Premium
Nitrenes as intermediates in the thermal decomposition of aliphatic azides
Author(s) -
Arenas J. F.,
Marcos J. I.,
Otero J. C.,
Tocón I. L.,
Soto J.
Publication year - 2001
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.1326
Subject(s) - hydrazoic acid , nitrene , azide , chemistry , complete active space , singlet state , diradical , computational chemistry , thermal decomposition , ab initio , photochemistry , atomic physics , physics , excited state , density functional theory , biochemistry , organic chemistry , basis set , catalysis
Abstract N 2 extrusion from hydrazoic acid, methyl azide, and ethyl azide to yield the corresponding nitrene has been studied with high‐level ab initio calculations. Geometry optimizations of stationary points and surfaces crossing seams were carried out with the complete active space self‐consistent field (CASSCF) method, and their energies were reevaluated with the second‐order multireference perturbation (CASPT2) theory and corrected by the zero‐point energy (ZPE). The analytic harmonic frequencies calculated at the CASSCF level have been used in the ZPE corrections. The decomposition reaction is a competitive mechanism between a spin‐allowed and a spin‐forbidden channel, giving the nitrene either in the singlet or triplet states. The energy barrier height for XNN 2 bond fission is approximately the same in both channels for each azide, respectively. The spin‐orbit (H SO ) interactions were determined at the minimum energy point on the seam of crossing between the singlet and triplet surfaces, the value ranges from 43.9 cm −1 in hydrazoic acid to 43.3 cm −1 in ethyl azide. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem 84: 241–248, 2001