The Reaction of Tin(II) Halides with Li(THF) 2.5 Ge(SiMe 3 ) 3 : The X-ray Crystal Structure of a New Cyclotetrastannane

Abstract

Reaction of SnCl₂ with two equivalents of Li(THF)_2.5Ge(SiMe₃)₃ in hexane at −78°C gave both red and colorless crystalline products. The latter was identified by m.p and NMR spectra as [(Me₃Si)₃Ge]₂SnCl₂. FAB mass spectra showed that the red crystals contained an Sn₄ cluster and Ge(SiMe₃)₄. An X-ray structure determination on the red crystals was complicated by several types of disorder but the structure was solved with the aid of a new simulated annealing program revealing the product as the heteroleptic cyclotetrastannane, [(Me₃Si)₃GeSnC1]₄. The product crystallized as a complex with two molecules of Ge(SiMe₃)₄ in the F23 (cubic) space group with a = 23.120(7) Å, ρ(ca1c) = 1.35 g-cm⁻³, Z = 4,996 data collected, R = 0.049. Similar reactions of SnX₂, (X = F,I) appeared to result in reduction of the tin.