Three-Coordinate Beryllium 尾-Diketiminates: Synthesis and Reduction Chemistry

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• 作者：Merle Arrowsmith ; Michael S. Hill ; Gabriele Kociok-K枚hn ; Dugald J. MacDougall ; Mary F. Mahon ; Ian Mallov
• 刊名：Inorganic Chemistry
• 出版年：2012
• 出版时间：December 17, 2012
• 年：2012
• 卷：51
• 期：24
• 页码：13408-13418
• 全文大小：591K
• 年卷期：v.51,no.24(December 17, 2012)
• ISSN：1520-510X

文摘

A series of mononuclear, heteroleptic beryllium complexes supported by the monoanionic 尾-diketiminate ligand [HC{CMeNDipp}₂]^{鈭?/sup> (L; Dipp = 2,6-diisopropylphenyl) have been synthesized. Halide complexes of the form [LBeX] (X = Cl, I) and a bis(trimethylsilyl)amide complex were produced via salt metathesis routes. Alkylberyllium 尾-diketiminate complexes of the form [LBeR] (R = Me, nBu) were obtained by salt metathesis from the chloride precursor [LBeCl]. Controlled hydrolysis of [LBeMe] afforded an air-stable, monomeric 尾-diketiminatoberyllium hydroxide complex. [LBeMe] also underwent facile protonolysis with alcohols to form the corresponding 尾-diketiminatoberyllium alkoxides [LBeOR] (R = Me, tBu, Ph). High temperatures and prolonged reaction times were required for protonolysis of [LBeMe] with primary amines to yield the 尾-diketiminatoberyllium amide complexes [LBeNHR] (R = nBu, CH₂Ph, Ph). No reactions were observed between [LBeMe] and silanes, terminal acetylenes, or secondary amines. All compounds were characterized by 1H, 13C, and 9Be NMR spectroscopy and, in most cases, by X-ray crystallography. Reduction of the beryllium chloride complex with potassium metal resulted in apparent hydrogen-atom transfer between two 尾-diketiminate backbones, yielding two dimeric, potassium chloride bridged diamidoberyllium species. X-ray analysis of a cocrystallized mixture of the 18-crown-6 adducts of these species allowed unambiguous identification of the two reduced diketiminate ligands, one of which had been deprotonated at a backbone methyl substituent and the other reduced by hydride addition to the 尾-imine position. It is proposed that this process occurs by the formation of an unobserved radical anion species and intermolecular hydrogen-atom transfer by a radical-based hydrogen abstraction mechanism.}