Chemistry of Highly Electrophilic Binuclear Cations. 3. Reactivity of [W2(η5-C5H5)2(μ-CO)(CO)2(μ-Ph2PCH2PPh2)][B{3,5-C6H3(CF3)2}4]2toward Small Donor Molecules

Reaction of the unsaturated tricarbonyl complex [W 2 Cp 2 (μ-CO)(CO) 2 (μ-dppm)](BAr‘ 4 ) 2 with HSPh leads to the thiolate-bridged complex [W 2 Cp 2 (μ-SPh)(μ-CO)(CO) 2 (μ-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 HPR 1 R 2 (R 1 = R 2 = Ph; R 1 = H, R 2 = Cy) to give the corresponding phosphide hydride derivatives [W 2 Cp 2 (μ-H)(μ-PR 1 R 2 )(CO) 2 (μ-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 [W 2 Cp 2 (μ-PR 1 R 2 )(CO) 2 (μ-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 HBF 4 ·OEt 2 gives the hydride isomer cis -[W 2 Cp 2 (μ-H)(μ-PR 1 R 2 )(CO) 2 (μ-dppm)](BAr‘ 4 )(BF 4 ), which displays a strong hydrogen bond interaction between the bridging hydride ligand and the external BF 4 - anion. Treatment of the title compound with N 2 CHSiMe 3 or HC⋮C(p-tol) leads to dicarbonyls [W 2 Cp 2 {μ-κ 1 -N 2 CH(SiMe 3 )}(CO) 2 (μ-dppm)](BAr‘ 4 ) 2 or [W 2 Cp 2 {μ-η 2:η 2 -HCC(p-tol)}(CO) 2 (μ-dppm)](BAr‘ 4 ) 2 (two isomers), displaying four-electron-donor diazoalkane or alkyne bridging ligands.