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]·2H2O} n (1), [Cu(tza)2] n (2), {[Cu4(tza)4(CH3COO)2(μ3-OH)2(H2O)2]·2H2O} n (3), and {[Cu4(tza)6(μ3-OH)2]·4H2O} 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 Cu4(μ3-OH)2 units.