Structure and Bonding of a Zwitterionic Iridium Complex Supported by a Phosphine with the Parent Carba-closo-dodecaborate CB11H11鈥?/sup> Ligand Substituent

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• 作者：Ahmad El-Hellani ; Christos E. Kefalidis ; Fook S. Tham ; Laurent Maron ; Vincent Lavallo
• 刊名：Organometallics
• 出版年：2013
• 出版时间：December 9, 2013
• 年：2013
• 卷：32
• 期：23
• 页码：6887-6890
• 全文大小：255K
• 年卷期：v.32,no.23(December 9, 2013)
• ISSN：1520-6041

文摘

A zwitterionic iridium complex of a phosphine, bearing the carba-closo-dodecaborate anion as a ligand substituent, is reported. When tethered directly to a phosphine ligand, the CB<sub>11sub>H<sub>11sub><sup>鈥?/sup> R group engages in agostic-like bonding, utilizing the B鈥揌 bonds adjacent to the carbon atom in the cluster. Evidence for the interactions is observed in solution by variable-temperature NMR and also in the solid state by a single-crystal X-ray diffraction study. The bonding between the cluster and the iridium center has also been analyzed computationally and can be described as a double agostic bonding augmented by an overlap of the skeletal electrons of the cluster with the d<sub>z<sup>2sup>sub> orbital of the metal. A significant lengthening of a trans-olefin C鈥揅 bond suggests that this ligand substituent has a pronounced trans influence, which is in contrast to the unfunctionalized weakly coordinating HCB<sub>11sub>H<sub>11sub><sup>鈥?/sup> anion.