Thermodynamic hydride donor abilities of [HW(CO)4L]- complexes (L = PPh3, P(OMe)3, CO) and their reactions with [C5Me5Re(PMe3)(NO)(CO)]+.

The thermodynamic hydride donor abilities of HW(CO)(5) (40 kcal/mol), HW(CO)(4)P(OMe(3)) (37 kcal/mol), and HW(CO)(4)(PPh(3)) (36 kcal/mol) have been measured in acetonitrile by either equilibrium or calorimetric methods. The hydride donor abilities of these complexes are compared with other complexes for which similar thermodynamic measurements have been made. HW(CO)(5), HW(CO)(4)P(OMe(3)), and HW(CO)(4)(PPh(3)) all react rapidly with CpRe(PMe(3))(NO)(CO) to form dinuclear intermediates with bridging formyl ligands. These intermediates slowly form [CpRe(PMe(3))(NO)(CHO)] and [W(CO)(4)(L)(CH(3)CN)]. The structure of cis-HW(CO)(4)(PPh(3)) has been determined and has the expected octahedral structure. The hydride ligand bends away from the CO ligand trans to PPh(3) and toward PPh(3).