Triel Bonds with Au Atoms as Electron Donors

Abstract The novel triel bonds of BX 3 (X=H, F, Cl, Br, and I) and C 5 H 5 B as electron acceptors and AuR 2 (R=Cl and CH 3 ) as an electron donor were explored. The triel bond is a primary driving force for most complexes, while the contribution from a halogen‐chlorine interaction in BX 3 −AuCl 2 (X=Cl, Br, and I) and an iodine‐Au interaction in BI 3 −Au(CH 3 ) 3 is also very important. Interestingly, the positively charged Au atom of AuCl 2 can attractively bind with the holes of BX 3 and C 5 H 5 B. The interaction energy lies in the range of 1 and 80 kcal/mol, in the order X=F<H<Cl<Br<I. In most cases, the triel bond of C 5 H 5 B is stronger than the triel bond of BX 3 . In the formation of B−Au triel bond, electrostatic energy is not dominant, while polarization energy including orbital interaction has the largest contribution for the strongly bonded complexes and dispersion energy for the weak triel bond.