Nature of the TeN intramolecular interaction in organotellurium compounds. A theoretical investigation by NBO and AIM methods

摘要

The nature and the strength of intramolecular Ten interactions in three series of o-substituted organotellurium compounds [2-(di-methyl)C _6H _4TeX (1a-f), 2-(oxa)C _6H _4TeX (2a-f), 2-(py)C _6H _4TeX (3a-f); X=Cl, Br, Me, CN, SPh and TePh; Me: Methyl, Ph: Phenyl] have been studied using density functional theory. The effect of substituents (X) and different nitrogen donors are predicted using B3LYP/LanL2DZ method. The Natural Bond Orbital (NBO) analysis demonstrated that the nN→σTeX* electron delocalization is the key contributing factor for TeN non-bonding interactions. The NBO second-order perturbation energy E TeN (as well as NBO deletion energy E _(del)) correlates with Te;N distance on a single curve irrespective of the donor nitrogen atom. The values of E _(TeN) (as well as E del) approximately follow the trend Br>Cl>TePh>SPh>CN>Me for a given nitrogen donor, and 3>2>1 for a given X. Both NBO and Atoms-in-Molecule (AIM) methods suggest that the TeN interactions in these compounds have a dominant covalent character. Studies on the effect of solvent on the TeN interaction show that polar solvent stabilizes the TeN interactions by shortening the TeN atomic distance. Comparison with the corresponding Se counterpart shows that the strength of TeN interactions is stronger than those of SeN interactions.