Syntheses, structures and properties of tri-n-butylphosphine cobalt complexes containing o-benzenedithiolate ligands in unusual co-ordination modes
Abstract
The complex [Co3(bdt)3(PBun3)3]1(H2bdt = benzene-1,2-dithiol) was obtained by the reaction of CoCl2, Na2bdt and PBun3 in 1:1:2 molar ratio in methanol. It crystallizes in triclinic space group P with a= 13.694(4), b= 18.460(4), c= 13.656(4)Å, α= 100.69(2), β= 108.68(2), γ= 85.06(2)°, Z= 2, from 6366 reflections with I > 3σ(I), 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 [PHBun3][Co(bdt)2(PBun3)]2, which crystallizes in triclinic space group P with a= 10.800(3), b= 13.533(4), c= 15.342(2)Å, α= 96.37(2), β= 108.57(2), γ= 97.02(2)°, Z= 2, from 3801 reflections with I > 3σ(I), R(R′)= 0.086 (0.088). The Co atom is in a square-pyramidal co-ordination environment with P in the axial position. The PBun3 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.