Optically active sulfur-bridged Co(III)-M(II) (M=Pd, Pt) dinuclear complexes with square-planar [M(mu-S)(2)(bpy)] (bpy=2,2 '-bipyridine) frameworks derived from octahedral bidentate sulfur-donating Co(III) metalloligands

摘要

The reactions of the optically active octahedral mononuclear complex, trans (N)-[Co(D-pen)(2)](-) (D-pen = D-penicillaminate), with [PdCl2(bpy)] (bpy = 2,2'-bipyridine) and [PtCl2(bpy)] stereoselectively gave the S-bridged dinuclear complexes, [Pd(bpy){Co(D-pen)(2)}](+) (1a) and [Pt(bpy){Co(D-pen)(2)}](+) (1b), respectively. A similar optically active S-bridged dinuclear complex, Delta-[Pt(bpy){Co(aet)(2)(R-pn)}](3+) (2b; aet = 2-aminoethanethiolate, pn = 1,2-propanediamine), was also obtained by the substitution reaction of DeltaDelta-[Ni{Co(aet)(2)(R-pn)}(2)](4+) With [PtCl2(bpy)]. The crystal structures of la, 1b, and 2b were determined by X-ray crystallography, and compared with that of the previously reported Delta-[Pd(bpy){Co(aet)(2)(R-pn)}](3+) (2a). The Co(111) equatorial planes and the PdN2S2 or PtN2S2 square planes in the la and 1b are almost coplanar, while those in 2a and 2b are somewhat bent from each other. In addition, the distortions from the square planes to tetrahedrons in 2a and 2b are more pronounced than those in 1a and 1b. Furthermore, all of the bridging S atoms in 1a and 1b are stereoselectively unified to the S configuration, in contrast to those in 2a and 2b with the R configuration. These reflect the differences of the optically active Co(III) units in these complexes. The electronic absorption, CD, and C-13 NMR spectral behaviors of these complexes are also discussed in relation to their crystal structures. (C) 2003 Elsevier Science Ltd. All rights reserved. [References: 18]