A series of ruthenium complexes was isolated and characterized in the course of reactions aimed at studying the reduction of hydrazine to ammonia in bimetallic systems. The diruthenium complex {[HPNPRu(N-2)](2)(mu-Cl)(2)}(BF4)(2) (2) (HPNP = HN(CH(2)CH(2)PiPr(2))(2)) reacted with 1 equiv of hydrazine to generate [(HPNPRu)(2)(mu(2)-H2NNH2)O-4-Cl)(2)](BF4)(2) (3) and with an excess of the reagent to form [HPNPRu(NH3)(kappa(2)-N2H4)](BF4)Cl (5). When phenylhydrazine was added to 2, the diazene species [(HPNPRu)(2)(mu(HNNPh)-H-2)(mu-Cl)(2)](BF4)(2) (4) was obtained. Treatment of 2 with H-2 or CO yielded {[HPNPRu(H-2)](2)(mu-Cl)(2)}(BF4)(2) (7) and [HPNPRuCl(CO)(2)]BF4 (8), respectively. Abstraction of chloride using AgOSO2CF3 or AgBPh4 afforded the species [(HPNPRu)(2)(mu(2)-OSO2CF3)(mu-Cl)(2)]OSO2CF3 (9) and [(HPNPRu)(2)(mu-Cl)(3)]BPh4 (10), respectively. Complex 3 reacted with HCl/H2O or HCl/Et2O to produce ammonia stoichiometrically; the complex catalytically disproportionates hydrazine to generate ammonia.