Hydrogen bonding as a probe of electron densities: limiting gas-phase nucleophilicities and electrophilicities of B and HX

Rotational spectra and properties of complexes B⋯ICF3 (B = Kr or CO) and a comparison of the efficacy of ICl and ICF3 as iodine donors in halogen bond formation

“…It has been shown in Refs. 2 and 3 that k σ values for several series of complexes B· · ·XY (and, earlier, for many B· · ·HX) 45 can be predicted with reasonable accuracy by means of the expression…”

A further exploration of a nucleophilicity index based on the gas-phase ionization potentials

“…Later on, the explicit consideration of additional factors contribute to rationalize a better quantitative description of nucleophilicity [10,11]. Legon and Millen [12] proposed an experimental model to probe the gas-phase nucleophilicities and electrophilicities in hydrogen-bonded B-HX dimers, where B is the nucleophile and HX is the electrophile, using the low-frequency hydrogen bond stretching modes as a measure of the nucleophilicity power. The model has been successfully applied to several nucleophilic systems [13].…”

A DFT Study of the Reactivity Indexes of Ionic [4 + 2+] Diels-Alder Cycloaddition to Nitrilium and Immonium Ions

“…In a formal framework it has allowed introducing in a many empirical chemical concepts like electronegativity [10], hardness [11], so-called reaction force [12], Fukui function [13], electrophilicity [14], electrofugality and nucleofugality [1,2,9,[15][16][17][18], nucleophilicity and solution phase ionization potentials, homofugality [19,20], nucleophilicity [21], among others. In particular, the introduction of concepts like electrophilicity and nucleophilicity to define electron deficient (electrophile) and electron rich (nucleophile) species has gained a continuous interest to construct empirical scales classifying atoms, molecules and charged species [22][23][24][25][26][27][28][29]. The availability of empirical scales of electrophilicity and nucleophilicity, usually based on kinetic parameters, has been very useful to rationalize the chemical reactivity, in terms of selectivity, reaction mechanisms, solvent, substituent effects, etc.…”