Zn(NO 3) 2, Cd(NO 3) 2 and Cd(ClO 4) 2 form trans-octahedral M(H 2biim) 2L 2 n+ species, where H 2biim is chelating bidentate and the apical ligands are H 2O, CH 3OH or counter-anions, whereas tetrahedral Zn(H 2biim)Cl 2 is obtained from ZnCl 2. The tris-chelate Cd(H 2biim) 3 2(SiF 6)(BF 4) 2 · 6EtOH is isolated from Cd(BF 4) 2 reacted in a glass vessel. Hydrogen bonding plays a determining role in crystal packing. The reactions of zinc and cadmium salts with 2,2′-biimidazole (H 2biim) yielded a series of compounds in which the ligand is coordinated in the chelating bidentate mode. ZnCl 2 and Ag(H 2biim)(NO 3) in methanol in a 2:1 proportion produced Zn(H 2biim)Cl 2, in which the metal has a distorted tetrahedral coordination. A 1:2 ratio led to Zn(H 2biim) 2(CH 3OH) 2(NO 3) 2, containing an octahedrally coordinated Zn(II) center with the O-bonded methanol ligands occupying trans positions. The corresponding Cd(H 2biim) 2(CH 3OH) 2(NO 3) 2 compound was obtained from CdCl 2. By starting with Cd(NO 3) 2 and Cd(ClO 4) 2 in aqueous media, the related octahedral bis-chelate compounds Cd(H 2biim) 2(NO 3)(H 2O)(NO 3) and Cd(H 2biim) 2(ClO 4) 2, respectively, were isolated, the apical positions being filled by perchlorate oxygens in the latter case. With Cd(BF 4) 2, the glass container participated in the reaction and a tris-chelate complex Cd(H 2biim) 3 2(SiF 6)(BF 4) 2 · 6EtOH was isolated. The Cd(H 2biim) 3 2+ and SiF 6 2 - ions define an extended hydrogen-bonded network, in which BF 4 - ions surrounded by disordered ethanol molecules occupy large cavities. The two free N–H groups provide H 2biim with a unique ability to form hydrogen bonds and their interactions with counter anions or other acceptors play a determining role in controlling molecular packing. The IR spectra of all compounds are discussed.