Coordination modes of polydentate ligands. 3. Five-coordinate complexes of cobalt(2+), copper(2+), and nickel(2+) containing a tridentate thioether-alkoxy ligand

Abstract

A study has been made of the application of the dianion of the fluorinated alcohol-thioether 2,2'-[thiobis(methylene)]bis-[ 1,1,1,3,3,3-hexafluoro-2-propanol], [HOC(CF3)2CH2]2S, as a tridentate, dinegative, ligand. Stable, neutral, complexes are formed with Coz+, Ni2+, and Cu2+ from nitrogen-containing coligands, and five-wordination is favored. A complete structural determination has been carried out on the complex Co[OC(CF )2CH2]2S(C5H~N)2. The crystals are monoclinic, space group C2/c, with a = 26.24 (1) A, b = 16.565 (9) A, c = 10.998 (6) A, 0 = 104.50 (4)O, and 2 = 8. The Co2+ ion is five-coordinate in trigonal-bipyramidal geometry, with the alkoxy-thioether ligand adopting a facial configuration, the sulfur atom being in the apical position. These complexes show no tendency to increase the coordination number of the metal to 6 by solvation, an effect attributed to the bulk of the fluorinated alkoxy groups.