Synthesis, crystal structure, and magnetic behavior of two dicyanamido-bridged complexes of manganese(II): effect of weak interaction in carving regular geometry

Abstract

Two new dicyanamido-bridged polymeric complexes of manganese(II), [Mn(dca)₂(pic)₂]_n 1 and [Mn(dca)₂(biim)]_n 2 (dca = dicyanamide, pic = 4-picoline, biim = 2,2‘-biimidazole), have been synthesized and characterized by X-ray single-crystal structure. Complex 1 forms a one-dimensional chain where [Mn(II)(pic)₂] units are connected by double dca bridging ligands. These 1D chains interact through face-to-face Π stacking of the 4-picoline pyridine rings extending the dimensionality to a 2D supramolecular network. In complex 2 [Mn(II)(dca)(biim)] units are connected by a single dca bridging ligand to form a 1D chain of five coordinated Mn(II). The pentacoordination of Mn(II) is achieved by the bifurcated H-bond occurring between the terminal N atom of pendant dca and the two NH fragments of ligated 2,2‘-biimidazole. These chains are interlocked by cooperative hydrogen bonding and Π−Π interactions to generate (4,4) nets, which are 2-fold interpenetrated to form an interwoven 2D sheet. The variable temperature magnetic susceptibility measurements were performed, and the study reveals an antiferromagnetic interaction between the metal centers.