Two novel coinage metal(I)-triphenylphosphine complexes with a heterocyclic ligand, [Ag(tetz)(PPh 3) 2] n ( 1) and [Au(tetz)(PPh 3)] ( 2) (Htetz=tetrazole) were synthesized from a reaction in dichloromethane of the precursor complex [Ag(tetz)] n with PPh 3 and from a reaction in acetone of [AuCl(PPh 3)] with Htetz in the presence of aqueous NaOH, respectively, and isolated as colorless needle crystals for both 1 and 2. The crystal structures of 1 and 2 were determined by single-crystal X-ray diffraction. These d 10 complexes were also fully characterized by elemental analyses, TG/DTA and FT-IR in the solid-state, solution NMR ( 31P, 1H and 13C, as well as 109Ag for 1) spectroscopies and solution molecular weight measurements. Complex 1, is composed of a helical polymer, a 2 1 helix with a pitch 9.471 Å, formed by a bridged tetrazolate of an AgNP 2 core in the solid-state, but it was present as a monomer in solution. In contrast to 1, complex 2 consisted of a monomeric two-coordinate AuNP core without gold(I)–gold(I) interaction both in the solid-state and in solution. The molecular structures of 1 and 2 were compared with those of the corresponding triazole complexes, i.e. silver(I) complexes [Ag(1,2,3-triz)(PPh 3) 2] n ( 3) and [Ag(1,2,4-triz)(PPh 3) 2] n ( 4) both as helical polymers, a monomeric gold(I) complex [Au(1,2,3-triz)(PPh 3)] ( 5) and a dimeric gold(I) complex [Au(1,2,4-triz)(PPh 3)] 2 ( 6) through an intramolecular gold(I)–gold(I) bond; the structures of complexes 3– 6 being recently determined by X-ray crystallography. The antimicrobial activities of 1, its precursor [Ag(tetz)] n and 2 were compared and key factors affecting them discussed.