SYNTHESIS AND CHARACTERIZATION OF DIVALENT LANTHANIDE SELENOLATES AND TELLUROLATES - X-RAY CRYSTAL-STRUCTURES OF YB[SESI(SIME3)3]2(TMEDA)2 AND (EU[TESI(SIME3)3]2(DMPE)2)2(MU-DMPE)

A series of divalent lanthanide chalcogenolates of empirical formula Ln[ESi(SiMe3)3]2(TMEDA)2 (Ln = Yb, Eu, Sm; E = Se, Te; TMEDA = Me2NCH2CH2NMe2) and {Eu[ESi(SiMe3)3]2(DMPE)2}2(mu-DMPE) (E = Se, Te; DMPE = Me2PCH2CH2PMe2) have been prepared by the reaction of Ln[N(SiMe3)2]2(THF)2 (Ln = Yb, Eu, Sm) with HESi(SiMe3)3 (E = Se, Te) in diethyl ether with excess TMEDA or DMPE. Both Yb[SeSi(SiMe3)3]2-(TMEDA)2 and {Eu[ESi(SiMe3)3]2(DMPE)2}2(mu-DMPE) have been structurally characterized by X-ray crystallography. Yb[SeSi(SiMe3)3]2(TMEDA)2 crystallizes at -40-degrees-C from hexanes in the space group P2(1)/c with a = 9.441(2) angstrom, b = 12.311(2) angstrom, c = 23.407(7) angstrom, beta = 96.013(21)degrees, V = 2705.4(11) angstrom3, d(calcd) = 1.30 g cm-3, and Z = 2. {Eu[ESi(SiMe3)3]2(DMPE)2}2(mu-DMPE) crystallizes at -40-degrees-C from hexanes in the space group P1BAR with a = 13.629(2) angstrom, b = 13.696(2) angstrom, c = 17.642(3) angstrom, alpha = 81.715(13)degrees, beta = 78.828(12)degrees, gamma = 89.452(13)degrees, V = 3190.2(12) angstrom3, d(calcd) = 1.33 g cm-3, and Z = 2. On being heated to ca. 200-degrees-C in the solid state, the Yb-TMEDA compounds eliminate E[Si(SiMe3)3]2 to form the corresponding divalent chalcogenides as dark, microcrystalline powders.