Carbon dioxide capture from air leading to bis-[ N -(5-methyl-1 H -pyrazol-3-yl-κ N 2 )carbamato-κ O ]copper(II) tetra-hydrate.

A mononuclear square-planar Cu II complex of (5-methyl-1 H -pyrazol-3-yl)carbamate, [Cu(C 5 H 6 N 3 O 2 ) 2 ]·4H 2 O, was synthesized using a one-pot reaction from 5-methyl-3-pyrazolamine and copper(II) acetate in water under ambient conditions. The adsorption of carbon dioxide from air was facilitated by the addition of di-ethano-lamine to the reaction mixture. While di-ethano-lamine is not a component of the final product, it plays a pivotal role in the reaction by creating an alkaline environment, thereby enabling the adsorption of atmos-pheric carbon dioxide. The central copper(II) atom is in an (N 2 O 2 ) square-planar coordination environment formed by two N atoms and two O atoms of two equivalent (5-methyl-1 H -pyrazol-3-yl)carbamate ligands. Additionally, there are co-crystallized water mol-ecules within the crystal structure of this compound. These co-crystallized water mol-ecules are linked to the Cu II mononuclear complex by O-H⋯O hydrogen bonds. According to Hirshfeld surface analysis, the most frequently observed weak inter-molecular inter-actions are H⋯O/O⋯H (33.6%), H⋯C/C⋯H (11.3%) and H⋯N/N⋯H (9.0%) contacts.