Phosphinoalkylidene and -alkylidyne Complexes of Titanium: Intermolecular C鈥揌 Bond Activation and Dehydrogenation Reactions

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• 作者：Masahiro Kamitani ; Balazs Pinter ; Keith Searles ; Marco G. Crestani ; Anne Hickey ; Brian C. Manor ; Patrick J. Carroll ; Daniel J. Mindiola
• 刊名：Journal of the American Chemical Society
• 出版年：2015
• 出版时间：September 23, 2015
• 年：2015
• 卷：137
• 期：37
• 页码：11872-11875
• 全文大小：337K
• ISSN：1520-5126

文摘

The ethylene complex (PNP)Ti(畏²-H₂C鈺怌H₂)(CH₂^tBu) or (PNP)Ti鈺怌H^tBu(CH₂^tBu) (PNP^{鈥?/sup> = N[2-P(CHMe₂)₂-4-methylphenyl]₂) reacts with H₂CPPh₃ to form the 魏2-phosphinoalkylidene (PNP)Ti鈺怌HPPh₂(Ph) (1). Compound 1 activates benzene via the transient intermediate [(PNP)Ti鈮PPh₂] (C). By treatment of (PNP)Ti鈺怌HtBu(OTf) with LiCH₂PPh₂, 1 or its isotopologue (PNP)Ti鈺怌DPPh₂(C₆D₅) (1-d₆) can be produced by an independent route involving intermediate C, which activates benzene or benzene-d₆ and dehydrogenates cyclohexane-d₁₂. Addition of MeOTf to 1 results in elimination of benzene concomitant with the formation of the phosphonioalkylidyne complex, [(PNP)Ti鈮PPh₂Me(OTf) (2). Theoretical studies of 2 suggest a resonance structure having dominant Ti鈥揅 triple-bond character with some contribution also from a C鈥揚 multiple bond.}