Synthesis and Characterization of 14-Electron Cyclopentadienyl Chromium(II) Complexes Containing a Heterocyclic Carbene Ligand

Abstract

Chromocene reacts with 1,3-dimesitylimidazolium chloride in THF to yield cyclopentadiene and CpCrCl(1,3-dimesitylimidazolin-2-ylidene) (1), which contains an N,N-heterocyclic carbene ligand. This new complex is a relatively rare example of a CpCr(II) complex containing four unpaired electrons. The reaction of 1 with phenylmagnesium bromide yields CpCrPh(1,3-dimesitylimidazolin-2-ylidene) (2). An X-ray crystallographic investigation of 2 reveals a two-legged piano stool structure with a planar central Cr atom.