SYNTHESIS, STRUCTURE, AND REACTIVITY OF TRISILANES CONTAINING THE 8-(DIMETHYLAMINO)-1-NAPHTHYL GROUP AT THE CENTRAL SILICON ATOM - A NOVEL NICKEL-CATALYZED OR PALLADIUM-CATALYZED DEGRADATION OF TRISILANE TO DISILANE AND SILYLENE SPECIES

Three trisilanes containing the 8-(dimethylamino)-l-naphthyl group on the central silicon atom have been prepared. While X-ray structural analysis and NMR studies reveal that the trisilane skeleton is rather reluctant to pentacoordination, unusual UV and mass spectral features and high reactivity toward a nickel axid a palladium catalyst have been recognized. In the Ni- and Pd-catalyzed reactions, the two terminal silicon atoms in the trisilane couple each other to form the corresponding disilane. The central silicon atom extruded as a reactive silylene species has been trapped with diphenylacetylene in the Pd case to form, after chromatographic workup, a cis/trans mixture of the 4-oxa-3,5-disilacyclopent-1-ene derivative. The X-ray structure of the trans isomer shows the presence of two slightly pentacoordinated silicon atoms.