The bis(dihydrogen) complex RuH2(H-2)(2)(PCy3)(2) (1) reacts with 2-phenyl-3,4-dimethylphosphaferrocene (L-1) to give RuH2(H-2)(PCy3)(2)(L-1) (2) This dihydride-dihydrogen complex has been characterized by X-ray crystallography and variable-temperature H-1 and P-31 NMR spectroscopy. The exchange between the dihydrogen ligand and the two hydrides is characterized by a DeltaG(double dagger) 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 H-2 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)