Density Functional Theory Studies of Bonding in Complexes H₃N···XY of Ammonia and Dihalogen Molecules: A Comparison with Experimental Results from Rotational Spectroscopy

Abstract

The electron density and nuclear quadrupole coupling constants (NQCC) of the H 3 N XY (n a type in Mulliken notation) complexes, (X, Y = F, Cl, Br and I), are analyzed with the aid of density functional calculations. To demonstrate the quality of the calculations, various bond lengths and NQCCs obtained by using the hybrid Becke-Lee-Perdew-Yang functional are compared with the corresponding experimental values determined from rotational spectroscopy. An analysis of the NQCC values and various quantities derived from the natural bond orbital approach reveals that the molecular interaction is mainly electrostatic, with probably only a small extent of intermolecular electric charge redistribution on complex formation.

Thermodynamic and Spectroscopic Scales of Halogen‐Bond Basicity and Affinity

“…Theoretical [27][28][29][30][31] and experimental [10] investigations of the halogen bond show that, like the hydrogen bond, it is predominantly electrostatic in origin. However, because of the greater number of electrons around the halogens than around the hydrogen, polarization [32] and dispersion [33] forces contribute more to the halogen bond than to the hydrogen bond.…”

“…30 Family-dependent correlations between diiodine basicity and the blue shift of the visible diiodine band. a Ph 2 S was excluded from the correlation owing to its polyfunctionality.…”