The spectrum from van der Waals to donor-acceptor bonding

Area of Science:

• Chemical Physics
• Quantum Chemistry
• Materials Science

Background:

• Understanding chemical bonding is fundamental to chemistry.
• Lewis acid-base interactions are crucial in various chemical processes.
• The distinction between covalent and noncovalent bonding can be ambiguous.

Purpose of the Study:

• To quantum chemically explore the chemical bond between halogenated borane Lewis acids and Lewis bases.
• To propose a unified picture of chemical bonding across a continuum.
• To investigate the role of covalent interactions in Lewis acid-base complexes.

Main Methods:

• Dispersion-corrected relativistic density functional theory (DFT) calculations.
• Utilizing ZORA-BLYP-D3(BJ)/TZ2P level of theory.
• Examining interactions with Lewis bases of varying strengths (NH3, MeCN, N2).

Main Results:

• A bonding continuum observed, transitioning from van der Waals to donor-acceptor interactions.
• An intermediate regime identified with both van der Waals and donor-acceptor characteristics.
• A ubiquitous covalent component found across the bonding spectrum.

Conclusions:

• The stability of Lewis acid-base complexes depends on the strength of the interaction.
• Lewis pairs can be classified as strongly or weakly bonded based on covalent interaction strength.
• This work clarifies the nuanced boundaries within chemical bonding.