Synthesis and Small Molecule Reactivity of trans-Dihydride Isomers of Ru(NHC)2(PPh3)2H2 (NHC = N-Heterocyclic Carbene)

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• 作者：Caroline J. E. Davies ; John P. Lowe ; Mary F. Mahon ; Rebecca C. Poulten ; Michael K. Whittlesey
• 刊名：Organometallics
• 出版年：2013
• 出版时间：September 9, 2013
• 年：2013
• 卷：32
• 期：17
• 页码：4927-4937
• 全文大小：640K
• 年卷期：v.32,no.17(September 9, 2013)
• ISSN：1520-6041

文摘

Addition of IMe₄ (1,3,4,5-tetramethylimidazol-2-ylidene) to Ru(PPh₃)₃HCl (in the presence of H₂) or Ru(PPh₃)₄H₂ gave the all-trans isomer of Ru(IMe₄)₂(PPh₃)₂H₂ (1a), whereas 1,3-diethyl-4,5-dimethylimidazol-2-ylidene (IEt₂Me₂) reacted with Ru(PPh₃)₄H₂ to form cis,cis,trans-Ru(IEt₂Me₂)₂(PPh₃)₂H₂ (2b). H/D exchange of 1a with C₆D₆ (elevated temperature) or D₂ (room temperature) gave Ru(IMe₄)₂(PPh₃)₂HD (1a-HD) and Ru(IMe₄)₂(PPh₃)₂D₂ (1a-D₂). CO reacted with 1a to give a mixture of Ru(IMe₄)₂(PPh₃)(CO)H₂ (3) and Ru(IMe₄)₂(CO)₃ (4); 2b reacted in a similar manner, although more slowly, allowing isolation of the monocarbonyl species Ru(IEt₂Me₂)₂(PPh₃)(CO)H₂ (5). Insertion of CO₂ into one of the Ru鈥揌 bonds of 1a and 2b generated mixtures of major and minor isomers of the 魏²-formate complexes Ru(IMe₄)₂(PPh₃)(OCHO)H (7/8) and Ru(IEt₂Me₂)₂(PPh₃)(OCHO)H (9/10). The hydridic nature of 1a and 2b was apparent by their reactivity toward MeI, which gave [Ru(IMe₄)₂(PPh₃)₂H]I (11), Ru(IEt₂Me₂)₂(PPh₃)HI (12), [Ru(IEt₂Me₂)₂(PPh₃)₂H]I (13), and Ru(IEt₂Me₂)(PPh₃)₂HI (14). Complexes 1a, 2b, 5, 9, 11, 13, and 14 were structurally characterized.