Insertion of alkynes into Ni-H bonds: Synthesis of novel vinyl nickel(II) and dinuclear vinyl nickel(II) complexes containing a [P,S]-ligand

Reactions of alkynes with nickel hydride complexes bearing a [P, S]-ligand and supported by trimethylphosphine were investigated. Tetracoordinate vinyl nickel(II) complexes 3, 5, and 6 with square-planar geometry were obtained by reacting phenylacetylene, trimethylsilylacetylene, and 1-hexyne with the hydrido nickel complex 1. Reaction of 1,4-bis(trimethylsilylethynyl)benzene with complex 1 proceeds as a monoinsertion and afforded complex 7, while reaction of 1,4-bis(ethynyl)benzene with 1 leads to the dinuclear vinyl nickel(II) complex 8.