Preparations of the compounds [{Ni(1,3-pn)2}2C2O4](ClO4)2,H2O, [{Ni(dpt)H2O}2C2O4](ClO4)2, [{Cu(dien)}2C2O4](ClO4)2(and hydrate), [{Cu(dpt)}2C2O4](ClO4)2, [{Zn(en)2}2C2O4](ClO4)2, [{Zn(dpt)}2C2O4](ClO4)2, and [{Zn(trien)}2C2O4](ClO4)2, considered to have dimeric structures with bridging bichelate oxalate ions, are described. The pairs of compounds [{M(en)2}2C2O4](ClO4)2 and [{M(trien)}2C2O4](ClO4)2[M = Ni(II) or Zn(II)] are isostructural, whereas the pair [{M(dpt)}2C2O4](ClO4)2[M = Cu(II) or Zn(II)] are not isostructural. The racemic isomer of the cyclic tetramine 5,7,7,12,14,14-hexamethyl-1,4,8,11-tetra-azacyclotetradecane forms an analogous compound, [{Ni(tet b)}2C2O4](ClO4)2, whereas the meso-isomer forms only a simple oxalate, Ni(tet a)C2O4, and its trihydrate, considered to have polymeric structures with bridging, bi-unidentate oxalate ions. The compounds [Zn(1,3-pn)2](ClO4)2 and [Zn3(trien)4](ClO4)6 were also prepared. Infrared spectra and magnetic susceptibilities (µeff∼ 3 B.M. for the nickel compounds and ∼1·8 B.M. for the copper compounds) are reported (en = diaminoethane; 1,3-pn = 1,3-diaminopropane; dien = diethylenetriamine; dpt = dipropylenetriamine; trien = triethylenetetramine).