Reactions of O(SiMe3)2(1) and S(SiMe3)2(2) with TiCl4 and SnCl4 are described. For (1), Si–O cleavage and release of SiMe3Cl, as monitored by 1H n.m.r. spectroscopy, occurs only in the case of TiCl4 to give [Me3SiO-(Cl)TiO]n. Trichloromethylstannane is the major reaction product with SnCl4. With (2), TiCl4 gives monomeric complexes TiCl2S·2L (L = MeCN) and TiCl2S·3L [L = MeCN or tetrahydrofuran (thf)] following solvation of the polymeric (Cl2TiS)n formed initially. A six-co-ordinate formulation is proposed based on spectral data. The corresponding (Cl2SnS)n formed with SnCl4 does not give similar lattice degradation with strong donors. The lower halides MCl3·3thf (M = Ti, V, or Cl) react with (2) only to give SiMe3Cl and polymeric complexes MCl(S)·nthf (M = Ti or Cr) and VClS4.