Two New Coordination Polymers with Co(II) and Mn(II): Selective Gas Adsorption and Magnetic Studies

Abstract

A novel bifurcated ligand 3,5-di(1H-benzo[d]imidazol-1-yl)benzonitrile (DBIBN) was synthesized, which reacts with Co(II) and Mn(II) salts to form new coordination polymers {[Co2(DBIBA)3]·Cl·9H2O}n (1) and {[Mn3(DBIBA)6]}n (2), (DBIBA = 3,5-di(1H-benzo[d]imidazol-1-yl)benzoate), in which DBIBN get hydrolyzed into DBIBA under solvothermal conditions. Both the complexes were characterized by single-crystal x-ray crystallog. (XRD), IR spectroscopy, elemental anal., TG, and X-ray powder diffraction (PXRD). Complex 1 is a 3-dimensional coordination polymer composed of binuclear Co(II) units, having (4,6) connected net. However, complex 2 is a layered structure with trinuclear Mn(II) units, which has 4-connected 44sql topol. TGA and PXRD measurements show that the framework 1 is stable after desolvation. Desolvated framework 1 showed selective adsorption of CO2 over N2, H2, and Ar. Variable temp. magnetic susceptibility measurements show that complex 2 exhibits weak antiferromagnetic behavior.