New Acyclic (蟺-Allyl)-closo-rhodacarboranes with an Agostic CH3路路路Rh Bonding Interaction That Operate as Unmodified Rhodium-Based Catalysts for Alkene Hydroformylation

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• 作者：Konstantin I. Galkin ; Sergey E. Lubimov ; Ivan A. Godovikov ; Fedor M. Dolgushin ; Alexander F. Smol鈥檡akov ; Elena A. Sergeeva ; Vadim A. Davankov ; Igor T. Chizhevsky
• 刊名：Organometallics
• 出版年：2012
• 出版时间：September 10, 2012
• 年：2012
• 卷：31
• 期：17
• 页码：6080-6084
• 全文大小：286K
• 年卷期：v.31,no.17(September 10, 2012)
• ISSN：1520-6041

文摘

A series of new agostic (CH₃路路路Rh) (蟺-allyl)-closo-rhodacarboranes (蟺-allyl = 1,1-dimethylallyl, 1,2-dimethylallyl, 1,1,2-trimethylallyl, 1,2,3-trimethylallyl), stable in the solid state, have been synthesized via one-pot reactions between the K⁺ salts of the [7-R-8-R鈥?7,8-nido-C₂B₉H₁₀]^{鈭?/sup> monoanions (1a, R = R鈥?= Me; 1b, R,R鈥?= 渭-(o-xylylene); 1c, R,R鈥?= 渭-(CH₂)₃) and the di-渭-chloro cyclooctene rhodium dimer [(畏2-C₈H₁₄)₄Rh₂(渭-Cl)₂] (2) in the presence of a 3-fold excess of the conjugated 1,3-dienes 2-methylbuta-1,3-diene (isoprene, 3), 2,3-dimethylbuta-1,3-diene (4), and 3-methylpenta-1,3-diene (5). The agostic structures of [3-{(1鈥?-畏3)-1,1-dimethylallyl}-1,2-(CH₃)₂-3,1,2-closo-RhC₂B₉H₉] (7a) and [3-{(1鈥?-畏3)-1,1,2-trimethylallyl}-1,2-(CH₃)₂-3,1,2-closo-RhC₂B₉H₉] (8a) have been unambiguously confirmed by single-crystal X-ray diffraction studies. Two of these 蟺-allyl complexes prepared were evaluated for their efficacy in hydroformylation of the model alkenes under syngas (CO/H₂) using supercritical carbon dioxide (scCO₂) as the solvent, and both display excellent conversion and high regioselectivity in the formation of aldehyde products.}