Synthesis of hexanuclear molybdenum clusters containing phosphine oxide ligands

摘要

We report the direct preparation of two new octahedral hexanuclear molybdenum cluster complexes containing phosphine oxide ligands, namely [Mo_6(mu_3Cl)_8{OP(n-Pr)_3}_2Cl_4] and [Mo(mu_3-Cl_8)(OPEt_3)_2Cl_4], from Mo_6Cl_(12) and the corresponding phosphine oxide ligands. Both of these complexes were characterized by NMR and IR spectroscopies, cyclic voltammetry and elemental analysis. Further, a single-crystal X-ray structure determination of [Mo_6(mu_3-Cl)_8{OP(n-Pr)_3}_2Cl_4] was obtained: [Mo_6(mu_3-Cl)_8{OP(n-Pr)_3}_2Cl_4] crystallizes in the monoclinic space group, P2_1 with a = 10.0685(16) A, b = 15.617 (2) A, c = 15.693(3) A, beta = 91.799(5) deg, and R1 = 0.0288. A trans arrangement of the phosphine oxide ligands was observed, where both ligands are bonded to the molybdenum cluster through the oxygen atoms. We also investigated the reaction [Mo_6(mu_3-Cl)_8{P(n-Pr)_3}_2Cl_4] witha variety of oxidizing agents and phosphine oxide, yielding [Mo_6(mu_3-Cl)_8{OP(n-Pr)_3}_2Cl_4].