Natural Bond Orbital Analysis of the Bonding in Complexes of Li with Ammonia
Author Affiliations
- 1 Laboratoire de Chimie Analytique, de Radiochimie et d’Electrochimie (LACARE), UFR/SEA 03 BP 7021 Université de Ouagadougou, BURKINA FASO
Res.J.chem.sci., Volume 4, Issue (1), Pages 20-25, January,18 (2014)
Abstract
The gas phase interactions of lithium with ammonia are studied by the DFT/B3LYP method. The calculated dissociation energies to Li and NH3 of theoptimized tetrahedral complexes Li(NH3)4 and Li(NH3)4 are 57.7 and 127.4 kcal.mol-1 with the 6-31G(d,p) basis set and show that they are stable compounds. Addition of diffuse functions on Li leads to 65.9 kcal.mol-1 for Li(NH . Natural Bond Orbital analysis of the bonding of Li and Li with the ligands has been done by computing the second order perturbation energy. One finds that the interactions that stabilize these complexes involve delocalization of charge from the lone pairs of the NH molecules into Rydberg orbitals of the metal. Then for Li(NH, a backwards donation of charge from the singly occupied orbital of Li to the Rydberg orbitals of N and H and to the N-H is observed The results also show Wiberg bond indices of 0.135 and 0.177 for the Li-N bonds in Li(NH3)4 and Li(NH3)4+ respectivelywhich suggest that they are not covalent. These systems may be described as strong van der Waals complexes of Lewis acid-Lewis base type.
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