# Quantum information-based analysis of electron-deficient bonds

## TL;DR

This paper applies quantum information theory to analyze electron-deficient bonds, successfully describing complex bonding in molecules like diborane and novel compounds with unusual bonding patterns.

## Contribution

It extends the correlation theory of chemical bonds to electron-deficient bonds, demonstrating its effectiveness on complex and recently synthesized molecules.

## Key findings

- Successfully characterized three-center two-electron bonds in diborane(6)
- Described bonding in diborane(4) and beryllium complexes with unusual stability
- Validated the correlation theory as a tool for analyzing exotic chemical bonds

## Abstract

Recently, the correlation theory of the chemical bond was developed, which applies concepts of quantum information theory for the characterization of chemical bonds, based on the multiorbital correlations within the molecule. Here for the first time, we extend the use of this mathematical toolbox for the description of electron-deficient bonds. We start by verifying the theory on the textbook example of a molecule with three-center two-electron bonds, namely the diborane(6). We then show that the correlation theory of the chemical bond is able to properly describe bonding situation in more exotic molecules which have been synthetized and characterized only recently, in particular the diborane molecule with four hydrogen atoms [diborane(4)] and neutral zerovalent s-block beryllium complex, whose surprising stability was attributed to a strong three-center two-electron $\pi$ bond stretching across the C-Be-C core. Our approach is of a high importance especially in the light of a constant chase after novel compounds with extraordinary properties where the bonding is expected to be unusual.