# Stabilization of [(N5)2BX]2– and [(N5)2B2X2]2– (X = H, F, Cl, Br) by Conjugation and Hyperconjugation Effects

## TL;DR

This paper explores how boron compounds can be stabilized using conjugation and hyperconjugation effects, suggesting new catalysts for eco-friendly chemical processes.

## Contribution

The study identifies borinium anions [(N5)2BH]2− and [(N5)2B2H2]2− as potential catalysts stabilized by π-conjugation and hyperconjugation.

## Key findings

- π-conjugation and hyperconjugation stabilize anionic boron compounds [(N5)2BX]2– and [(N5)2B2X2]2–.
- Hydrogen substituents (X = H) provide the most stabilization through delocalized π-bonding.
- Borinium anions [(N5)2BH]2− and [(N5)2B2H2]2− are proposed as novel environmentally friendly catalysts.

## Abstract

The isolation of
nucleophilic boron bases has led to a paradigm
shift in boron chemistry. Previous studies of the bis(carbene) borylene
complexes revealed that these compounds possess strong donor abilities,
and their reaction inertness is due to the large steric hindrance
between boron reagents and reactant. In the present study, we have
theoretically studied the [(N5)2BX]2– and [(N5)2B2X2]2– compounds (X = H, F, Cl, Br). Their electronic structures
and properties are discussed by using the NBO, LOL, and ELF methods.
We found that both π-conjugation and hyperconjugation effects
can effectively stabilize the substituted nucleophilic anionic boron
compounds [(N5)2BX]2– and
[(N5)2B2X2]2–. Substituents, especially X = H, stabilize the boron center through
highly delocalized π-bonding, involving the formally “empty”
in-plane p orbitals of the boron atom. While the
halogen substituents have high electron withdrawal ability, leading
to systems being less stable, we suggest the borinium anions [(N5)2BH]2– and [(N5)2B2H2]2– as possible
synthetic targets of novel environmentally friendly catalysts.

Among the eight compounds of the [(N5)2BX]2− and [(N5)2B2X2]2− (X = H, F,
Cl, Br), the borinium
anions [(N5)2BH]2− and [(N5)2B2H2]2− are identified as potential synthetic targets of innovative environmentally
friendly catalysts.