Structural and theoretical study of π-stacking interactions in new complexes based on CuCl2 and 3-sulfonamide-substituted imidazo[2,1-b]thiazoles

At present, sulfonamides and their metal complexes have received a new impetus for development. Of particular interest is the study of molecular and crystal structures, which takes into account weak non-valent interactions. Despite the low energy of such interactions, in many cases, they act collectively, and the sum of their actions can play a significant role. As a result, the spectrum of medical and biological activity of new metal complexes is expanded. In this regard, the synthesis and study of the molecular and crystal structure of sulfonamides and their metal complexes is of undoubted relevance. In this work, we studied non-valent intra- and intermolecular interactions in ligands of sulfonamide-substituted imidazo[2,1-b]thiazoles and their previously unknown complexes with CuCl2. The performed analysis of the data obtained by X-ray diffraction analysis made it possible to establish the intramolecular π-stacking interaction in imidazothiazole ligands, which is retained in their complexes with CuCl2. Within the framework of QTAIM topological analysis of electron density and DORI analysis, stereoelectronic and topological structures were studied. In the complexes, tetral, chalcogen, and pnycogen new interligand non-valent interactions were established. The energies of all established types of non-valent interactions have been calculated, and their comparative evaluation has been made. X-ray data of new arylsulfonylamino-substituted derivatives of imidazo[2,1-b]thiazoles and their metal complexes with CuCl2 have been studied. To determine the theoretical prerequisites for the occurrence of π-stacking in the molecules under study, the QTAIM method was used in the framework of the DFT/B3LYP/6–311 + G(d) calculation using the GAUSSIAN 09 program. In addition, the DORI electron density region overlap indicator and the Multiwfn program were used to analyze non-valent interactions.