An unprecedented coordination mode of isonicotinate ligand in novel copper(II) polymeric complex: synthesis, spectral, thermal and magnetic properties and their comparison with known molecular analog

Two copper(II) isonicotinate complexes, [Cu(INA)2(H2O)4] (1) and {[Cu(INA-N-H)2(μ2-H2O)2]·2H2O·2NO3}n (2) were prepared using a one-pot synthesis and characterized by single-crystal X-ray diffraction, spectral and thermal analysis and magnetic susceptibility. Complex 1 provides Cu–N(pyridyl) coordination mode with ionic carboxylate functionality. A novel complex 2 exhibits a chain-like crystal structure in which the [Cu(INA-N-H)]2+ ions are bridged by μ2-H2O molecules. The structural, spectral and thermal correlations indicate significant influence of ligand coordination mode and non-covalent interactions to mentioned properties. Magnetic susceptibility data were fitted by Curie–Weiss law with Tc = 0.68 K for complex 1 and Tc = 9.01 K for complex 2. Magnetic studies show a very weak interaction between copper(II) centers within the network structure in complex 1 and stronger ferromagnetic coupling between Cu ions caused by the presence of intra-chain Cu–O–Cu interaction in complex 2.