SYNTHESES AND STEREOCHEMISTRY OF DICOBALT(II) COMPLEXES [CO2(DPPM)(MU-SR)2(SR)2] (DPPM = PH2PCH2PPH2 - R = C6H5, M-C6H4CH3, P-C6H4CH3 AND P-C6H4-TC4H9) AND [CO2(DPPE)(MU-SPH)3(SPH)] (DPPE = PH2PCH2CH2PPH2)

From reactions of Co(dppm)2Cl2 or Co(dppm)Cl2 with thiolate and elemental selenium or sulphur in DMF, the following complexes were prepared in good yields: [Co2(dppm)(mu-SR)2(SR)2] (R = C6H5, 1; m-C6H4CH3, 2; p-C6H4CH3, 3; and p-C6H4-(t)C4H9, 4). Compound 1 crystallizes in two different isomeric crystals, 1A and 1S, containing three stereoisomers of molecular conformations: 1aa, 1sa and 1ss. The two different crystal structures of compound 1 were confirmed by thermal analysis and IR spectra. Compound 2 crystallizes with molecules of type ss. Compound [Co2(dppe)(mu-SPh)3(SPh)] (5) is an asymmetric molecule with one five-coordinate cobalt atom and one four-coordinate cobalt atom. From the EPR spectra and magnetic susceptibility data, it is deduced that there is antiferromagnetic coupling between the two paramagnetic cobalt(II) atoms in compounds 1-5.