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

Abstract

The structure of the 5,6-dichloro-2,1,3-benzoselenadiazole homodimer, 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···N chalcogen bonds, with a supplementary N···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.

Principles Guiding the Square Bonding Motif Containing a Pair of Chalcogen Bonds between Chalcogenadiazoles

“…This work also verified that the benzo ring has only a minor influence upon the binding between the two diazole units. It is gratifying that the DFT data described above are confirmed by the MP2 means of incorporating correlation on some similar systems.…”

“…The idea that the two N atoms on diazole units might form a stabilizing interaction with one another was broached in a very recent work in which the diazoles were placed on substituted benzene units, mimicking experimentally derived structures . Like the systems described here, the presence of a N···N AIM bond path was present for the thio- and seleno-substituted diazoles, but not for Te.…”

Exploring Supramolecular Assembly Space of Cationic 1,2,4-Selenodiazoles: Effect of the Substituent at the Carbon Atom and Anions

“…[ 13 , 14 , 15 , 16 ]. Chalcogenodiazoles have gained particular interest within ChB research and have been extensively studied in recent years in the context of their applications in anion recognition and as supramolecular building blocks [ 6 , 17 , 18 , 19 , 20 , 21 ].…”

Noncovalent Bonds through Sigma and Pi-Hole Located on the Same Molecule. Guiding Principles and Comparisons

“…Quite the opposite from representing exotic or unusual contacts, these bonds make important contributions to numerous fields of chemistry and biology. As examples, understanding the forces behind crystal engineering and supramolecular chemistry benefits from a knowledge of σ-hole interactions due to their directionality, strength, and selforganization properties which promote formation of adducts in the solid state [34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52]. The importance of σ-hole bonding has also been verified in the context of anion recognition processes [53][54][55][56][57][58][59][60][61], materials chemistry [62][63][64][65][66][67][68][69][70][71][72], or biochemistry [73][74][75][76][77][78][79]…”