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).

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 C-2-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(ll) equatorial plane are almost coplanar, and the Pt-Ni distance is 3.4987(8) Angstrom (3) and 3.476(4) Angstrom (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.