ISABELLE SEGALAS and ANDRE L. BEAUCHAMP. Can. J. Chem. 70, 943 (1992). The reaction of 4-nitroimidazole (NOJmH) with AgN0, and AgBF, in neutral or weakly acidic aqueous media yielded the insoluble [Ag(N021m)] compound, whose infrared and "C NMR spectra are consistent with a polymeric chain of deprotonated ligands bridging silver atoms via the endocyclic nitrogen atoms. In strongly acidic solution, [Ag(N021mH),]X salts (X = NO,, BF,) were obtained and their crystal structures were determined. [Ag(N021mH)2]N0,: monoclinic, P2/n, a = 14.214(1), b = 12.571(2), c = 14.222(1) A, P = 111.38(7)", Z = 8, R = 0.021, 3443 observed reflections; [Ag(N021mH)2]BF,: monoclinic, P 2 , / c , n = 9.543(4), b = 6.478(2), c = 20.869(9) A, P = 90.84(3)", Z = 4, R = 0.027, 1646 observed reflections. In both compounds, the two-coordinated metal forms roughly collinear bonds to two neutral ligands via the endocyclic nitrogen atom adjacent to the nitro group. One oxygen of each nitro group makes a secondary Ag-0 bond near the equatorial plane. 'The anions are hydrogen bonded to the ligand N-H groups and do not directly interact with the metal. Solution 'H and "C NMR spectra show that the cationic complexes dissociate in DMSO. The infrared and CP-MAS "C NMR spectra are discussed in connection with the coordination patterns observed.Key words: silver, imidazole, crystal structure, infrared spectroscopy, nuclear magnetic resonance.