Transition metal complexes of ditertiary aminomethylphosphine ligand, (Ph2PCH2)NCH3 [N, N-bis (diphenylphospinomethyl)aminomethane], dppam, with metal ions which are Ag(I), Au (I), Cu (I), and Co (II) have been synthesized under nitrogen atmosphere by the Schlenk method. [Ag(dppam)(2)]NO3 (1), [Au (dppam)(2)]Cl (2), and [Cu (dppam)(2)]Cl (3) complexes have been isolated as colorless solids, whereas [COCl2(dppam)] (4) complex as a blue solid. All complexes have been characterized by atomic absorption, FT-IR, NMR (H-1, C-13, (31)p) spectroscopic, thermogravimetric/differantial thermal analysis (TG/DTA), and elemental analysis techniques. Antimicrobial activity of 1, 2, 3, and 4 were studied in vitro on 13 bacteria and 4 yeasts. The cobalt (II) phosphine complex has shown the best antimicrobial activity in comparison with the other metal complexes. (c) 2005 Wiley Periodicals, Inc.