Triel bonds-complexes of boron and aluminum trihalides and trihydrides with benzene

Triel bond is an interaction of an atom of the 13th Group of periodic system that acts as a Lewis acid with an electron rich species; it is analyzed here in complexes of benzene with boron and aluminum trihalides and trihydrides. MP2/aug-cc-pVTZ calculations were performed for these complexes and the interactions were analyzed with the use of Quantum Theory of Atoms in Molecules. It was found that benzene acts as the Lewis base not through a pi-electron system but through one of carbon centers that is characterized by the most negative charge if compared with other carbon atoms of benzene. Thus, the BaEuro broken vertical bar C and AlaEuro broken vertical bar C bond paths are analyzed which correspond to preferable interactions; for some of complexes, the additional halogen (X)-carbon, XaEuro broken vertical bar C, intermolecular bond paths exist.