Synthesis, characterization, and solid state electrical conductivity of coordination polymers with copper and zinc

Abstract

Heterobimetallic complexes [Cu x Zn1− x (dadb) · yH2O] n {where dadb = 2,5-diamino-3,6-dichloro-1,4-benzoquinone (1); x = 1 (2), 0.5 (4), 0.25 (5), 0.125 (6), 0.0625 (7), and 0 (3); y = 2; n = degree of polymerization} were synthesized and characterized. All metal complexes are stable at room temperature but weakly absorb moisture on exposure to air. Monometallic 2 exhibits subnormal magnetic moment whereas 3 exhibits diamagnetism. Heterobimetallic complexes exhibit normal magnetic moments. Heterobimetallic complexes are characterized from powder X-ray diffraction, thermal analysis, and electron spin resonance (ESR) spectral studies. Delocalization of unpaired electron from metal to ligand has been inferred from ESR and natural bond orbital (NBO) analysis. Greater delocalization of unpaired electron of Cu(II) on ligand of 4 as compared to that of 2 is reflected from NBO analysis. Heterobimetallic complexes show higher conductivity than monometallic complexes; all the complexes exhibit semiconductor behavior.