Our group is interested in the design, synthesis, and reactivity of water-soluble organometallic complexes utilizing the air-stable and water-soluble phosphine 1,3,5-triaza-7-phosphaadamantane (PTA) and derivatives. Herein, we report on the synthesis, isolation, and characterization of a series of water-soluble complexes with the general formula Cp'Ru(PTA)(PR₃)X (where PR₃ = PTA or PPh₃; X = Cl, H; and Cp' = various Cp or Tp ligand sets) and their reactivity with acids and bases. The Cp'RuPTA(PR₃)H complexes may be used to catalyze the hydrogenation of C=C bonds in water. Mechanistic details of this process including pH, salt, and H₂ pressure effects will be discussed. Based on these studies it is postulated that hydrogenation occurs via an ionic mechanism. In particular, we will describe computational and experimental work carried out in our laboratories related to the protonation of CpRu(PTA)₂H, the consequences of protonation in catalytic reactions, and H/D exchange reactions the Ru-H bond undergoes with D₂O.