Comparative structural description of five arene ruthenium(II) complexes ofN,N-bidentate Schiff base ligands to related complexes from literature

A series of new half-sandwich Ru(II) complex salts of the general formula [(eta(6)-arene)RuX(L)]PF6(where arene = p-cymene, X = Br and ligandL(1) = N-tert-butyl-N-(pyridyl methylene) amine (complex1), ligandL(2) = N-isopropyl-2-pyridine carbaldimine (complex2), ligandL(3) = (2,5-dimethyl-phenyl)-pyridin-2-yl methylene amine (complex3), ligandL(4) = (3,5-dimethyl-phenyl)-pyridin-2-yl methylene (complex4) and arene = C6H6, X = I, ligandL(5) = (4-bromo-phenyl)-pyridin-2-yl methylene (complex5) have been synthesized by reacting the ruthenium arene precursors [(eta(6)-arene)Ru(mu-X)X](2)withN,N-bidentate ligands in a 1:2 ratio. Full characterization of the complexes was accomplished by physicochemical and spectroscopic methods and X-ray structures of all the complexes1-5. The crystal structures reveal that the ruthenium centers in1-5are coordinated to theN,N-bidentate ligand in a bidentate manner, to the respective halide, and to the arene ring to give a pseudo-tetrahedral geometry around them. The whole arrangement is referred to as the three-legged piano stool, in which theN,N-bidentate ligand and the halide (Br or I) serve as the base occupying three coordination sites, while the arene ring serves as the apex of the stool and occupy the remaining coordination sites.