Multistep Self-Assembly of Heteroleptic Magnesium and Sodium−Magnesium Benzamidinate Complexes

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• 作者：Robert Forret ; Alan R. Kennedy ; Jan Klett ; Robert E. Mulvey ; Stuart D. Robertson
• 刊名：Organometallics
• 出版年：2010
• 出版时间：March 22, 2010
• 年：2010
• 卷：29
• 期：6
• 页码：1436-1442
• 全文大小：828K
• 年卷期：v.29,no.6(March 22, 2010)
• ISSN：1520-6041

文摘

Reaction of the magnesium bis-alkyl Mg(CH₂SiMe₃)₂ and the sodium amide NaHMDS (where HMDS = N(SiMe₃)₂) with benzonitrile yields the homometallic heteroleptic complex [PhC(NSiMe₃)₂Mg{μ-NC(CH₂SiMe₃)Ph}]₂ (1). It appears that at least six independent reactions must have occurred in this one-pot reaction to arrive at this mixed benzamidinate ketimido product. Two benzonitrile solvated derivatives of Mg(CH₂SiMe₃)₂ (5a and 5b) have been synthesized, with 5a crystallographically characterized as a centrosymmetric (MgC)₂ cyclodimer. When, the components of 5a are allowed to react for longer, partial addition of the Mg-alkyl unit across the C≡N triple bond occurs to yield the trimeric species (Me₃SiCH₂)₂Mg₃[μ-N═C(CH₂SiMe₃)Ph]₄·2N≡CPh (6), with bridging ketimido groups and terminal alkyl groups. Finally, using the same starting materials as that which produced 1, but altering their order of addition, a magnesium bis-alkyl unit is inserted into the Na−N bonds of a benzamidinate species to yield a new sodium magnesiate complex, PhC(NSiMe₃)₂Mg(μ-CH₂SiMe₃)₂Na·2TMEDA (7). The formation of 7 represents a novel (insertion) route to mixed-metal species of this kind and is the first such example to contain a bidentate terminal anion attached to the divalent metal center. All new species are characterized by ¹H and ¹³C NMR spectroscopy and where appropriate by IR spectroscopy. The solid-state structures of complexes 1, 5a, and 7 have also been determined and are disclosed within.