Electronic structure and reactivity of the CNO/NCO/CON isomers

Ab initio study of the spectroscopy of the X2Π electronic ground states of CNO and NCO

“…These negative values of A SO are in agreement with an anormal multiplet and with the previous data computed by Yazidi et al of À95.6 cm À1 for NCO and À109.6 cm À1 for CNO [12]. These values can be compared to those obtained experimentally by Patel- Misra [21].…”

“…The CON X 2 P state is not discussed in this work due to its predissociation by the 4 R À state correlating with the CO(X 2 R + ) + N( 4 S) asymptote, located approximatively 4.5 eV below its energy minimum as shown by Yazidi et al [12].…”

“…It is particularly interesting to compare the results obtained with similar calculations except a selection via a threshold in the reference wavefunction for the MRCI calculation [12]. At the MRCI level, the harmonic wavenumbers differ by as much as 40 cm À1 , and after the Davidson correction Q [18], this difference is reduced to less than 10 cm À1 .…”

“…The detailed study of the spectroscopy of the ground states of NCO and CNO is indeed complicated by the fact that these states are of 2 P symmetry and present both strong Renner-Teller and spin-orbit couplings. The results of the numerous investigations of the NCO isomer by experimentalists [5,6], completed by theoretical works [10,12] since many years, allowed us to establish a strategy to obtain the most appropriate PEFs to reproduce the experimental rovibronic energies up 4000 cm À1 above the zerovibrational energy. Moreover, the role of the basis set and of the electronic correlation on the Renner-Teller constants will be discussed for NCO for which many experimental data exist [5].…”

“…After the recent work of Yazidi et al [12], it appeared that a rovibronic spectroscopy study of the electronic ground states of NCO and CNO requires the determination of very accurate potential energy functions (PEFs). The detailed study of the spectroscopy of the ground states of NCO and CNO is indeed complicated by the fact that these states are of 2 P symmetry and present both strong Renner-Teller and spin-orbit couplings.…”