Synthesis, Crystal Structure, and Magnetic Behavior of Two Dicyanamido-Bridged Complexes of Manganese(II): Effect of Weak Interaction in Carving Regular Geometry

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.