pH-Dependent Cu(II) Coordination Polymers with Tetrazole-1-acetic Acid: Synthesis, Crystal Structures, EPR and Magnetic Properties

Four novel copper tetrazole-1-acetic acid (Htza) coordination polymers, namely, {[Cu(tza) 2 (Htza) 2 ]·2H 2 O} n ( 1 ), [Cu(tza) 2 ] n ( 2 ), {[Cu 4 (tza) 4 (CH 3 COO) 2 (μ 3 -OH) 2 (H 2 O) 2 ]·2H 2 O} n ( 3 ), and {[Cu 4 (tza) 6 (μ 3 -OH) 2 ]·4H 2 O} n ( 4 ), were synthesized as pH-dependent products and characterized by elemental analysis, Fourier transform infrared (FT-IR) spectra, electron paramagnetic resonance (EPR), magnetic properties, and single-crystal X-ray diffraction studies. In 1, two neighboring copper ions are bridged by two carboxylato groups from two tza ligands in a syn − anti bridging mode, forming a one-dimensional Cu chain. 2 is a two-dimensional (2D) wavelike layer based on {Cu(tza)} 4 rings from head-to-tail arranged tza ions. 3 and 4 are 2D coordination polymers containing tetranuclear Cu 4 (μ 3 -OH) 2 units.