Abstract
The interaction between molybdenum, atom, and dimer, with nitrous oxide has been investigated using density functional theory. The analysis of the potential energy surfaces for both reactions has revealed that a single molybdenum atom can activate the NO bond of N~2~O requiring a small activation energy. However, the presence of several intersystem crossings between three different spin states, namely, septet, quintet and triplet states, seems to be the major constraint to the Mo + N~2~O reaction. Contrarily, the low‐lying excited states (triplet and quintet) do not participate in the reaction between the molybdenum dimer and N~2~O. The latter reaction fully evolves on the singlet spin surface. Three different regions have been distinguished along the pathway: formation of an adduct complex, formation of an inserted compound, and the N~2~ detachment. The connection between the two first regions has been characterized by the formation of a special complex in which the NO bond is so weakened that it could be considered as a first step in the insertion process. It has been shown that the topological changes along the pathways provide a clear explanation for the geometrical changes that occur along the reaction pathway. In summary, the detachment of the N~2~ molecule is found to be kinetically an effective process for both reactions, owing to the high exothermicity and consequently to the high internal energy of the insertion intermediates. However, in the case of Mo atom, the reaction should be a slow process due to the presence of spin‐forbidden transitions. These results fully agree with previous experimental works. © 2005 Wiley Periodicals, Inc. J Comput Chem 26: 1284–1293, 2005