A series of heterodinuclear complexes Cu(II)M, where M = Cr(III) (1), Mn(III) (2), Mn(II) (3), Fe(III) (4), Co(II) (5), Co(III) (6), Ni(II) (7), Cu(II) (8), and Zn(II) (9), containing the oximato dianion (Dopn2-) as bridging ligand and 1,4,7-trimethyl-1,4,7-triazacyclononane (L) as one of the two capping ligands have been synthesized by using the [Cu(DopnH)]+ cation (H2Dopn = 3,9-dimethyl-4,8-diazaundeca-3,8-diene-2,10-dione dioxime) as a ligand for the different ML(n+) centers. The compounds have been characterized on the basis of IR, electronic, and EPR spectroscopy and variable-temperature (2-295 K) magnetic susceptibility measurements. The dinuclear complexes are quasi-isostructural with the copper(II) ion in a distorted square pyramidal environment, CuN4O, and the M ion, except for that in 8, is six-coordinate with the MN3O3 or MN3O2Cl coordination sphere. For M = Cu (8), the coordination geometry of M with the CuN3O2 chromophore is also square pyramidal. The crystal and molecular structures of the compounds [(Dopn)Cu(II)(OH2)Cr(III)(OCH3)L](ClO4)2.H2O (1) and [(Dopn)Cu(II)(mu-CH3COO)-Mn(III)L](ClO4)2.2H2O (2) have been established by X-ray diffraction. 1 crystallizes in the monoclinic system space group P2(1)/n, with cell constants a = 13.096(3) angstrom, b = 17.933(4) angstrom, c = 15.994(3) angstrom, beta = 113.49(3)-degrees, V = 3444.9(13) angstrom3, and Z = 4. The structure consists of oximato-bridged Cu(II)Cr(III) dications and noncoordinated perchlorate anions, with a Cu...Cr distance of 3.86 angstrom. The crystal data for 2 are as follows : orthorhombic, space group P2(1)2(1)2(1), a = 12.275(4) angstrom, b = 14.171(9) angstrom, c = 19.780(3) angstrom, V = 3441(2) angstrom3, Z = 4. : orthorhombic, space group P2(1)2(1)2(1), a = 12.275(4) angstrom, b = 14.171(9) angstrom, c = 19.780(3) angstrom, V = 3441(2) angstrom3, Z = 4.