Crystal structure of poly[tetra-μ-chlorido-tetra-chlorido-bis-(μ3-4,4'-bi-1,2,4-triazole-κ3 N 1: N 2: N 1')(μ-4,4'-bi-1,2,4-triazole-κ3 N 1: N 1')tetra-copper(II)]

Abstract

The title Cu²⁺-chloride coordination polymer with the 4,4'-bi-1,2,4-triazole ligand (btr), [Cu₄Cl₈(C₄H₆N₆)₃] _n , crystallizes in the non-centrosymmetric ortho-rhom-bic space group Fdd2. The two independent Cu²⁺ cations adopt distorted square-pyramidal geometries with {Cl₂N₂+Cl} coordination polyhedra. The metal atoms are bridged by μ-Cl anions forming left- and right-handed helical chains of sequence [-(μ-Cl)CuCl-] _n along the c-axis direction. In the perpendicular directions, the btr ligands act in μ- and μ ₃- coordination modes in a 2:3 ratio. The μ-btr bridges connect neighboring helices of the same handedness, whereas the μ ₃-btr ligands link the helices of opposite handedness, leading to a racemic three-dimensional framework. The structure is consolidated by weak C-H⋯Cl and C-H⋯N inter-actions.

Keywords: 4,4′-bi-1,2,4-triazole; copper(II) complexes; crystal structure; metal–organic frameworks.