Binuclear Methylborole Iron Carbonyls: Iron鈭扞ron Multiple Bonds and Perpendicular Structures

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• 作者：Jianlin Chen ; Shaolin Chen ; Liu Zhong ; Hao Feng ; Yaoming Xie ; R. Bruce King
• 刊名：Inorganic Chemistry
• 出版年：2011
• 出版时间：February 21, 2011
• 年：2011
• 卷：50
• 期：4
• 页码：1351-1360
• 全文大小：1083K
• 年卷期：v.50,no.4(February 21, 2011)
• ISSN：1520-510X

文摘

Methylborole iron tricarbonyl, (畏⁵-C₄H₄BCH₃)Fe(CO)₃, is known experimentally and is a potential source of binuclear (C₄H₄BCH₃)₂Fe₂(CO)_n (n = 5, 4, 3, 2, 1) derivatives through reactions such as photolysis. In this connection the lowest energy (C₄H₄BCH₃)₂Fe₂(CO)₅ structures are predicted theoretically to have a single bridging carbonyl group and Fe鈭扚e distances consistent with formal single bonds. The lowest energy (C₄H₄BCH₃)₂Fe₂(CO)₄ structures have two bridging carbonyl groups and Fe鈺怓e distances suggesting formal double bonds. Analogously, the lowest energy (C₄H₄BCH₃)₂Fe₂(CO)₃ structures have three bridging carbonyl groups and very short Fe鈮e distances suggesting formal triple bonds. The tetracarbonyl (C₄H₄BCH₃)₂Fe₂(CO)₄ is predicted to be thermodynamically unstable toward disproportionation into (C₄H₄BCH₃)₂Fe₂(CO)₅ + (C₄H₄BCH₃)₂Fe₂(CO)₃, whereas the tricarbonyl is thermodynamically viable toward analogous disproportionation. The lowest energy structures of the more highly unsaturated methylborole iron carbonyls (C₄H₄BCH₃)₂Fe₂(CO)_n (n = 2, 1) have hydrogen atoms bridging an iron鈭抍arbon bond. In addition, the lowest energy (C₄H₄BCH₃)₂Fe₂(CO) structures are 鈥渟lipped perpendicular鈥?structures with bridging methylborole ligands, a terminal carbonyl group, and agostic CH₃鈫扚e interactions involving the methyl hydrogens. Thus, in these highly unsaturated systems the methyl substituent in the methylborole ligand chosen in this work is not an 鈥渋nnocent bystander鈥?but instead participates in the metal鈭抣igand bonding.