Synthesis and Characterization of [(NHC)Ni(styrene)(2)] Complexes: Isolation of Monocarbene Nickel Complexes and Benchmarking of %V-Bur in (NHC)Ni-pi Systems

The investigation of the stereoelectronic influence of N-aryl substituted NHC ligands on Ni(0) is reported. The structural analysis of a family of [(NHC)Ni(styrene)(2)] complexes are correlated to known literature parameters (TEP and %V-Bur). The analysis involved NMR spectroscopic techniques and X-ray crystallography analysis of the isolated [(NHC)Ni(styrene)(2)] complexes. The synthesis and characterization of this user-friendly and easy accessible Ni(0) precatalysts can be realized in a two-step synthesis starting from deprotonation of the imidazolium salt followed by direct coordination onto nickel in the presence of excess styrene.