Theoretical Study of closo-Borate Anions [BnHn]2- (n=5-12): Bonding, Atomic Charges, and Reactivity Analysis

This study has focused on the structure, bonding, and reactivity analysis of closo-borate anions [BnHn](2-) (n = 5-12). Several descriptors of B-H interactions have been calculated. It has been found that the values of electron density and total energy at bond critical point are the most useful descriptors for investigation of B-H interactions. Using results from the descriptor analysis, one may conclude that orbital interactions in [BnHn](2-) increase with increasing the boron cluster size. Several approaches to estimate atomic charges have been applied. Boron atoms in apical positions have more negative values of atomic charges as compared with atoms from equatorial positions. The mean values of boron and hydrogen atomic charges tend to be more positive with the increasing of boron cluster size. Global and local reactivity descriptors using conceptual density functional theory (DFT) theory have been calculated. Based on this theory, the closo-borate anions [BnHn](2-) (n = 5-9) can be considered strong and moderate electrophiles, while the closo-borate anions [BnHn](2-) (n = 10-12) can be considered marginal electrophiles. Fukui functions for electrophilic attack have been calculated. Fukui functions correlate well with atomic charges of the closo-borate anions. Boron atoms in apical positions have the most positive values of Fukui functions.

Automated summary

This study focused on the analysis of structure, bonding, and reactivity of closo-borate anions [BnHn](2-) (n = 5-12). It was found that descriptors like electron density and total energy at bond critical point are useful for investigating B-H interactions. Orbital interactions in [BnHn](2-) were observed to increase with boron cluster size. Atomic charges of the boron atoms were found to vary with their positions, with boron atoms in apical positions having more negative values. Global and local reactivity descriptors were calculated, showing [BnHn](2-) (n = 5-9) to be strong and moderate electrophiles, while [BnHn](2-) (n = 10-12) were marginal electrophiles. Fukui functions for electrophilic attack were also computed, with boron atoms in apical positions having the most positive values.