HETEROLEPTIC DIORGANOZINC COMPOUNDS OF TH E TYPE (ME3SI)3C-ZN-R

The equimolar reaction of lithium tris(trimethylsilyl)methanide with z inc(II) chloride in a solvent mixture of THF and diethylether yields t richloro-bis([tris(trimethylsilyl)methyl]zincate) . 2THF . Et2O. The a ddition of organyl lithium leads to the formation of heteroleptic orga nyl-[tris(trimethylsilyl)methyl]zinc. No ligand exchange reactions can be observed for these compounds. Due to the steric demand of the tris (trimethylsilyl)methyl substituent these derivatives are monomeric in solution as well as in the solid state. ethylsilyl)methyl-[tris(trimet hylsilyl)methyl]zinc crystallizes in the monoclinic space group P2(1)/ n (a = 910.7(2), b = 1633.0(4), c = 1863.9(4) pm, beta = 94.18(2)-degr ees and Z = 4). The Zn-C-distances are elongated to a value of 197 pm due to the steric demand of both the substituents. The zinc atom is wi th an CZnC angle of 176-degrees nearly linear coordinated. Phenyl-[tri s(trimethylsilyl)methyl]zinc with a melting point of about 24-degrees- C crystallizes upon cooling in a nitrogen stream (P2(1), a = 908.4(3), b = 1489.0(4), c = 1594.5(3) pm, beta = 94.68(2)-degrees and Z = 4). Due to the small size of the phenyl group rather short Zn-C-bond lengt hs of about 193.5 pm are formed.