The evaluation of singlet-triplet separations for [W-2(mu-H)(mu-Cl)Cl-4(mu-dppm)(2)] and [W-2(mu-H)(2)(mu-O2CC6H5)(2)Cl-2(P(C6H5)(3))(2)] based on P-31 NMR and crystallographic data

The singlet-triplet separations for the edge-sharing bioctahedral (ESBO) complex W-2(mu-H)(mu-Cl)(Cl-4(mu-dppm)(2) .(THF)(3) (II) has been studied by P-31 NMR spectroscopy. The structural characterization of [W-2(mu-H)(2)(mu-O2CC6H5)(2)Cl-2(P(C6H5)(3))(2)] (I) by single-crystal X-ray crystallography has allowed the comparison of the energy of the HOMO-LUMO separation determined using the Fenske-Hall method for a series of ESBO complexes with two hydride bridging atoms, two chloride bridging atoms and the mixed case with a chloride and hydride bridging atom. The complex representing the mixed case, [W-2(mu-H)(mu-Cl)Cl-4(mu-dppm)(2) . (THF)(3)] (II), has been synthesized and the value of -2J determined from variable-temperature P-31 NMR spectroscopy.