Abstract
We have quantum chemically investigated the bonding between archetypical Lewis acids and bases. Our state-of-the-art computations on the X3B−NY3 Lewis pairs have revealed the origin behind the systematic increase in B−N bond strength as X and Y are varied from F to Cl, Br, I, H. For H3B−NY3, the bonding trend is driven by the commonly accepted mechanism of donor−acceptor [HOMO(base)−LUMO(acid)] interaction. Interestingly, for X3B−NH3, the bonding mechanism is determined by the energy required to deform the BX3 to the pyramidal geometry it adopts in the adduct. Thus, Lewis acids that can more easily pyramidalize form stronger bonds with Lewis bases. The decrease in the strain energy of pyramidalization on going from BF3 to BI3 is directly caused by the weakening of the B−X bond strength, which stems primarily from the bonding in the plane of the molecule (σ-like) and not in the π system, at variance with the currently accepted mechanism.
| Original language | English |
|---|---|
| Pages (from-to) | 4043-4054 |
| Number of pages | 12 |
| Journal | Chemistry - An Asian Journal |
| Volume | 15 |
| Issue number | 23 |
| Early online date | 5 Oct 2020 |
| DOIs | |
| Publication status | Published - 1 Dec 2020 |
Funding
This work was supported by the Netherlands Organization for Scientific Research (NWO), the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) and the Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG). Furthermore, we thank Dr. Chris Slootweg, Asante Landbrug, Jop Meijer, and Matthijs Koning for helpful discussions.
Keywords
- Activation strain analysis
- Bond energy
- Density functional calculations
- Energy decomposition analysis
- Lewis acid-base pairs
