![Sample our Mathematics & Statistics journals, sign in here to start your FREE access for 14 days]({"type":"image" , "src" : "/sda/5943/TOC-Subject-Sample-2021-Mathematics-Statistics.jpg"})
Abstract
The diazocarbene radical, CNN, and the ions CNN+ and CNN− were investigated at a high level of theory. Very accurate structural parameters for the states X 3Σ− and A 3Π of CNN, and X 2Π of both CNN+ and CNN− were obtained with the UCCSD(T) method using correlated-consistent basis functions with extrapolations to the complete basis set limit, with valence only and also with all electrons correlated. Harmonic and anharmonic frequencies were obtained for all species and the Renner parameter and average frequencies evaluated for the Π states. At the UCCSD(T)/CBST-5 level of theory, Δf H(0 K) = 138.89 kcal/mol and Δf H(298 K) = 139.65 kcal/mol were obtained for diazocarbene; for the ionization potential and the electron affinity of CNN, 10.969 eV (252.95 kcal/mol), and 1.743 eV (40.19 kcal/mol), respectively, are predicted. Geometry optimization was also carried out with the CASSCF/MRCI/CBST-5 approach for the states X 3Σ−, A 3Π, and a 1Δ of CNN, and with the CASSCF/MRSDCI/aug-cc-pVTZ approach for the states b 1Σ+, c 1Π, d 1Σ−, and B 3Σ−, and excitation energies (Te) evaluated. Vertical energies were calculated for 15 electronic states, thus improving on the accuracy of the five transitions already described, and allowing for a reliable overview of a manifold of other states, which is expected to guide future spectroscopic experiments. This study corroborates the experimental assignment for the vertical transition X 3Σ− ← E 3Π.
Acknowledgements
F.R.O. acknowledges the research support from Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP), as well as a research productivity fellowship sponsored by the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) of Brazil. T.V.A. also acknowledges FAPESP for a graduate fellowship, and Y.A.A. is thankful to CNPq for a graduate fellowship.