SYNTHESES, STRUCTURES AND PROPERTIES OF TRI-N-BUTYLPHOSPHINE COBALT COMPLEXES CONTAINING O-BENZENEDITHIOLATE LIGANDS IN UNUSUAL COORDINATION MODES

The complex [Co3(bdt)3(PBu(n)3)3] 1 (H2bdt = benzene-1,2-dithiol) was obtained by the reaction of CoCl2, Na2bdt and PBu(n)3 in 1:1:2 molar ratio in methanol. It crystallizes in triclinic space group P1BAR with a = 13.694(4), b = 18.460(4), c = 13.656(4) angstrom, alpha = 100.69(2), beta = 108.68(2), gamma = 85.06(2)-degrees, Z = 2, from 6366 reflections with \ > 3-sigma(\), final R(R') = 0.059 (0.066). The Co3 atoms form an isosceles triangle with rather short Co-Co bonds. The bdt ligands either bridge between two Co atoms or strongly chelate terminally to one Co atom and simultaneously bridge weakly to the others. Restricted air oxidation of 1 results in the isolation of [PHBu(n)3][Co(bdt)2(PBu(n)3)] 2, which crystallizes in triclinic space group P1BAR with a = 10.800(3), b = 13.533(4), c = 15.342(2) angstrom, alpha = 96.37(2), beta = 108.57(2), gamma = 97.02(2)-degrees, Z = 2, from 3801 reflections with \ > 3-sigma(\), R(R') = 0.086 (0.088). The Co atom is in a square-pyramidal co-ordination environment with P in the axial position. The PBu(n)3 group dissociates easily in dimethyl sulphoxide yielding paramagnetic [Co(bdt)2]- 3 with square-planar cobalt co-ordination. Proton NMR data are discussed and cyclic voltammetry data reported.