Synthesis, crystal structures and magnetic behavior of two 3D coordination polymers using N-(4/3-carboxyphenyl)iminodiacetic acids as bridging ligands

摘要

Research on structure and magnetic properties of polynuclear metal complexes to understand the structural and chemical factors governing the electronic exchange coupling mediated by multi-atom bridging ligands is of growing interest. Hydrothermal treatment of Ni(NO_3) _2·6H_2O with N-(4-carboxyphenyl)iminodiacetic acid [N-4(H_3CPIDA)] at 150 °C yielded a 3D coordination polymer of general formula [Ni_3{N-4(CPIDA)}_2(H_2O) _3]·6H_2O (1). An analogous network of general formula [Co_3{N-3(CPIDA)}_2(H_2O) 3]·3H_2O (2) was synthesized using N-(3-carboxyphenyl)iminodiacetic acid [N-3(H_3CPIDA)] in combination with Co(NO_3)_2·6H_2O under identical reaction condition. Both the complexes contain trinuclear secondary building unit, and crystallized in monoclinic system with space groups C2/c (1) and P2_1/c (2), respectively. Variable temperature magnetic characterization of these complexes in the temperature range of 2-300 K indicated the presence of overall ferromagnetic and antiferromagnetic behavior for 1 and 2, respectively. Density functional theory calculations (B3LYP functional) were performed for further insight on the trinuclear units to provide a qualitative theoretical interpretation on the overall magnetic behavior of the complexes 1 and 2.