Triel Bonds with Au Atoms as Electron Donors

The novel triel bonds of BX₃ (X=H, F, Cl, Br, and I) and C₅ H₅ B as electron acceptors and AuR₂ (R=Cl and CH₃ ) 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 BX₃ -AuCl₂ (X=Cl, Br, and I) and an iodine-Au interaction in BI₃ -Au(CH₃ )₃ is also very important. Interestingly, the positively charged Au atom of AuCl₂ can attractively bind with the holes of BX₃ and C₅ H₅ B. The interaction energy lies in the range of 1 and 80 kcal/mol, in the order X=F5 H₅ B is stronger than the triel bond of BX₃ . 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.