Solvated tris(4-morpholinecarbodithioato-S,S') complexes of iron(III) and cobalt(III). Direct comparison of d5 and d6 analogs and study of solvation effects

Abstract

A number of tris(dithiocarbamato)iron(III) and -cobalt(III) solvate complexes have been examined. Inclusion of polar solvent molecules appears to be the common norm in crystals of these complexes. The decomposition points, at which all the solvent suddenly escapes, breaking up the crystal lattices, are well above the boiling points of the particular solvents. The iron(II1) complexes retain the solvent molecules less well, and in many cases, solvent is lost on standing, a fact that may explain a number of the difficulties in earlier attempts at structural analysis. The strong trend to form solvates is the probable cause of anomalous nmr spectra observed in several of the cobalt complexes. Crystal structures of the dichloromethane solvates of the title complexes-were determined from three-dimensional counter data at room temperature. Both compounds crystallize in space group PI, Z = 2. The lattice constants are a = 13.088 (3) 8,, b = 10.693 (1) A, c = 11.499 (1) A, LY = 116.08 (l)', p = 104.97 (l)', and y = 99.49 (2)' for the iron complex and a = 13.079 (1) A, b = 10.682 (1) A, c = 11.493 (1) A, a = 116.03 (l)', (3 = 105.04 (l)', and y = 99.45 (1)' for the cobalt complex. The data were refined by block-diagonal least squares to R = 6.3% (iron) and 4.2% (cobalt). The molecular geometry of the Cos6 in the cobalt is identical with previous cobalt tris(dithio chelate) structures with ((20-4) = 2.27 8, and (SII-CO-SQ) = 76.1O. The values of 2.44 8, and 72.5' for (Fe-S) and (SLi-Fe-S12) in the iron complex are atypical and the linear relationship previously postulated for the magnetic moments and Fe-S bond length in iron tris(dithio chelate) complexes does not seem to be universally applicable. The solvent molecules are orientated so as to minimize electrostatic repulsions with the complex. However, no strong hydrogen bonding interactions exist.