1,3-Disilabicyclo[1.1.0]butane and η2-Silene Nickel Complex Derived from a Bromosilene.

The reactivity of halogen-substituted silenes (silicon-carbon doubly bonded compounds) is not well understood relative to alkenyl halides. Herein, we report the reductive dimerization and complexation of a stable bromosilene (1). The reaction of 1 with an equimolar amount of KC8 furnished a 1,3-disilabicyclo[1.1.0]butane (trans-3) featuring a remarkably short bridgehead Si-Si bond [2.204(1) Å] and a very wide Si-Si-Cexocyclic angle of 173.0(1)°. Bulky alkyl groups on the bridgehead silicon atoms and less steric hindrance at the bridging carbon atoms lead to the short bridgehead bond. Bromosilene 1 reacted with Ni(PMe3)4 to afford the corresponding η2-bromosilene nickel complex (4) as a minor product. Complex 4 exhibits a twisted square planar structure in the solid state. Structural and spectroscopic properties of 4 indicate considerable metallacyclic character.