Synthetic, spectral, electrochemical and structural aspects of some Ru(II) arene complexes with some novel bridging ligands

Reactions of chloro-bridged dimeric Ru(II) complexes [{Ru(η6-arene)Cl2}2] with bridging ligands 1,4-dicyanamidobenzene, N,N′-dicyano 4-4′-diaminobiphenyl, 2,5-dichloro-1,4-dicyanamidobenzene and 2,5-dimethyl-1,4-dicyanamidobenzene (referred hereafter as dcdH2, bpH2, ddcl and dmcd) in dicloromethane at room temperature gave binuclear complexes with the general formulation [{Ru(η6-arene)Cl2}2(μ-L)]. However, reactions of these bridging ligands with the complexes [Ru(η6-arene)(P)Cl2](η6-arene=benzene or p-cymene; P=PPh3, PEt3 or MePPri2) in methanol, in presence of NH4PF6, gave cationic arene complexes [{Ru(η6-arene)(P)Cl}2(L)]2+ (L=dcdH2, bpH2, dmcd or ddcl). The reaction products have been characterized by physico-chemical methods viz., elemental analyses, IR, 1H-, 13C-, 31P-NMR, electronic and FAB mass spectra. The complexes under study are highly stable at room temperature. However, their solutions in coordinating solvents like acetonitrile or dimthylsulfoxide undergo substitution reactions to give substitutional products with the formulation RuCl2(sol)4. It has been confirmed by single crystal X-ray diffraction studies.