Synthesis and bonding in platinum(II) complexes with cyclometalated carbene and isoelectronic bis(phosphino)metallocene ligands

Four cycloplatinated complexes of the type [Pt(C"C*){M(eta 5-C5H4PPh2)2-kappa 2P,P'}][PF6]n (M = Fe, n =1; M = Co, n = 2), where C"C* is 2-(3-methylimidazol-2- ylidene-1-yl-kappa C2)phenyl-kappa C1 and similar cyclometalated ligands bearing an additional aromatic ring and phenyl substituents at the imidazol-2-ylidene unit, were prepared and structurally characterized by spectroscopic methods (NMR and ESI MS), elemental analysis, cyclic voltammetry and DFT calculations. Experimental structural parameters and DFT calculations consistently indicate differentiation of the Pt-bound phosphine groups due to unlike trans influence of the phenyl and carbene donor moieties at the cyclometalated ligand in these compounds