Triel Bonding Interactions in Lewis Acid Complexes

Triel bonding denotes a class of noncovalent interactions in which an electron-deficient centre belonging to group 13 elements (boron, aluminium, gallium and their congeners) engages with an electron-rich moiety. Analogous to more familiar hydrogen and halogen bonds, triel bonds exploit regions of positive electrostatic potential (σ- or π-holes) on the triel atom and are highly directional. Their strength is governed primarily by electrostatic attraction, but substantial contributions arise from charge transfer, dispersion forces and orbital interactions. Geometrical parameters often reflect a balance between retention of the trigonal planar configuration at the triel centre and distortion towards a pyramidal or tetrahedral arrangement upon complexation. These interactions underpin key processes in catalysis, molecular recognition and materials assembly. At a global level, precise tuning of substituents on the Lewis acid partner enables modulation of bond strength over a wide energy range, offering routes to superacid systems, controlled proton transfers and novel organometallic frameworks. Advanced quantum-chemical analyses—including energy decomposition schemes, the natural bond orbital method and quantum theory of atoms in molecules—have elucidated the interplay between electrostatics and covalency within triel bonds, broadening our capacity to design functional supramolecular architectures.

Research from Nature Portfolio

No recent Nature Portfolio content available.

Triel Bonding Interactions in Lewis Acid Complexes publication trend

The graph below shows the total number of articles in triel bonding interactions in lewis acid complexes across all publications each year (not limited to Nature Index journals).

Technical terms

Triel bond: an attractive noncovalent interaction between a group 13 element centre and an electron-rich site.

Lewis acid: an electron-pair acceptor, often a metal centre or element with an empty orbital.

σ-hole: a region of positive electrostatic potential along the extension of a covalent bond, enabling directional noncovalent interactions.

π-hole: an electron-deficient area above or below a molecular plane arising from electron-withdrawing substituents, facilitating bonding to π-electron donors.

References

1. Ga···C Triel Bonds—Why They Are Not Strong Enough to Change Trigonal Configuration into Tetrahedral One: DFT Calculations on Dimers That Occur in Crystal Structures. International Journal of Molecular Sciences (2023).
2. Triel Bonds between BH3/C5H4BX and M(MDA)2 (X = H, CN, F, CH3, NH2; M = Ni, Pd, Pt, MDA = Enolated Malondialdehyde) and Group 10 Transition Metal Electron Donors. Molecules (2024).
3. Triel Bond Formed by Malondialdehyde and Its Influence on the Intramolecular H-Bond and Proton Transfer. Molecules (2022).