Experimental and Theoretical Studies of Dimers Stabilized by Two Chalcogen Bonds in the Presence of a N•••N Pnicogen Bond

The structure of the 5,6-dichloro-2,1,3-benzoselenadiazole homo-dimer, obtained by adding the ligand, 4,5-dichloro-o-phenylenediamine, to the methanolic solution of SeCl4, was determined by X-ray crystallography, augmented by Fourier transform infrared, Raman, and NMR spectroscopy. The binding motif involves a pair of Se center dot center dot center dot N chalcogen bonds, with a supplementary N center dot center dot center dot N pnicogen bond. Quantum calculations provide assessments of the strengths of the individual interactions as well as their contributing factors. All together, these three bonds compose a total interaction energy between 5.4 and 16.8 kcal/mol, with the larger chalcogen atom associated with the strongest interactions. Replacement of the Se atoms by S and Te analogues allows analysis of the dependence of these forces on the nature of the chalcogen atom. Calculations also measure the importance to the binding of the presence of a second N atom on each diazole unit as well as the substituted phenyl ring to which it is fused.

Automated summary

The crystal structure and interactions of the 5,6-dichloro-2,1,3-benzoselenadiazole homo-dimer were determined using various experimental methods, including X-ray crystallography, Fourier transform infrared, Raman, and NMR spectroscopy. The key binding motifs involve Se and Pnictogen bonds, with quantum calculations providing insights into their strengths and contributing factors. The study also analyzed the impact of replacing Se atoms with S and Te analogues, as well as the importance of secondary N atoms and substituted phenyl rings to the binding process.