SYNTHESES OF TUNGSTEN-SUBSTITUTED OLIGOSILANES

By way of alkali halide elimination, monotungsten- and ditungsten-subs tituted oligosilanes can be obtained. The polarity of the solvent used and the leaving groups at silicon have a strong influence on the synt heses. Heterogeneous reactions (apolar solvent) result in monotungsten compounds, whereas homogeneous conditions (mixture of solvents) short en the reaction time and lead to alpha,omega-ditungstensilanes. Using this modified alkali halide elimination method, the new permethylated silicon-tungsten compounds Cl-(SiMe(2))(n)-Wp and Wp-(SiMe(2))(n)-Wp ( n = 3, 4; Wp = W(CO)(3)cp) were isolated. In addition, the synthesis o f the first perhydrogenated alpha,omega-ditungsten oligosilanes Wp-(Si H2)(n)-Wp (n = 2, 3) is reported. Cyclic silanes with a tungsten subst ituent and further reactive groups in the molecule are obtained by sel ective reaction of the triflate group at silicon.