Silicon-lead chalcogenides of the types Me4Si2(E)2PbPh2 and Ph2Pb(E)2Si2Me2(E)2PbPh2 (E=S, Se) and related compounds containing tin and antimony

The reaction of a 1:1 mixture of Ph2PbCl2 and ClSiMe2–SiMe2Cl with H2S/NEt3 yielded the mixed silicon–lead sulfide Me4Si2(S)2PbPh2 (1a), a bicyclic silicon lead sulfide, Ph2Pb(S)2Si2Me2(S)2PbPh2 (1b) was obtained by similar treatment of a 2:1 mixture of Ph2PbCl2 and Cl2SiMe–SiMeCl2. The corresponding selenium compounds (2a–b) were obtained by reactions of mixtures of Ph2PbCl2 and methylchlorodisilanes with Li2Se in THF. All products were characterized by multinuclear (1H, 13C, 29Si, 77Se and 207Pb) NMR spectroscopy. The molecular structure of 1a is reported revealing a central five membered ring Si2S2Pb in envelope conformation with one sulfur atom (S1) above the plane defined by the atoms Pb1S2Si2Si1. For comparison, the tin compounds Me4Si2(Se)2SnPh2 (4a), and Ph2Sn(Se)2Si2Me2(Se)2SnPh2 (4b) have also been prepared essentially applying the same procedure as for compounds 2a–b. A plot of δ (207Pb) of 1a–2b versus δ (119Sn) of the corresponding tin compounds 3a–4b exhibits a linear correlation with a slope of 4.11 (±0.17). Attempts to build related cycles containing a Group 15 element led to the isolation of the antimony compounds Me4Si2(E)2SbPh (5a: E=S, 5b: E=Se) starting from ClSiMe2–SiMe2Cl, PhSbCl2 and either H2S/NEt3 or Li2Se.