A series of zinc-containing heterodimetallic complexes were prepared by using the dinucleating ligand XDK [H(2)XDK = m-xylylenediamine bis(Kemp’s triacid imide)]. Mononuclear [Zn(XDK)(H2O)] (1) reacts with 1 equiv of M(acac)(2) . 2H(2)O (acac = 2,4-pentanedionate) to afford the heterodimetallic compounds [Zn(II)M(II)(XDK)(acac)(2)(CH3OH)(2)]. H2O (2 . H2O, M = Co, 65% isolated yield; 3 . H2O, M = Mn, 54%; 4 . H2O, M Fe, 30%; 5 . H2O, M = Ni, 32%). As determined by X-ray crystallography, 2-5 each contain a Zn(II)M(II) dinuclear core bridged by XDK and acac ligands. The zinc and M atoms have trigonal bipyramidal and octahedral geometries, respectively. The Zn M separations depend on the metal ion in the octahedral site (2, M = Co, 3.440(2) Angstrom; 3, M = Mn, 3.517(1) Angstrom; 4, M = Fe, 3.492(1) Angstrom; 5, M = Ni, 3.397(1) Angstrom), a variation which is correlated with the ionic radius of the high-spin octahedral metal ion. The reaction of 2 with diphenyl hydrogen phosphate afforded the bis(phosphate) complex [ZnCo(XDK){mu-eta(2)-(PhO)(2)PO2}{eta(1)-(PhO)(2)PO2}(CH3OH)(2)(H2O)] (7, 49% yield).The ZnCo center is bridged by the XDK through its two carboxylate groups and by a diphenyl phosphate ligand. The other diphenyl phosphate is terminally coordinated to the zinc atom in a monodentate fashion. The Zn...Co interatomic istance is 3.846(1) Angstrom. An analogous bis(phosphate) homodinuclear complex, [Zn-2(XDK){mu-eta(2)-(PhO)(2)PO2}{eta(1)-(PhO)(2)PO2}(CH3OH)(2)(H2O)] (8), was prepared by reacting [Zn-2(XDK)(acac)(2)(CH3OH)(2)] (6) with diphenyl hydrogen phosphate in 64% yield. Compound 8, which is isomorphous with 7, has an asymmetrical dizinc core bridged by XDK and a phosphate ligand (Zn...Zn = 3.869(2) Angstrom). The monodentate diphenyl phosphate ligand dissociates from the dimetallic center of 8 in solution, as revealed by molar conductivity and H-1 and P-31{H-1} NMR spectroscopic studies. The resulting free phosphate ligand exchanges with the bridging one in methanol-d(4). The present results provide a useful synthetic route to carboxylate-bridged heterodimetallic compounds, which are potential models for the active centers in nonredox metalloproteins. Crystal data are as follows. 2: monoclinic, P2(1)/c, a = 17.725(7) Angstrom, b = 12.354(4) Angstrom, 21.815(6) Angstrom, beta = 90.45(3)degrees, V = 4777(2) Angstrom(3), Z = 4; R = 0.049 and R(w) = 0.051 for 3884 reflections with I > 3 sigma(I). 3: monoclinic, P2(1)/c, a 17.292(2) Angstrom, b = 12.450(1) Angstrom, c 21.717(2) Angstrom, beta = 91.464(7)degrees,V = 4673.9(7) Angstrom(3), Z = 4; R = 0.046 and R(w) = 0.051 for 3876 reflections. 4: monoclinic, P2(1)/c, a 17.630(1) Angstrom, b = 12.374(2) Angstrom, c = 21.771(2) Angstrom, beta = 90.306(8)degrees, V = 4749.4(7) Angstrom(3), Z = 4; R = 0.041 and R(w) 0.049 for 3248 reflections. 5: monoclinic, P2(1)/c, a 17.817(2) Angstrom, b = 12.241(3) Angstrom, c = 21.786(2) Angstrom, beta = 91.043(9)degrees, V = 4751(1) Angstrom(3), Z = 4; R = 0.050 and R(w) = 0.058 for 4497 reflections. 7 . CH3OH: monoclinic, P2(1)/n, a = 18.812(2) Angstrom(3), b = 16.156(2) Angstrom, c = 836(9)degrees, V = 6095(1) Angstrom(3), Z = 4; R = 0.055 and R(w) = 0.064 for 5843 reflections. 8 . CH3OH: monoclinic, P2(1)/n, a 18.845(6) Angstrom, b = 16.105(3) Angstrom, c = 21.776(3) Angstrom, beta = 112.78(2)degrees, V = 6091(2) Angstrom(3), Z = 4; R = 0.055 and R(w) = 0.061 for 5189 reflections.