Yttrium and lanthanum silyloxide complexes

Reaction of (M(N(SiMe{sub 3}){sub 2}){sub 3}) (M = Y, La) with 3 equiv of Ph{sub 3}SiOH in toluene gave high yields of (M(Oiph{sub 3}){sub 3}){sub n}. The homoleptic tris-((triphenylsilyl)oxy)yttrium and -lanthanum complexes could be converted nearly quantitatively to monomeric Lewis base adducts, (M(OSiPh{sub 3}){sub 3}L{sub n}){center dot}xL (M = Y, La, L = THF, N = 3, X = 1; L = pyridine, n = 3, x = 0; L = OP({sup n}Bu){sub 3}, n = 2, x = 0) by the addition of tetrahydrofuran, pyridine, or 2 equiv of OP({sup n}Bu){sub 3}, respectively. Hydrogen-1 NMR studies on (M(OSiPh{sub 3}){sub 3}(THF){sub 3}){center dot}THF (M = Y, La) and (Y(OSiMe{sub 2}{sup t}Bu){sub 3}(THF){sub 3}) demonstrated that these complexes are kinetically labile on the NMR time scale with respect to exchange with free, added ligand. Low-temperature NMR studies implicated a dissociative mechanism for this process. Phosphorus-31 NMR studies in (Y(OSiPh{sub 3}){sub 3}(OP({sup n}Bu){sub 3}){sub 2}) demonstrated that this complex participates in an exchange reaction between free and coordinated phosphine oxide via an associative mechanism. Anionic tetrakis((triphenylsilyl)oxy)yttrium complexes, (K ({eta}{sup 2}-DME){sub 3}({eta}{sup 1}-DME))(Y(OSiPh{sub 3}){sub 4}({eta}{sup 2}-DME)) and (K(18-crown-6))(Y(OSiPh{sub 3}){sub 4}), were formed by reaction of (Y(OSiPh{sub 3}){sub 3}){sub n} with 1 equiv of the corresponding potassium silyloxide reagent in dimethoxyethane or toluene, respectively. Single-crystal X-ray data are available for five compounds. 26 refs., 7 figs., 13 tabs.