Edge-Sharing Bioctahedral Dimolybdenum(III) molecules with μ-RS Groups. Direct Experimental Evidence for Spin-State Equilibria

Article abstract of DOI:10.1021/ja00311a036

A series of dimolybdenium(III) molecules with edge-sharing bioctahedral structures and general formula (LL)-MoCl2(μ-SR)2MoCl2(LL) have been prepared: namely-1, LL = dto, R = Et; 2, LL = dmpe, R = Et; 3, LL = dtd, R = Et; 4, LL = dto, R = Ph; 5, LL =dmpe, R = Ph; 6, LL = dtd, R = Ph (dto = EtSCH2CH2SEt; dtd = PrSCH2CH2SPr; dmpe = Me2PCH2CH2PMe2).Principal methods of preparation are (a) Mo2Cl8^4- + 2LL + RSSR and (b) Mo2Cl4(LL)2 + RssR.Compounds 1 and 2 have been structurally characterized by X-ray crystallography.In each case there is a central, planar (LL)Mo(μ-SR)2Mo(LL) unit with chlorine atoms above and below this plane on each molybdenum atom.Compound 1 forms crystals in space group C2/c with a = 18.114 (4) Angstroem, b = 9.925 (1) Angstroem, c = 16.403 (4) Angstroem, β = 97.76 (2) deg, Z = 4.The Mo-Mo distance is 2.682 (1) Angstroem.Compound 2 forms crystals in space group Pnmn with a = 12.835 (3) Angstroem, b = 15.705 (5) Angstroem, c = 9.046 (2) Angstroem, Z = 2.The Mo-Mo distance is 2.712 (3) Angstroem.Compounds 1,2, and 4 have been characterized magnetically and exhibit temperature-dependent magnetic properties consistent with the thermal population of an excited triplet state based on the δ^*δ configuration.