Structure of inorganic compounds halogen bonds in derivatives of 2,5-diiod-1,4-dimethylbenzene

Abstract

The synthesis of 1,4-di(bromomethyl)-2,5-diiodo-benzene (1), diacetate of 2,5-diiodo–1,4-di(hydroxymethyl)benzene (2) and diiodide of 1,1’-[(2,5-diiodo-1,4-phenylene)bis(methylene)]dipyridinium (3) is described and their crystallographic data are given. All three crystal structures are characterized by the stacked packing of planar molecules and the presence of halogen bonds I–Br, I–O, and I–I, respectively. The number of halogen bonds is maximum in compound 1: two I–Br bonds for each halogen atom. Compounds 2 and 3 contain one halogen bond per halogen atom, but they are significantly shorter than in compound 1. All crystals were investigated by IR spectroscopy and synchronized thermal analysis. Compound 1, which has no ionic or hydrogen bonds, melts at a higher temperature than ionic compound 3 (218 and 200°C, respectively) due to the presence of a large number of intermolecular halogen bonds. Compound 2 melts at a lower temperature (151°C), which is characteristic of esters.