Polymorphism in the metal–organic hybrid (PhCH2NEt3)2[CoBr4]: Synthesis, crystal structures and physico-chemical characterizations

Two polymorphs of the new complex (C13H22N)2[CoBr4] have been prepared. The crystal structures of the polymorphs were determined by X-ray crystallography. Polymorph I belongs to the triclinic system, space group P-1 (No 2), while polymorph II adopts the monoclinic space group P21/c (No 14). The crystal packing is guided by Csingle bondH···Br hydrogen bonds; these interactions contribute to the overall stabilization of the structures as they connect anions and cations together into a three-dimensional network. The polymorphs present different structure-properties relationships. Hirshfeld surfaces analysis contributes to the identification of the primary intermolecular contacts that guide the packing diagram. The thermal decomposition was studied by DSC, VT-PXRD, TDA and TGA techniques. The optical band gap energy suggests the semiconductor nature of the polymorphs. Temperature dependent magnetic susceptibility measurements in the temperature range of 1.8–310 K reveal that the polymorphs exhibit very weak antiferromagnetic interactions or contributions from single ion anisotropy