Synthesis and structure of Co[Tl(SCN) 2] 2 and its derivatives

Abstract

The binuclear mixed-metal tetrathiocyanate complex Co[Tl(SCN) 2] 2 was synthesized and was reacted with certain Lewis bases. It was observed that the Lewis bases (solvents) with a dielectric constant less than 24.3 and a donor number less than 17 do not have any effect on the Lewis acid, that those with a donor number in the range 17–30 form polymeric bridged complexes and that those with a donor number above 30 and a dielectric constant below 36 form cationic-anionic complexes. The complexes were characterized by elemental analysis, conductance measurements, magnetic susceptibility measurements and IR and electronic spectral studies. These investigations indicate that the tetrahydrofuran, dimethylformamide, dimethylsulphoxide, methanol, ethanol and acetone complexes are polymeric bridged complexes, that the triphenylphosphine complex is monomeric and that the pyridine, aniline, nicotinamide, 2,2′-bipyridyl and 1,10-phenanthroline complexes are cationic-anionic. Quantitative softness values E ° n and E ° m indicate that all the ligands prefer to coordinate with cobalt rather than with thallium.