Nucleophilicities of Lewis Bases B and Electrophilicities of Lewis Acids A Determined from the Dissociation Energies of Complexes B⋯A Involving Hydrogen Bonds, Tetrel Bonds, Pnictogen Bonds, Chalcogen Bonds and Halogen Bonds.

Ibon Alkorta,Anthony Legon

doi:10.3390/molecules22101786

Abstract

It is shown that the dissociation energy for the process B⋯A = B + A for 250 complexes B⋯A composed of 11 Lewis bases B (N2, CO, HC≡CH, CH2=CH2, C3H6, PH3, H2S, HCN, H2O, H2CO and NH3) and 23 Lewis acids (HF, HCl, HBr, HC≡CH, HCN, H2O, F2, Cl2, Br2, ClF, BrCl, H3SiF, H3GeF, F2CO, CO2, N2O, NO2F, PH2F, AsH2F, SO2, SeO2, SF2, and SeF2) can be represented to good approximation by means of the equation , in which is a numerical nucleophilicity assigned to B, is a numerical electrophilicity assigned to A, and is a constant, conveniently chosen to have the value 1.00 kJ mol−1 here. The 250 complexes were chosen to cover a wide range of non-covalent interaction types, namely: (1) the hydrogen bond; (2) the halogen bond; (3) the tetrel bond; (4) the pnictogen bond; and (5) the chalcogen bond. Since there is no evidence that one group of non-covalent interaction was fitted any better than the others, it appears the equation is equally valid for all the interactions considered and that the values of and so determined define properties of the individual molecules. The values of and can be used to predict the dissociation energies of a wide range of binary complexes B⋯A with reasonable accuracy.

Highlights

The best known, earliest identified non-covalent interaction is the hydrogen bond, the halogen bond was discovered as long ago as 1869 through the reaction of iodine with ammonia [1]
B· · · A composed of 11 Lewis bases B and 23 Lewis acids can be represented to good approximation by means of the equation De = c0 NB EA, in which NB is a numerical nucleophilicity assigned to B, EA is a numerical electrophilicity assigned to A, and c0 is a constant, conveniently chosen to have the value 1.00 kJ mol−1 here
The 250 complexes were chosen to cover a wide range of non-covalent interaction types, namely: (1) the hydrogen bond; (2) the halogen bond; (3) the tetrel bond; (4) the pnictogen bond; and (5) the chalcogen bond

Summary

Introduction

The best known, earliest identified non-covalent interaction is the hydrogen bond, the halogen bond was discovered (but not so called) as long ago as 1869 through the reaction of iodine with ammonia [1]. Led to the recognition of the halogen bridge (the term used by Hassel for the halogen bond). This was followed by a lull in experimental work until the mid-1990s when there was a very rapid growth of interest [3,4] in what became known as the halogen bond. The chalcogen bond [7], it has been pointed out [8,9] that these types of interaction were known for at least 30 years before they were assigned their current names. Each non-covalent bond can be described [9,10] in terms of the interaction of an electrophilic region of one molecule with a nucleophilic region of another molecule (or even the same molecule).

Methods

Results

Conclusion