On the Importance of Noncovalent Carbon-Bonding Interactions in the Stabilization of a 1D Co(II) Polymeric Chain as a Precursor of a Novel 2D Coordination Polymer

A new cobalt­(II) coordination polymer 2 with μ_1,5 dicyanamide (dca) and a bidentate ligand 3,5-dimethyl-1-(2′-pyridyl)­pyrazole (pypz) is prepared in a stepwise manner using the newly synthesized one-dimensional linear Co­(II) coordination polymer 1 as a precursor. The structural and thermal characterizations elucidate that the more stable complex 2 shows a two-dimensional layer structural feature. Here, Co­(II) atoms with μ_1,5 dicyanamido bridges are linked by the ligand pypz forming a macrocyclic chain that runs along the crystallographic ‘c’ axis having ‘sql’ (Shubnikov notation) net topology with a 4-connected uninodal node having point symbol {4⁴.6²}. The remarkable noncovalent carbon-bonding contacts detected in the X-ray structure of compound 1 are analyzed and characterized by density functional theory calculations and the analysis of electron charge density (atoms in molecules).