Model of the SN2 nucleophilic substitution at the Si atom: X-ray structural study of N-(halogenodimethylsilylmethyl) lactams

Abstract

X-ray studies show that Si–O and Si–X (X = I, Br, Cl, F) distances at the pentaco-ordinated Si atom in N-(halogenodimethylsilylmethyl)lactams vary over a wide range [1.749(2)–2.461(8) and 3.734(1)–1.630(7)Å, respectively] in the series X = I → Br → Cl → F; hence these compounds can be regarded as models of intermediate stages of S_N2 substitution at the tetrahedral Si atom.