REACTIONS OF THE UNSATURATED SPECIES (ETA-C5ME5)NI-W(CO)3(ETA-C5H5) AND OF ITS METHYLENE DERIVATIVE (ETA-C5ME5)NI(MU-CO)(MU-CH2)W(CO)2(ETA-C5H5) WITH 2-ELECTRON DONORS

The unsaturated complex (eta-C5Me5)Ni-W(CO)3(eta-C5H5) reacts with two-electron donor ligands or their precursors to afford compounds of generic formula (eta-C5Me5)Ni(mu-CO)(mu-L)W(CO)L'(eta-C5H5) (L = CO; L' = CO, PMe3, PMe2Ph, P(OMe)3, PPh2Cl, PPh2H. L = (t)BuNC, CH2; L' = CO). The structure of the mu-CH2 species (eta-C5Me5)Ni(mu-CO)(mu-CH2)W(CO)2(eta-C5H5) (2), which has been communicated (Chetcuti, M. J.; Grant, B. E.; Fanwick, P. E. Organometallics 1990, 9, 1345), has the same molecular geometry as that adopted by most of the other complexes described and is discussed in more depth here. Complex 2 crystallizes in the triclinic space group P1BAR, with angstrom = 8.518 (2) angstrom, b = 10.280 (1) angstrom, c = 10.719 (1) angstrom, alpha = 89.26 (1)-degrees, beta = 87.24 (1)-degrees, gamma = 79.18 (1)-degrees, V = 920.9 (4) angstrom3, Z = 2, and was refined to R = 0.039, R(w) = 0.053. All complexes exhibit dynamic behavior on the NMR time scale that can be rationalized in light of their observed structures. The phosphine ligands PMe3 and PPh2H displace a carbonyl ligand in (eta-C5Me5)Ni(mu-CO)(A-CH2)W(CO)2(eta-C5H5) to afford cis and trans isomers of the phosphine derivatives (eta-C5Me5)Ni(mu-CO)(mu-CH2)W(CO)L(eta-C5H5) (L = PMe3, PPh2H). The reaction of (eta-C5Me5)Ni-W-(CO)3(eta-C5H5) with PPh2Cl proceeds to give the initial phosphine adduct (eta-C5Me5)Ni(mu-CO)2W(CO)(PPh2Cl)(eta-C5H5). Oxidative addition then ensues to afford the cis species (eta-C5Me5)Ni(mu-CO)(mu-PPh2)W(CO)Cl(eta-C5H5), which subsequently equilibrates with the trans isomer. PPh2H is believed to behave similarly, but oxidative addition products are not isolable here. The behavior of the related saturated cyclopentadienylnickel complexes (eta-C5H5)(OC)Ni-W(CO)3(eta-C5H4R) (R = H, Me) toward PMe3, PPh2H, and (t)BuNC is discussed. The syntheses of (eta-C5Me5)Ni(mu-CO)2Mo(CO)(PPh2H)(eta-C5H4Me) (Ni-Mo) and of (eta-C5H5)Ni(mu-(t)BuNC)(mu-CO)MO(CO)2(eta-C5H4Me) (Ni-Mo) are also described.