Formation of Dinuclear Iridium Complexes by NHC-Supported C–H Bond Activation

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• 作者：Miguel A. EsteruelasAna M. López ; Enrique OñateAinhoa San-Torcuato ; Jui-Yi TsaiChuanjun Xia
• 刊名：Organometallics
• 出版年：2017
• 出版时间：February 13, 2017
• 年：2017
• 卷：36
• 期：3
• 页码：699-707
• 全文大小：591K
• ISSN：1520-6041

文摘

The formation of dinuclear iridium complexes by NHC-supported aryl-CH bond activation reactions is reported. Complex IrH₅(PⁱPr₃)₂ (1) reacts with 1,3-bis(3-methylimidazolium)benzene bis(tetrafluoroborate) ([C₆H₄(HImMe)₂][BF₄]₂) to give the dinuclear species {[IrH₂(PⁱPr₃)₂]₂[μ-C₆H₂(ImMe)₂]} (2), with a core formed by five fused rings. Complex 1 also reacts with 1,1′-diphenyl-3,3′-alkylenediimidazolium dihalides ([(CH₂)_n(HImC₆H₅)₂]X₂; n = 2, 3, 4). The reactions lead to the dinuclear complexes {[IrH₂(PⁱPr₃)₂]₂[μ-(CH₂)_n(ImC₆H₄)₂]} (n = 2 (3), 3 (4), 4 (5). These compounds can be described as two six-coordinate d⁶-iridium dihydride metal fragments containing an orthometalated phenylimidazolylidene, which are connected through an alkylene linker. In contrast to the diimidazolium salts, 1,1′-diphenyl-3,3′-methylenedibenzimidazolium dibromide ([CH₂(HBzImC₆H₅)₂]Br₂) reacts with 1 to give a 1:1 mixture of the mononuclear complexes IrH₂Br{κ-N-(HBzImC₆H₅)}(PⁱPr₃)₂ (6) and IrH₂{κ²-C,C-(MeBzImC₆H₄)}(PⁱPr₃)₂ (7). The latter and its analogous IrH₂{κ²-C,C-(PhBzImC₆H₄)}(PⁱPr₃)₂ (8) can be also obtained, as pure solids, by means of the reactions of 1 with 1-methyl-3-phenylbenzimidazolium tetrafluoroborate and 1,3-diphenylbenzimidazolium chloride, respectively.