Tris(triisopropylsilyl)silane and the Generation of Bis(triisopropylsilyl)silylene

Tris(triisopropylsilyl)silane (iPr 3 Si) 3 SiH has been synthesized and studied by X-ray and neutron diffraction. It possesses an unusual structure in which the four silicon atoms are nearly coplanar, ∠Si−Si−Si = 118.41(5)°. The Si−H distance is found to have a normal value of 1.506(2) Å. Thermal and room-temperature photochemical decomposition of (iPr 3 Si) 3 SiH leads to the elimination of iPr 3 SiH and the generation of bis(triisopropylsilyl)silylene, [(iPr 3 Si) 2 Si:]. Reactions of (iPr 3 Si) 2 Si: include precedented insertions into H−Si bonds and addition to the π-bonds of olefins, alkynes, and dienes. Despite theoretical predictions of a triplet ground state for [(iPr 3 Si) 2 Si:], stereospecific addition to cis- and trans- 2-butene was observed.