Four complexes, [Fe-II(bimH(2))(2)(CH3OH)(2)](OAc)(2) (1), [Fe-II(bimH(2))(3)]CO3 (2), [Fe-II(bimH)(2)](n) (3) and {Fe-II(bim)}(n) (4), wherein bimH(2) = 2,2’-biimidazole, bimH(-) = biimidazolate monoanion, and bim2(-) = biimidazolate dianion, have been synthesized and studied. 1 crystallizes in the monoclinic system, space group P2(1)/n, Z = 2, a 9.021(1) Angstrom, b = 7.413(1) Angstrom, c = 17.700(2) Angstrom, beta = 97.23(1)degrees; 2 crystallizes in the tetragonal system, space group I4(1), Z = 4, a = b = 12.219(1) Angstrom, 14.334(2) Angstrom; 3 crystallizes in the tetragonal system, space group P4(3), Z = 4, a = b = 8.5144(7) Angstrom, c = 18.273(3) Angstrom. The structures were solved by direct methods and refined to conventional agreement indices R = 0.024 (1), 0.022 (2), and 0.032 (3) and R(W) = 0.024 (1), 0.023 (2), and 0.039 (3) with 1725 (1), 2292 (2), and 2592 (3) unique reflections for which I > 3 sigma(I). The molecular structure of 1 consists of [Fe-II(bimH(2))(2)(CH3OH)(2)](2+) complex cations and acetate anions associated into infinite chains along a through hydrogen bonds involving the amine nitrogen atoms of all bimH(2) ligands, all coordinated methanol molecules and en atoms constituting the distorted coordination octahedron around each Fe(II) riginate from two chelating bimH(2) ligands and two methanol molecules. The structure of 2 consists of [Fe-II(bimH(2))(3)](2+) complex cations hydrogen bonded to carbonate dianions. The coordination geometry of the iron(II) center can be described as a distorted octahedron includind six nitrogen atoms originating from three chelating bimH(2) ligands.The ferrous center of each [Fe-II(bimH)(2)] neutral unit of 3 is chelated to two biimidazolate monoanions cis to each other. Two deprotonated amine nitrogen donors arising from biimidazolate ligands of adjacent complex molecules supplement the iron(II) coordination octahedron. All iron atoms situated at the same z value are bridged through the imidazolate rings affording a sheet spanning along a,b. These sheets are associated together into a 3D network in which each [Fe-II(bimH)(2)] molecule is linked to four nearest neighbors through N-C-N bridges. The synthesis, molecular crystal structure, IR, Mossbauer, and magnetic susceptibility studies of 1-4 evidence the variety of structural types and properties obtained for iron(II) complexes of 2,2’-biimidazole and derived biimidazolate anions. Complex 1 is the first example of structurally characterized mononuclear ferrous compound including two bidentate bimH(2) and two monodentate oxygenated ligands affording a N4O2 coordination sphere to high-spin iron(II). Synthesis of 2 from Fe-II(bimH(2))(2)(HCOO)(2) and CO3HNa shows that formate anions ate readily displaced from the iron(II) coordination sphere as shown for the non-heme iron(II) of photosystem 2. 3 affords the first example of bridging biimidazolate monoanion.4 is the first inorganic polymeric material including the bim(2-) dianion as tetradentate bridging ligand. The Mossbauer and magnetic properties of 4 indicate the presence of a weak ferromagnetic ground state resulting from the 3D ordering of this homometallic 3 and 4 are the first examples of iron compounds including the biimidazolate monoanion (bimH(-)) and the biimidazolate dianion (bim(2-)), respectively.