Influence of N-Base and O-Base Hybridization on Triel Bonds

The complexes of TrR₃ (Tr = B and Al; R = H, F, Cl, and Br) with three N-bases (NH₃, CH₂NH, and HCN) and three O-bases (CH₃OH, H₂CO, and CO) are utilized to explore the hybridization effect of N and O atoms on the strength, properties, and nature of the triel bond. The sp-hybridized O and N atoms form the weakest triel bond, followed by the sp²-hybridized O atom or the sp³-hybridized N atom, and the sp³-hybridized O atom or the sp²-hybridized N atom engages in the strongest triel bond. The hybridization effect is also related to the substituent of TrR₃. Most complexes are dominated by electrostatic, with increasing polarization contribution from sp to sp² to sp³. Although the CO oxygen engages in a weaker triel bond, its carbon atom is a better electron donor and the interaction energy even amounts to -37 kcal/mol in the BH₃ complex.