Chemistry of highly electrophilic binuclear cations.: 3.: Reactivity of [W2(η5-C5H5)2(μ-CO)(CO)2(μ-Ph2PCH2PPh2)][B3,5-C6H3(CF3)2}4]2 toward small donor molecules

Reaction of the unsaturated tricarbonyl complex [W2Cp2(mu-CO)(CO)(2)(mu-dppm)](BAr'(4))(2) with HSPh leads to the thiolate-bridged complex [W2Cp2(mu-SPh)(mu-CO)(CO)(2)(mu-dppm)](BAr'(4)), which is obtained as a mixture of two isomers. This reaction proceeds faster in the presence of a base (1,8-diazabicyclo[5.4.0]undec-7-ene, DBU), as expected. The title compound also reacts at room temperature with stoichiometric amounts of phosphines (HPRR2)-R-1 (R-1 = R-2 = Ph; R-1 = H, R-2 = Cy) to give the corresponding phosphide hydride derivatives [W2Cp2(mu-H)(mu-(PRR2)-R-1 )(CO)(2)(mu-dppm)](BAr'(4))(2), which display a trans relative geometry of their phosphide and diphosphine ligands. Deprotonation of these hydride complexes with DBU gives the cis phosphide compounds [W2Cp2(mu-(PRR2)-R-1)(CO)(2)(mu-dppm)](BAr'(4)), through an unexpected reduction and dehydrogenation/isomerization pathway. This overall deprotonation process is not reversible, and treatment of the latter compound with (HBF4OEt2)-O-. gives the hydride isomer cis-[W2Cp2(mu-H)(mu-(PRR2)-R-1)(CO)(2)(mu-dppm)](BAr'(4))(BF4), which displays a strong hydrogen bond interaction between the bridging hydride ligand and the external BF4- anion. Treatment of the title compound with N2CHSiMe3 or HC=C(p-tol) leads to dicarbonyls [W2Cp2{mu-kappa(1)-N2CH(SiMe3)}(CO)(2)(mu-dppm)](BAr'(4))(2) or [W2Cp2{mu-eta(2):eta(2)-HCC(p-tol)}(CO)(2)(mu-dppm)](BAr'(4))(2) (two isomers), displaying four-electron-donor diazoalkane or alkyne bridging ligands.