Imidazoline-2-ylidene metal complexes with pendant ferrocenyl substituents

Imidazolium and benzimidazolium salts with ferrocenylated alkyl side chains are prepared as progenitors of N-[(ferrocenyl)alkyl](benz)imidazoline-2-ylidene carbenes, which form metal complexes of W(0), Pd(II), and Hg(II). X-ray structures and other spectroscopic properties show that these carbene precursors and complexes are analogous to published non-ferrocenylated complexes with regard to the coordination sphere at the metal, but different in terms of steric protection of the central metal by the bulky ferrocenyl substituents and in terms of distinguishable redox potentials of the ferrocene/ferrocenium couple. (C) 1998 Elsevier Science S.A.