Synthesis, Crystal Structures, and Properties of S-Bridged Pt(II)-Ni(II) Dinuclear Complexes: Conversion of Square-Planar [Ni(aet)2] to Octahedral Geometry by Forming an S-Bridged Structure with Pt(II) (aet = 2-Aminoethanethiolate)

Abstract

Abstract The reactions of [Ni(aet)2] with [PtCl2(L)] gave a new type of S-bridged dinuclear complexes [Pt(L){Ni(aet)2(H2O)2}]2+ (aet = aminoethanethiolate; L = bpy = 2,2′-bipyridine, phen = 1,10-phenanthroline (5), dmbpy = 4,4′-dimethyl-2,2′-bipyridine). These complexes readily react with L′ to form [M(L){Ni(aet)2(L′)}]2+ (L = bpy, L′ = bpy (3), phen; L = phen, L′ = phen, bpy; L = L′ = dmbpy). A similar reaction of [Ni(aet)2] with [PtCl2(phen)] and phen gave only [Pt(phen){Ni(aet)2(phen)}]2+. The crystal structures of 3 and 5 were determined by X-ray crystallography. The Ni atoms are surrounded by two aet and a bpy or two water molecules to have an approximately octahedral geometry, forming the C2-cis(S)-[Ni(aet)2{bpy or (H2O)2}] unit. The Pt atoms have a square-planar geometry, in which two Cl atoms of the starting [PtCl2(L)] (L = bpy or phen) have been substituted by the two S atoms from the Ni(II) unit. The Pt(II) plane and the Ni(II) equatorial plane are almost coplanar, and the Pt–Ni distance is 3.4987(8) Å (3) and 3.476(4) Å (5). All of the complexes were characterized on the basis of the electronic absorption and infrared spectra and the cyclic voltammetry. The conversion of a square-planar [Ni(aet)2] to an octahedral [Ni(aet)2{(H2O)2 or (L′)}] units was also considered. In the solid state, the water molecule in [Pt(L){Ni(aet)2(H2O)2}]2+ could be readily exchanged by nitrate.