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, angle Si-Si-Si = 118.41(5)degrees. The Si-H distance is found to have a normal value of 1.506(2) Angstrom. 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 pi-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.