REACTIVITY OF DINUCLEAR TUNGSTEN CARBONYLS BRIDGED BOTH BY HYDRIDE AND BY BIDENTATE PHOSPHINE-LIGANDS, (MU-H)(MU-PH2P(CH2)NPPH2)W2(CO)7(NO)(N = 1-3)

The ligand substitution of (mu-H)(mu-Ph2P(CH2)nPPh2)W2(CO)7(NO) (n = 1-3, designated as 1, 2 and 3) provides complexes (mu-H)(mu-Ph2P(CH2)nPPh2)W2(CO)6(L)(NO) (L = PhPH2, n = 1-3, designated as 4, 5 and 6: L = nPrNC, n = 1-3, designated as 7, 8 and 9). Michael addition towards several conjugate olefins following the deprotonation of PhPH2 in 4 results in the formation of the complexes (mu-H)(mu-dppm)W2(CO)6(PhPH(CH2CH2X))(NO) (10, X = CN; 11, X = C(O)H; 12, X = C(O)Me). Diastereomers are found in complexes 10-12 and the interconversion of the isomers is established for 10. The isomerization involves the dissociation of PhPH(CH2CH2CN). X-ray crystal structure analyses for complexes (mu-H)(mu-dppm)W2(CO)6(Ph2PH)(NO) (13) and 10 were carried out. 13: orthorhombic, Pbca, Z = 8, a 19.428(5), b 36.100(8), c 12.025(1) angstrom, V 8438 (3)angstrom3, R = 0.041, R(w) = 0.059. 10: triclinic, P1BAR, Z = 4, a 9.883(2), b 20.429(4), c 21.137(3) angstrom, alpha-91.24(1), beta-91.87(1), gamma-99.86(2)-degrees, V 4200(1) angstrom3, R = 0.042, R(w) = 0.044.