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

The nature and the strength of intramolecular Te center dot center dot center dot N interactions in three series of o-substituted organotellurium compounds [2-(di-methyl)C6H4TeX (1a-f), 2-(oxa)C6H4TeX (2a-f), 2-(py)C6H4TeX (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 n(N) -> sigma(Te-X)* electron delocalization is the key contributing factor for Te center dot center dot center dot N non-bonding interactions. The NBO second-order perturbation energy E-Te center dot center dot center dot N (as well as NBO deletion energy E-del) correlates with Te center dot center dot center dot N distance on a single curve irrespective of the donor nitrogen atom. The values of E-Te center dot center dot center dot N (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 Te center dot center dot center dot N interactions in these compounds have a dominant covalent character. Studies on the effect of solvent on the Te center dot center dot center dot N interaction show that polar solvent stabilizes the Te center dot center dot center dot N interactions by shortening the Te center dot center dot center dot N atomic distance. Comparison with the corresponding Se counterpart shows that the strength of Te center dot center dot center dot N interactions is stronger than those of Se center dot center dot center dot N interactions. (C) 2012 Elsevier B.V. All rights reserved.