Employing [Fe(C2O4)(3)](3)-(C2O42-= oxalate) metallotectons as building units, a series of 3D iron-organic compounds with formulae [K(H-L-1)(2)(Fe(C2O4((3))center dot 2H(2)O]1, [(H-Phen)(Fe (C204)2)(Phen).3H(2)O] f(H-2-L-2)(2){Fe-2(C2O)(3)Cl-)] 3, [K(H-2-L-7)(Fe(C2O)(3))-2H(2)O 4, [K(1-12-L-4)(Fe(C204)3)-H20] 5, [(H-L5){Fe(C2O4(L5))] 6, f(H-2-L-6](Fe-2(C2O)(4)(OH2)center dot 2H(2)O] 7, [(H-L7)(4){Fe(C2O4)(3))-2H(2)O 8 (with Li* = 2-methyrbenzimidazole, Phen = 1,10-phenanthroline, L-2 1,4-bis(imidazol-1-ylmethyOloenzene, L-3 = 1,4-bis((2-methylimidazoi-1yilmethyl)benzene, L-4 = 1,1'-butane-1,4-diyIbis(1H-imidazole), H-L-5 = 1H-benzotriazole, L-6 = 1,2-et hylenediamine, L-7 = melamine) have been synthesized and characterized by single-crystal X-ray diffraction. Compounds 1 and 5 possess different 2D [KFe(C204)3](2-)layers. Compound 2 features a 2D hydrogen bonded network completed by trimer water clusters and [Fe(C204)2(Phen)r anions via hydrogen bonds. Compounds 3-6 feature a series of 2D layers, which are further extended into a 3D supramolecular structure through C-H.-0 hydrogen bonds. Distinct [Fe-2(C2O4)Cl4]-units and [Fe2(C204)4(OH)214-units are shown in compounds 3 and 7, respectively. Trinary hydrogen bonds and double hydrogen bonds are simultaneously displayed in 8 as well as N-H CI and O-H ... Cl hydrogen bonds. Furthermore in order to examine the thermal stability of all compounds, TGA was carried out.