The reactivity of an NHC-stabilized silicon(II) hydride

The synthesis and reactivity of an acceptor-free silylene hydride equipped with an N-heterocyclic carbene (NHC) as supporting ligand is reported. The silylene hydride reacts with bis(1,5-cyclooctadiene)nickel(0) to afford a dihydrodisilene complex. Moreover, the reactions of the silylene with alkynes afforded a silole via a [2+2+1] cycloaddition and a 1-alkenyl-1-alkynylsilane via a C-H abstraction depending on the substrate. DFT calculations of their mechanisms suggested the formation of zwitterionic intermediates in these reactions. These are also supported by the product from the reaction of silylene with 1-phenyl-2-trimethylsilylacetylene in the presence of an additional equivalent of NHC.