Alkyl-, silyl-, and germyl-substituted thiolate, selenolate, and tellurolate derivatives and interconversion of silyl species by chalcogen metathesis (original) (raw)

1993, Journal of the American Chemical Society

The preparation of a series of chalcogenolate species (sol),LiEY(SiMe3)3 (sol = THF, n = 1,2; sol = DME, n = 1; E = S, Se, Te; Y = C, Si, Ge) by direct insertion of elemental E into Li-Y bonds of (THF),LiC(SiMe,),, (THF),LiSi(SiMe&, or (THF),LiGe(SiMe& is reported. Two derivatives, (THF)zLiSeSi(SiMe& and (THF)-LiSSi(SiMe3),, are more conveniently prepared by novel chalcogen metathesis reactions whereby tellurium is displaced from (THF)zLiTeSi(SiMe& by either Se or S in THF at-55 OC. Protonation of the chalcogenolate anions leads to the stable chalcogenols, HEY(SiMe3)3, which have been fully characterized. In methyl isobutyl ketone (MIBK), the pKa values of HTeC(SiMe&, HTeSi(SiMe3)3, HTeGe(SiMe&, HSeC(SiMe&, HSeSi(SiMe&, and HSSi(SiMes), are determined to be 9.3, 7.3, 7.4, 10.8, 8.3, and 10.7, respectively. The X-ray structure of the mono-THF adduct (THF)LiTeSi(SiMe&, prepared from (THF)Li[N(SiMe&] and HTeSi(SiMe&, is also described; it crystallizes in the triclinic space group Pi with a = 9.083(4) A, b = 11.181(4) A, c = 12.053(8) A, a = 93.16(4)O, 0 = 104.68(5)O,