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 [Co2(Me2dtc)5]+ reacts with a range of nitrogen donor ligands L′ or L″ to form an equimolar mixture of Co(Me2dtc)3 and the mixed-ligand complexes [Co(Me2dtc)2(L′)2]+ or [Co(Me2dtc)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, 1-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 1,10-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(Me2dtc)2(hist)]ClO4 is also reported.