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 μ1,5 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 μ1,5 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).