ALKYL-SUBSTITUTED, SILYL-SUBSTITUTED, AND GERMYL-SUBSTITUTED THIOLATE, SELENOLATE, AND TELLUROLATE DERIVATIVES AND INTERCONVERSION OF SILYL SPECIES BY CHALCOGEN METATHESIS

The preparation of a series of chalcogenolate species (sol)nLiEY(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)3LiC(SiMe3)3, (THF)3LiSi(SiMe3)3, or (THF)3LiGe(SiMe3)3 is reported. Two derivatives, (THF)2LiSeSi(SiMe3)3 and (THF)LiSSi(SiMe3)3, are more conveniently prepared by novel chalcogen metathesis reactions whereby tellurium is displaced from (THF)2LiTeSi(SiMe3)3 by either Se or S in THF at -55-degrees-C. Protonation of the chalcogenolate anions leads to the stable chalcogenols, HEY(SiMe3)3, which have been fully characterized. In methyl isobutyl ketone (MIBK), the pK(a) values of HTeC(SiMe3)3, HTeSi(SiMe3)3, HTeGe(SiMe3)3, HSeC(SiMe3)3, HSeSi(SiMe3)3, and HSSi(SiMe3)3 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(SiMe3)3, prepared from (THF)Li[N(SiMe3)2] and HTeSi(SiMe3)3, is also described; it crystallizes in the triclinic space group P1BAR with a = 9.083(4) angstrom, b = 11.181(4) angstrom, c = 12.053(8) angstrom, alpha = 93.16(4)degrees, beta = 104.68(5)degrees, gamma = 96.63-degrees, R = 0.0300, and R(w) = 0.0372.