Thermodynamic Studies of HRh(depx)2 and [(H)2Rh(depx)2](CF3SO3): Relationships between Five-Coordinate Monohydrides and Six-Coordinate Dihydrides
| Autor: | Daniel L. DuBois, James W. Raebiger |
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| Rok vydání: | 2004 |
| Předmět: | |
| Zdroj: | Organometallics. 24:110-118 |
| ISSN: | 1520-6041 0276-7333 |
| Popis: | Four new rhodium complexes, [Rh(depx)2](CF3SO3), [(H)2Rh(depx)2](CF3SO3), [HRh(depx)2(CH3CN)](CF3SO3)2, and HRh(depx)2 (where depx = α,α‘-bis(diethylphosphino)xylene), have been synthesized and characterized. The pKa values of [(H)2Rh(depx)2]+ (30.6 ± 0.3) and [HRh(depx)2(CH3CN)]2+ (11.5 ± 0.4) in acetonitrile were determined by equilibrium reactions with appropriate bases. The hydride donor ability of [(H)2Rh(depx)2]+ (71.6 ± 1.0 kcal/mol) was determined by the heterolytic cleavage of hydrogen by [HRh(depx)2(CH3CN)]2+ to form [(H)2Rh(depx)2]+ in the presence of thioacetamide or benzamide. These equilibrium measurements, the half-wave potentials for the Rh(+1/0) and Rh(0/−1) couples of [Rh(depx)2]+, and the reversible one-electron oxidation of HRh(depx)2 (all measured at 22 ± 1.5 °C) were used to establish nine heterolytic and homolytic bond-dissociation free energies in acetonitrile. From these relationships, and those established previously for analogous cobalt and platinum complexes, we conclude that t... |
| Databáze: | OpenAIRE |
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