Water-soluble complexes are desirable for the aqueous detoxification of cyanide. Molybdenum complexes with alpha-amino acid and disulfide ligands with the formula K[(L)Mo2O2(mu-S)(2)(S-2)] (L = leu (1), met (2), thr (3), and ser (4)) were synthesized in a reaction of [(DMF)(3)MoO(mu-S)(2)(S-2)] with deprotonated alpha-amino acids; leu, met, thr, and ser are the carboxylate anions of L-leucine, L-methionine, L-threonine, and L-serine, respectively. Potassium salts of alpha-amino acids (leu (1a), met (2a), thr (3a), and ser (4a)) were prepared as precursors for complexes 1-4, respectively, by employing a nonaqueous synthesis route. The ligand exchange reaction of Mo2O2(mu-S)(2)(DMF)(6)](I)(2) with deprotonated alpha-amino acids afforded bis-alpha-amino acid complexes, [(L)(2)Mo2O2(mu-S)(2)] (6-8). A tris-alpha-amino acid complex, [(leu)Mo2O2(mu-S)(2) (mu-leu + H)] (5; leu + H is the carboxylate anion of L-Ieucine with the amine protonated), formed in the reaction with leucine. 5 crystallized from methanol with a third weakly bonded leucine as a bridging bidentate carboxylate. An adduct of 8 with SCN- coordinated, 9, crystallized and was structurally characterized. Complexes 1-4 are air stable and highly water-soluble chiral molecules. Cytotoxicity studies in the A549 cell line gave IC50 values that range from 80 to 400 mu M. Cyclic voltammetry traces of 1-8 show solvent-dependent irreversible electrochemical behavior. Complexes 1-4 demonstrated the ability to catalyze the reaction of thiosulfate and cyanide in vitro to exhaustively transform cyanide to thiocyanate in less than 1 h.