(mu u-Phenoxo)(2)(CoMII)-M-II complexes, [CoM(L)(AcO)]ClO4 (M = Mn (1), Fe (2), Co (3)) and [CoM(L)(NCS)]ClO4 (M = Mn (4), Fe (5), Co (6)), have been obtained where (L)(2-) is a heterodinucleating macrocycle derived by the 2:1:1 condensation of 2,6-diformyl-4-methylphenol, ethylenediamine, and diethylenetriamine and has two dissimilar N2O2 and N3O2 metal-binding sites sharing the phenolic oxygens. The complex 1 crystallizes in the monoclinic space group P2(1)/n, a = 13.346(2) Angstrom, b = 10.093(2) Angstrom, c = 22.049(2) Angstrom, beta = 104.58(1)degrees, V = 2874.3(7) Angstrom(3), and Z = 4. The refinement converges with R = 0.044 and R-W = 0.048 for 2948 reflections with \F-o\ > 3 sigma(\F-o\). The Co(II) resides at the ''salen''-like N2O2 Site and the Mn(II) at the N3O2 site. The exogenous acetate group bridges the two metal ions in the eta(1):eta(1) mode together with the two phenolic oxygens, providing a square-pyramidal geometry about the Co(II) and a distorted six-coordinate geometry about the Mn(II). The Co-Mn intermetallic separation is 3.132(1) Angstrom. The complexes 2 and 3 crystallize in the same triclinic space group . 2: a = 10.632(3) Angstrom, b = 15.326(2) Angstrom, c = 9.499(2) Angstrom, alpha = 106.64(1)degrees, beta = 106.27(2)degrees, gamma = 98.60(1)degrees, V = 1378.4(5) Angstrom(3), and Z = 2. 3: a = 10.6047(9) Angstrom, b = 15.268(2) Angstrom, c = 9.571(1) Angstrom, alpha = 107.262(10)degrees, beta = 105.894(8)degrees, gamma = 98.417(8)degrees, V = 1387.9(3) Angstrom(3), and Z = 2. They have a dinuclear core similar to that of 1. The complexes 4, 5, and 6 crystallize in the same monoclinic space group P2(1)/n. 4: a = 14.486(2) Angstrom, b = 12.460(2) Angstrom, c = 15.728(1) Angstrom, beta = 92.97(1)degrees, V = 2835.1(6) Angstrom(3), and Z = 4. 5: a = 14.273(1) Angstrom, b = 12.438(2) Angstrom, c = 15.814(1) Angstrom, beta = 93.279(7)degrees, V = 2802.8(6) Angstrom(3), and Z = 4. 6: a = 14.257(3) Angstrom, b = 12.391(2) Angstrom, c = 15.801(2) Angstrom, beta = 93.60(1)degrees, V = 2785.9(9) Angstrom(3), and Z = 4. The refinement for 4 converges with R = 0.065 and R-W = 0.064 for 2174 reflections with \F-o\ > 3 sigma(\F-o\). The Co(II) resides at the N2O2 Site and the Mn(II) at the N3O2 site. The Co-Mn separation bridged by the two phenolic oxygens is 3.175(2) Angstrom. The thiocyanate group coordinates to the Mn(II) ion through its nitrogen atom and to the Co(II) ion of the neighboring complex through its sulfur atom, forming a 1-D infinite chain extended by the Mn-NCS-Co linkage, The geometry about the Co(II) is square-pyramidal with the thiocyanate sulfur at the apex, and that about the Mn(II) is of a distorted six-coordination. The complexes 5 and 6 are isomorphous with 4 in the Co-Fe and Co-Co separation of 3.172(1) and 3.101(2) Angstrom, respectively. The magnetic studies reveal that the Co(II) at the N2O2 Site is of high spin in the acetate complexes 1-3, whereas it is of low spin in the thiocyanate complex:es 4-6. The MO ion at the N3O2 Site assumes high-spin state in all of the complexes. The physicochemical properties of the complexes are examined and discussed on the basis of the molecular structures and the spin states of the Co(IT) at the N2O2 site.