Reaction of M(NO3)(2). chiH(2)O (M = Mn, Co, Ni, Cu, Zn) with 3-diphenylamino-4-hydroxycyclobut-3-ene- 1,2-dione (diphenylaminosquarate) produces the neutral polymeric species {M[mu-(C6H5)(2)NC4O3](2)[H2O](2)}(n) [M = Mn (1), Cu (2)]; {M[mu-(C6H5)(2)NC4O3][(C6H5)(2)NC4O3][H2O3)}(n) [M = Co (3), Zn (4)]; and in the case of Ni, the salt [Ni(H2O)(6)] [(C6H5)(2)NC4O3](2). 2H(2)O (5). Complexes 1 and 2 are isomorphous and crystallize in the monoclinic space group P2(1)/c with, for 1, a = 13.138(1) Angstrom, b = 10.900(2) Angstrom, c = 9.269(2) Angstrom, beta = 96.07(1)degrees, Z = 2. Complexes 3 and 4 are also isomorphous and crystallize in the space group P2(1)/c with, for 3, a = 13.211(1) Angstrom, b = 11.038(1) Angstrom, c = 18.748(1) Angstrom, beta = 97.75(1)degrees, and Z = 4. The nickel salt, 5, crystallizes in the triclinic space group P1 with a = 6.181(1) Angstrom, b = 9.417(1) Angstrom, c = 15.486(1) Angstrom, alpha = 101.37(1)degrees, beta = 95.51(1)degrees, gamma = 107.57(1)degrees, and Z = 1. In 1 and 2, the metal coordination is octahedral, comprising four mu -1,3-bridging diphenylaminosquarate ligands and two trans aqua ligands. In 3 and 4, the metal coordination is again octahedral, comprising two mu -1,3-bridging and one pendant diphenylaminosquarate ligands, the octahedron being completed by three aqua ligands in a meridional configuration. In 5, the hexaaquanickel(II) ion is linked by O-H . . .O hydrogen bonds to a pair of diphenylaminosquarate anions. These anion-cation units are linked via included water molecules to form hydrogen-bonded chains. The diphenylaminosquarate ligands in the polymeric complexes 1-4 display multiple-bond localization, a feature which is absent in 5. Complex 1 exhibits weak antiferromagnetic coupling, whereas 2 shows no significant magnetic interactions.