Isolation of a hydrogen-bridged bis(silylene) tungsten complex: a snapshot of a transition state for 1,3-hydrogen migration.

A hydrogen-bridged bis(silylene) complex, which can be viewed as a snapshot of a transition state for 1,3-hydrogen migration, was isolated, and its unprecedented WSi2H four-membered-ring structure with a short diagonal Si–Si distance was revealed by X-ray crystallography. NMR studies including determination of the W–Si, Si–Si, and Si–H coupling constants and theoretical calculations suggest that a novel multicenter bond is formed in the WSi2H system, in which the bridging hydrogen takes on a hydridic nature.