Theoretical study on the noncovalent interactions involving triplet diphenylcarbene.

The properties of some types of noncovalent interactions formed by triplet diphenylcarbene (DPC3) have been investigated by means of density functional theory (DFT) calculations and quantum theory of atoms in molecule (QTAIM) studies. The DPC3···LA (LA = AlF3, SiF4, PF5, SF2, ClF) complexes have been analyzed from their equilibrium geometries, binding energies, and properties of electron density. The triel bond in the DPC3···AlF3 complex exhibits a partially covalent nature, with the binding energy - 65.7 kJ/mol. The tetrel bond, pnicogen bond, chalcogen bond, and halogen bond in the DPC3···LA (LA = SiF4, PF5, SF2, ClF) complexes show the character of a weak closed-shell noncovalent interaction. Polarization plays an important role in the formation of the studied complexes. The strength of intermolecular interaction decreases in the order LA = AlF3 > ClF > SF2 > SiF4 > PF5. The electron spin density transfers from the radical DPC3 to ClF and SF2 in the formation of halogen bond and chalcogen bond, but for the DPC3···AlF3/SiF4/PF5 complexes, the transfer of electron spin density is minimal.