The synthesis and crystal structures of new trinuclear and hexanuclear nickel complexes withmetallodithiolate ligands

Two nickel complexes with metallodithiolate ligands, which can be regarded as the active site models of the acetyl coenzyme A synthase, were prepared and structurally characterized by X-ray crystallography. Reactions of Ni(PPh3)(2) Cl-2 with Ni(bme-dach) [bme-dach = N, N'-bis( mercaptoethyl)-1,4-diazacycloheptane] or Ni(bme-dach*) [bmedach* = N, N'-bis(mercaptoethyl)-1,4-diazacyclohexane] in MeCN in the presence of NH4 PF6 resulted in the formation of a trinuclear nickel complex {Ni[Ni(bme-dach)](2)}[PF6-](2) (1) and a hexanuclear nickel complex {Ni-2 [Ni(bme-dach*)](4)}[PF6-](4) (2). The crystal structure of 1.2MeCN shows a square planar geometry of nickel atom that is coordinated by four sulfur atoms of the metallodithiolate ligands Ni(bme-dach). The crystal structure of 2.4MeCN reveals that each of the two nickel atoms is ligated by four sulfur atoms of the metallodithiolate ligands Ni(bme-dach*) to form a square planar coordination sphere.