par Liévin, Jacques 
;Verhaegen, Georges
Référence Theoretica chimica acta, 45, 4, page (269-281)
Publication Publié, 1977-12
;Verhaegen, Georges Référence Theoretica chimica acta, 45, 4, page (269-281)
Publication Publié, 1977-12
Article révisé par les pairs
| Résumé : | The least-energy dissociation path of the ground state of CH2N2 was determined from ab initio calculations using in a complementary way basis sets of minimal size (STO-3G) and double-zeta (DZ) quality. The results indicate that the least-energy point of attack of the N2 molecule on CH2 (1A1) is roughly perpendicular to the molecular plane (93 °), the C and N atoms being almost co-linear (angle C-N-N:203 ° with outermost N atom pointing away from CH2). The potential barrier of ∼ 1.2 eV found previously on the C2v dissociation path, disappears completely along the least-energy dissociation path (point group Cs (out-of-plane)). These findings corroborate the Woodward-Hoffman rules for this process since the outermost orbitals of the two intersecting states found in point group C2v (...2 b1 and ...8 a1) both correlate to the same irreducible representation (10 á) in point group Cs (out-of-plane). Larger basis set calculations (DZ + polarization functions on all centers, 3 dc and 3 dN developed here), were also carried out on CH2N2 (1A1,3A2 and1A2) at the1A1 equilibrium geometry and on CH2 (3B1) and N2 (1Σg+) at their respective equilibrium geometries. These calculations, together with consideration of correlation energy differences, yield D00 (CH2N2,1A1) = 19 kcal/mole and vertical excitation energies of 67 and 73 kcal/mole for the3A2 and1A2 states respectively. The latter value is in good agreement with the measured experimental value: 72.4 kcal/mole corresponding to the maximum of intensity in the1A2←1A1 absorption band. © 1977 Springer-Verlag. |
