Copper benzenedicarboxylate coordination polymers incorporating a long-spanning neutral co-ligand: Effect of anion inclusion and carboxylate pendant-arm length on topology and magnetism

Three divalent copper coordination polymers containing aromatic dicarboxylate ligands and the long-spanning tethering imine bis(4-pyridylmethyl)piperazine (bpmp) have been prepared and structurally characterized. The length of the dicarboxylate pendant arms, carboxylate binding mode, and the inclusion of anionic components play a synergistic role in structure direction in this system. {[Cu(ip)(bpmp)(H2O)]·5H2O}n (ip = isophthalate, 1) displays neutral (4,4) rectangular coordination polymer grids that stack in an ABCD repeat pattern. Use of the longer pendant arm dicarboxylate 1,3-phenylenediacetate (phda) resulted in {[Cu2(phda)2(bpmp)]·H2O}n (2), a 3-D network coordination polymer with primitive cubic topology that features strongly antiferromagnetically coupled (J = −331(1) cm−1) {Cu2(CO2)4} paddlewheel units. In the presence of excess nitrate ions, {[Cu(phda)(Hbpmp)](NO3)·3H2O}n (3) was isolated instead of 2; 3 manifests cationic 2-D coordination polymer layers built from weakly antiferromagnetically coupled (J = −2.43(1) cm−1) {Cu2O2} dimers linked through phda and protonated bpmp ligands. The striking difference in magnetic properties is ascribed to the equatorial–equatorial versus axial–equatorial bridging of copper coordination spheres in 2 and 3, respectively.

{[Cu(ip)(4-bpmp)(H2O)]·5H2O}n (ip = isophthalate, 4-bpmp = bis(4-pyridylmethyl)piperazine, 1) displays coordination polymer grids that stack in an ABCD repeat pattern. {[Cu2(phda)2(4-bpmp)]·H2O}n (phda = 1,3-phenylenediacetate, 2) has a primitive cubic topology and features strongly antiferromagnetically coupled {Cu2(CO2)4} paddlewheel units. In the presence of excess nitrate {[Cu(phda)(H4-bpmp)](NO3)·3H2O}n (3) was isolated. 3 manifests cationic 2-D coordination polymer layers built from weakly antiferromagnetically coupled {Cu2O2} dimers linked through phda and protonated bpmp ligands.Figure optionsDownload as PowerPoint slide