Protonation of diphosphazane ligand-bridged derivatives of diruthenium nonacarbonyl by protic acids with co-ordinating and non-co-ordinating conjugate bases
Abstract
Protonation of the diphosphazane ligand-bridged derivatives [Ru2(µ-CO)(CO)4{µ-(RO)2PN(Et)P(OR)2}2](R = Me or Pri) by HBF4 or HPF6 leads to the formation of the cationic hydrido products [Ru2H(CO)5{µ-(RO)2PN(Et)P(OR)2}2]+ in which the hydride ligand is co-ordinated terminally. On the other hand protonation of these species with strong protic acids HA having conjugate bases A– with co-ordinating properties [A–= Cl–, Br–, NO3–, FB(O)OH– or CF3CO2–] gives rise to products of the type [Ru2A(CO)5{µ-(RO)2PN(Et)P(OR)2}2]+ and/or [Ru2(µ-A)(CO)4{µ-(RO)2PN(Et)P(OR)2}2]+. Weak acids HA (A–= SPh– or HCO3–) also afford these types of products but the presence of a strong acid such as HPF6 is necessary. The structures of two of the products [Ru2{µ-OB(F)OH}(CO)4{µ-(PriO)2PN(Et)P(OPri)2}2]BF4 and [Ru2(µ-SPh)(CO)4{µ-(MeO)2PN(Et)P(OMe)2}2]PF6 have been established by X-ray crystallography and are discussed as is the fluxional behaviour of the hydrido species [Ru2H(CO)5{µ-(RO)2PN(Et)P(OR)2}2]+.