A Quantum chemical study on the potential energy surface of Mg(1S)+N2O reaction

The singlet (1A′) potential energy surface (PES) of the Mg+N2O reaction has been studied at both MP2/6-311+G∗ and CCSD(T)/6-311+G∗ levels. Two kinds of reaction channels have been identified: the first one is when the Mg atom approaches N2O in a perpendicular fashion (⌊Mg–O–N≈90.0°) and the second is when Mg approaches from the end-on (oxygen side) of N2O (⌊Mg–O–N≈148.0°). The CCSD(T) activation barrier for the perpendicular approach is 48.8 kJ/mol and compares well with the experimentally determined value (44.3±1.3 kJ/mol). The transition structure for the end-on approach has higher energy barrier, 95.7 kJ/mol. Charges analysis and electron density calculations by atoms-in-molecule theory showed that the reaction mechanism is controlled by covalent interactions between the Mg atom and the O end of N2O rather than by an electron transfer from the Mg atom to the N2O molecule.