Framework solids based on copper(II) halides (Cl/Br) and methylene-bridged bis-(1-hydroxybenzotriazole): synthesis, crystal structures, magneto-structural correlation, and density functional theory (DFT) studies

A methylene-bridged 1-hydroxybenzotriazole derived ligand L [L = 1, 3-bis(benzotriazol-1-yl)-1,3-dioxapropane] has been synthesized and characterized by spectroscopic and structural methods. Reaction of L with two different copper(II) halides [CuX2; X = Br, Cl] in an identical condition yields two different compounds of similar compositions, {[Cu(μ-Br)(Br)(μ-L)]2}n·2nH2O (1) and {[Cu(μ-Cl)(Cl)(μ-L)]2}n·2nH2O (2), both being characterized by various physicochemical techniques. Single crystal X-ray studies reveal that they appear as 2D coordination polymers with similar bridging fashion of L. Low temperature magnetic susceptibility measurements reveal antiferromagnetic and ferromagnetic behaviors for 1 and 2 with magnetic coupling constants J = −15.2 and +1.7 cm–1, which are in a reasonable agreement with their calculated values (J = −9.79 and +0.68 cm–1 respectively, for 1 and 2). The role of bridging halides in the structure and magnetic properties of the complexes are investigated, and a possible magneto-structural correlation has been established. Influence of spin density of bridging halides on the magnitude of coupling constants has been discussed with the help of density functional theory (DFT) calculations.