Theoretical Insights into the Nature of Halogen Bonding in Prereactive Complexes

Abstract

Benchmark quality geometries and interaction energies for the prereactive halogen-bonded complexes of dihalogens and ammonia, including hypothetical astatine containing dihalogens, have been produced via explicitly correlated coupled cluster methods. The application of local electron correlation partitioning reveals dispersion, electrostatics and ionic substitutions all contribute significantly to the interaction energy, with a linear relationship between the ionic substitutions and the degree of charge transfer. Potential energy curves for H3N⋅⋅⋅ClF show that as the relative orientations of the two subunits are manipulated appreciable interactions can be found at considerably angular displaced geometries, signifying lower directionality in halogen bonding than previously supposed.

A Computational Study of Chalcogen‐containing H2X…YF and (CH3)2X…YF (X=O, S, Se; Y=F, Cl, H) and Pnicogen‐containing H3X′…YF and (CH3)3X′…YF (X′=N, P, As) Complexes

“…For example, matrixisolation IR spectroscopic work on NH 3 …F 2 , [23] PH 3 …F 2 [24] and AsH 3 …F 2 [25] has been reported, as well as for the interaction of ClF and Cl 2 with H 2 Se, (CH 3 ) 2 Se and AsH 3 . [28] Two recent articles, providing a general framework for the definition and understanding of noncovalent s-hole interactions such as tetrel, pnicogen and chalcogen bonding, appeared last year, [29,30] while the most extensive review of halogen bonding, thus far, appeared in 2016. [28] Two recent articles, providing a general framework for the definition and understanding of noncovalent s-hole interactions such as tetrel, pnicogen and chalcogen bonding, appeared last year, [29,30] while the most extensive review of halogen bonding, thus far, appeared in 2016.…”

“…[36][37][38][39][40][41][42] The effect of other types of intermolecular interactions in pnicogen-bonded complexes has also been studied. [28,48] In the present study, we find that the difference in electronegativity of the X and Y atoms of the model H 2 X…YF and (CH 3 ) 2 X…YF (X=O, S, Se; Y=F, Cl, H) and H 3 X'…YF and (CH 3 ) 3 X'…YF (X'=N, P, As) complexes is useful in rationalizing the energetic trends obtained, especially the anomalous stability of some complexes of F 2 . [48] In the present study, we consider two measures of the interaction energy for our model complexes, one which takes into account the deformation energy (i. e. the energy required to deform the monomer subunits from their equilibrium geometries to the geometries they adopt in the optimized complex) and one which does not.…”

The halogen bond in thiirane⋯ClF: an example of a Mulliken inner complex

“…This is consistent with the NBO charge transfer previously found for the H 3 NÁ Á ÁXY complexes. 7 The charge transfer on formation of the thiiraneÁ Á ÁClF complex is much more significant as it is roughly a factor of five greater, indicating that it plays a more important role in the mechanism of the interaction in this case. What is striking from the individual atomic natural charges (also known as NPA charges) is that the thiirane sulfur possesses a fractional positive charge in both cases, whereas the oxirane oxygen is fractionally negative.…”

Some Interesting Features of Non-Covalent Interactions

“…The subject of halogen bonding is very active, [46][47][48][49] and cannot been covered, even briefly, in a review like the present one. For this reason and because this is an original approach of our research, we will summarize the part concerning indirect spin-spin coupling constants (SSCC) in halogen-bonded complexes.…”