2,2,4,4-Tetramethyl-2,4-disila-cyclo-butylzinkchlorid · TMEDA und verwandte Verbindungen

2,2,4,4-Tetramethyl-2,4-disila-cyclo-butylzinc Chloride · TMEDA and Related Compounds The reaction of (tmeda)lithium 2,2,4,4-tetramethyl-2,4-disila-cyclo-butanide with anhydrous zinc(II) chloride in pentane in the molar ratio of 2:1 does not yield the expected dialkylzinc derivative but the monosubstitution product 2,2,4,4-Tetramethyl-2,4-disila-cyclo-butylzinc chloride · tmeda 1 . This derivative crystallizes in the orthorhombic space group Pnma with a = 1 235.0(1); b = 1 696.8(2); c = 1 148.0(1) pm and Z = 4. The Zn? C bond lengths lie with 198,4 pm in the characteristic region for compounds containing a tetrahedrally coordinated zinc atom. The thermolysis of 1 leads under elimination of ZnCl₂ to the formation of Bis(2,2,4,4-tetramethyl-2,4-disila-cyclo-butyl)zinc · tmeda 2 . (tmeda)LiCH(SiMe₃)₂ reacts analogously with one equivalent of ZnCl₂ to Bis(trimethylsilyl)methylzinc chloride · tmeda 3 . Lithium methanide or Lithium butanide add to a Si-C bond of 1,1,3,3-tetramethyl-1,3-disila-cyclo-butane, and these acyclic lithium alkanides 4 ( a : R = Me, b : R = n-Bu) yield with zinc(II) chloride the destillable dialkyl zinc compounds Bis(2,2,4,4-tetramethyl-2,4-disilapentyl)- 5 a and Bis(2,2,4,4-tetramethyl-2,4-disila-octyl)zinc 5 b .