Preparation and Characterization of Ruthenium(II) Monophosphaferrocene Complexes. Reactivity, Dynamic Solution Behavior, and X-ray Structure of [RuH2(η2-H2)(PCy3)2(2-phenyl-3,4-dimethylphosphaferrocene)]

The bis(dihydrogen) complex RuH2(H2)2(PCy3)2 (1) reacts with 2-phenyl-3,4-dimethylphosphaferrocene (L 1) to give RuH2(H2)(PCy3)2(L 1) (2). This dihydride−dihydrogen complex has been characterized by X-ray crystallography and variable-temperature 1H and 31P NMR spectroscopy. The exchange between the dihydrogen ligand and the two hydrides is characterized by a ΔG ⧧ of 46.2 kJ/mol at 263 K. H/D exchange is readily observed when heating a C7D8 solution of 2 (J H-D = 30 Hz). The H2 ligand in 2 can be displaced by ethylene or carbon monoxide leading to the corresponding ethylene or carbonyl complexes. The reaction of 1 with 2 equiv of 3,4-dimethylphosphaferrocene (L 2) yields the dihydride complex RuH2(PCy3)2(L 2)2 (5).