Synthetic routes to mixed-ligand cobalt(III) dithiocarbamato complexes containing imidazole, amine and pyridine donors and the X-ray crystal structure of a cobalt(III) bis(dithiocarbamato) histamine complex

The binuclear cobalt complex [Co-2(Me(2)dtc)(5)](+) reacts with a range of nitrogen donor ligands L' or L '' to form an equimolar mixture of Co(Me(2)dtc)(3) and the mixed-ligand complexes [Co(Me(2)dtc)(2)(L')(2)]+ or [Co(Me(2)dtc)(2)(L '')](+), where (L')(2) is two monodentate ligands and (L '') is one bidentate ligand. The complexes prepared by this route contain the monodentate ligands L' = 1-methyl-imidazole, I -methyl-5-nitro-imidazole and benzimidazole, all of which coordinate to cobalt through an imidazole nitrogen atom. Symmetrical bidentate ligand complexes contain the bisimidazole L '' = 2,2'-bis(4,5-dimethylimidazole), the diamine L '' = 1,2-diaminobenzene and the pyridine donors L '' = 2,2'-bipyridine, 4,4'-dimethyl-2,2'-bipyridine and 1, 1 0-phenanthroline. Two examples of complexes with unsymmetrical bidentate imidazole-amine donors were prepared in which L '' = 4-(2-aminoethyl)imidazole (histamine) and 2-aminomethylbenzimidazole. All new complexes were fully characterised, and the X-ray crystal structure of the histamine complex [Co(Me(2)dtc)(2)(hist)]ClO4 is also reported. (c) 2007 Elsevier Inc. All rights reserved.