proton transfer through a hydrogen-bonding network, forming an eight-membered metallacycle. In contrast, reaction of [Ir(渭-OMe)(cod)]₂ with iminodiacetic acid derivatives, RN(CH₂COOH)₂, gave the stable iridium(I) mononuclear [Ir{魏²-MeN(CH₂COOH)(CH₂COO)}(cod)] (R = Me) complex having a free carboxymethyl group and the tetranuclear complex [Ir₄{魏⁴-PhN(CH₂COO)₂}₂(cod)₄] (R = Ph) with doubly deprotonated ligands. The molecular structure of the related cyclooctene complex [Ir₄{魏⁴-PhN(CH₂COO)₂}₂(coe)₈] has been determined by X-ray analysis. Reaction of 1 with monodentate N- and P-donor ligands gave the compounds [Ir(魏³-pydc)(1-魏-4,5-畏-C₈H₁₃)(L)] (L = py, BnNH₂, PPh₃, PMe₃). Reaction of 1 with the short-bite bis(diphenylphosphino)methane (dppm) afforded the mononuclear 1-dppm, with an uncoordinated P-donor atom, or the dinuclear complex 1₂-dppm as a function of the molar ratio used. Similarly, the dinuclear complexes 1₂-dppe and 1₂-dppp have been prepared using 1,2-bis(diphenylphosphino)ethane (dppe) and 1,3-bis(diphenylphosphino)propane (dppp) as bridging ligands. The diphosphine-bridged dinuclear assemblies have been obtained as two diastereoisomers in a 1:1 ratio due to the chirality of the mononuclear building block. The single-crystal X-ray structures of 1-py and 1-dppm are reported.