Self-assembly of two mixed-ligands metal-organic coordination polymers, [MII2(DPA)2(C4O4)(C2O4)] (M = Cu, Zn)

Two coordination polymers with the formula of [M2(DPA)2(C4O4)(C2O4)]∞ (M=Cu 1, Zn 2; DPA=dipyridylamine) were synthesized under hydrothermal conditions. Both complexes are crystallized in triclinic system, space group P1̄ with the cell parameters: a=8.3078(3) Å, b=9.1192(3) Å, c=9.2316(3) Å, α=115.164(1)°, β=94.283(1)°, γ=103.559(1)°, V=603.17(4) Å3, Z=2 for complex 1 and a=8.5348(2) Å, b=9.0451(2) Å, c=9.0862(3) Å, α=114.305(1)°, β=100.493(1)°, γ=97.318(1)°, V=612.34(2) Å3, Z=2 for complex 2, respectively. X-ray single-crystal structural determinations reveal that these two complexes are both composed of one-dimensional zigzag chains built up via the [M(DPA)]2+ fragments and alternately bridged bidentate μ1,3-C4O42−, tetradentate C2O42− ligands. The coordination environments of the M(II) centers adopt a slightly distorted trigonal bipyramid bonded with two N atoms of DPA, one O atom of squatate and two O atoms of oxalates. The intrachains N–H⋯O and C–H⋯O hydrogen bonds play an important role on the additional stabilization in constructing the open frameworks.