Synthesis, structure and property of cobalt(II) complexes with 3,5-di(1H-imidazol-1-yl)benzoic acid

Two novel cobalt(II) complexes (Co(L)(NO3)] (1) and [Co(L)(H2O)(2)]ClO4 (2) were synthesized by reactions of 3,5-di(1H-imidazol-1-yl)benzoic acid (HL) with corresponding cobalt(II) salts, and their structures were determined by single crystal X-ray diffraction analysis. In the title complexes, the carboxylate group of L- ligand adopts a mu(2)-eta(1):eta(1)-bridging mode to connect two cobalt(II) atoms, and each L- ligand acts as a 4-connector, and the cobalt(II) has distorted octahedral coordination geometry. In 1, one oxygen atom of the nitrate anion links two cobalt(II) atoms to complete a 3D structure which is a binodal (4,6)-connected net with Schlafli symbol of (3-4(2).5(2).6)(3(2).4(2).5(2).6(4).7(4).8). While in 2, the 3D structure has topology related to SrAl2, CeCu2 and KHg2 With Schlafli symbol of (4(2).6(3).8) and there are ID channels filled with perchlorate anions. The results revealed that the nature of the counteranions, such as their shape, size and coordination ability, has a remarkable influence on the structure of the complexes. The results of the magnetic measurements showed that there are antiferromagnetic interactions between the neighboring Co(II). Furthermore, complex 2 exhibited a modest second-harmonic-generation (SHG) efficiency and anion-exchange property.