catena-Poly[[tetra-kis-(3,5-dimethyl-1H-pyrazole-κN (2))copper(II)]-μ(2)-sulfato-κ(2) O:O']: crystal structure and Hirshfeld surface analysis of a Cu(II) coordination polymer.

The title coordination polymer, [Cu(SO(4))(C(5)H(8)N(2))(4)] (n) , was synthesized using a one-pot reaction of copper powder, anhydrous copper(II) sulfate and 3,5-dimethyl-1H-pyrazole (Hdmpz) in aceto-nitrile under ambient conditions. The asymmetric unit can be described as a chain consisting of four [Cu(SO(4))(Hdmpz)(4)] formula units that are connected to each other by a μ(2)-sulfato-bridged ligand. The octa-hedral coordination geometry (O(2)N(4)) of all copper atoms is realized by coordination of four pyrazole ligands and two sulfate ligands. Four pyridine-like N atoms of the pyrazole ligands occupy the equatorial positions, while two oxygen atoms of two sulfate ligands are in axial positions. As a result of the sulfate ligand rotation, there is a pairwise alternation of terminal O atoms (which are not involved in coordination to the copper atom) of the SO(4) tetra-hedra. The Cu⋯Cu distances within one asymmetric unit are in the range 7.0842†(12)-7.1554†(12)†à . The crystal structure is built up from polymeric chains packed in a parallel manner along the b-axis direction. Hirshfeld surface analysis suggests that the most important contributions to the surface contacts are from H⋯H (74.7%), H⋯O/O⋯H (14.8%) and H⋯C/C⋯H (8.2%) inter-actions.