Synthesis, crystal structure and thermal properties of poly[[μ-1,2-bis(pyridin-4-yl)ethene-κ² N:N′-μ-bromido-copper(I)] 1,2-bis(pyridin-4-yl)ethene 0.25-solvate]

Abstract

The reaction of copper(I) bromide with 1,2-bis(pyridin-4-yl)ethene in acetonitrile leads to the formation of the title compound, {[CuBr(C12H10N2)]·0.25C12H10N2} n or CuBr(4-bpe)·0.25(4-bpe) [4-bpe = 1,2-bis(pyridin-4-yl)ethene]. The asymmetric unit consists of one copper(I) cation and one bromide anion in general positions as well as two crystallographically independent half 4-bpe ligands and a quarter of a disordered 4-bpe solvate molecule that are completed by centers of inversion. The copper(I) cations are tetrahededrally coordinated as CuBr2N2 and linked by pairs of μ-1,1-bridging bromide anions into centrosymmetric dinuclear units that are further connected into layers by the 4-bpe coligands. Between the layers, interlayer C—H...Br hydrogen bonding is observed. The layers are arranged in such a way that cavities are formed in which the disordered 4-bpe solvate molecules are located. Powder X-ray (PXRD) investigations reveal that a pure sample has been obtained. Thermogravimetric (TG) and differential thermoanalysis (DTA) measurements show two mass losses that are accompanied by endothermic events in the DTA curve. The first mass loss correspond to the removal of 0.75 4-bpe molecules, leading to the formation of (CuBr)2(4-bpe), already reported in the literature as proven by PXRD.