Synthesis, Properties, and Reactivity with Carbon Dioxide of (allyl)2Ni(L) Complexes

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• 作者：Jianguo Wu ; Nilay Hazari ; Christopher D. Incarvito
• 刊名：Organometallics
• 出版年：2011
• 出版时间：June 13, 2011
• 年：2011
• 卷：30
• 期：11
• 页码：3142-3150
• 全文大小：942K
• 年卷期：v.30,no.11(June 13, 2011)
• ISSN：1520-6041

文摘

A family of nickel allyl complexes of the type (allyl)₂Ni(L) (L = PMe₃ (1), PEt₃ (2), PPh₃ (3), NHC (4); NHC = 1,3-bis(2,6-diisopropylphenyl)-4,5-dihydro-2H-imidazol-2-ylidene) and (2-methylallyl)₂Ni(L) (L = PMe₃ (5), PEt₃ (6), PPh₃ (7), NHC (8)) have been prepared using literature methods. Compounds 5, 7, and 8 were characterized by X-ray crystallography. Whereas compounds 5 and 7 are 18-electron species with two 畏³-allyl ligands, the NHC-supported complexes are 16-electron species with one 畏¹- and one 畏³-allyl ligand. Using DFT we have identified the key factors in predicting whether complexes of the type (allyl)₂M(L) (M = Ni, Pd) are 16- or 18-electron species. Compounds 1, 2, and 5鈥?b>8 readily decompose to give a mixture of products, while compound 4 decomposes to give the unusual Ni⁰ species (畏⁴-1,5-hexadiene)Ni(NHC) (9), which was characterized by X-ray crystallography. The reactions of 1鈥?b>8 with CO₂ were investigated. Compounds 5鈥?b>8 react rapidly with CO₂ at low temperature to form well-defined unidentate nickel carboxylates of the type (畏³-2-methylallyl)Ni(OC(O)C₄H₇)(L) (L = PMe₃ (10), PEt₃ (11), PPh₃ (12), NHC (13)). The structure of 13 was elucidated using X-ray crystallography. In contrast, compounds 1鈥?b>4 do not react with CO₂. We believe that the difference in reactivity between the 2-methylallyl-supported complexes and the allyl-supported complexes is related to the mechanism of CO₂ insertion.