4,4′-Dimethyl-2,2′-bithiazole: Potent co-former in coordination compounds

Abstract

The ability of the 4,4′-dimethyl-2,2′-bithiazole (4dm2bt) ligand to act as a second-sphere co-former in coordination compounds is investigated through the preparation of a series of iron complexes. In this regard, the self-assembly process of FeCl3·6H2O or FeCl3 in the presence of several N-N′-chelating ligands and 4dm2bt was investigated. The complexes [Fe(bipy)(H2O)Cl3][4dm2bt] (1), [Fe(bipy)(CH3OH)Cl3][4dm2bt]0.5 (2), {[Fe(4,4′-dmbipy)3][FeCl4]2}[4dm2bt]0.5 (3), {[Fe(phen)2Cl2][FeCl4]}[4dm2bt]0.5 (4) and {[Fe(5-mephen)2Cl2][FeCl4]}[4dm2bt]0.5 (5), which contain the 4dm2bt co-former, were prepared (bipy=2,2′-bipyridine, 4,4′-dmbipy=4,4′-dimethyl-2,2′-bipyridine, phen=1,10-phenanthroline, 5-mephen=5-methyl-1,10-phenanthroline). The driving forces for the presence of 4dm2bt as a second-sphere co-former ligand are not only several types of non-covalent interactions with the first-sphere coordination ligands or counter anions, but also its low coordination ability for participating as a primary ligand in comparison with the N-N′-chelating ligands used.