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oai:riuma.uma.es:10630/172942026-02-03T12:09:19Zcom_10630_2254col_10630_37959

An MS-CASPT2 Study of the Photodecomposition of 4- Methoxyphenyl Azide. Role of Internal Conversion and Intersystem Crossing Aranda Ruiz, Daniel Ávila-Ferrer, Francisco José López-Tocón, Isabel Arenas Rosado, Juan Francisco Otero-Fernández-de-Molina, Juan Carlos Soto-Martín, Juan Fotoquímica Aryl azides photochemistry is strongly dependent on the substituent relative position, as has been studied by time resolved resonant Raman (TR3) spectroscopy for 4-methoxyphenyl azide and its isomer 3-methoxyphenyl azide. When irradiated at 266 nm, the former results in 4,4’-dimethoxyazobenzene whereas the latter forms 1,2-didehydroazepine. It is proposed that the key step of the reactions is the formation of a nitrene derivative. Recently, it has been proposed by us that nitrenes might have a relevant role in the Surface-Enhanced Raman Scattering (SERS) of p-aminothiophenol, however, the molecular mechanism is not well known in neither of these cases. Therefore, we studied the photodecomposition of 4-methoxyphenyl azide using multiconfigurational self-consistent field methods (MC-SCF) with the CAS-SCF and MS-CASPT2 approximations and calculated the resonant Raman spectra of the relevant species using a multi-state version of Albrecht’s vibronic theory. The results propose that the reaction follows a two steps sequence after irradiation at 266 nm: an intersystem crossing 21A’/23A’’ which decays through a 21A’/21A’’ conical intersection producing molecular nitrogen and triplet 4-methoxyphenyl nitrene in its ground state. 2019-02-13T08:03:45Z 2019-02-13T08:03:45Z 2019-02-13 conference output https://hdl.handle.net/10630/17294 eng Symposium on π-Computing p-conjugated compounds (CπC-10) Valencia (España) 1-2 Febrero 2019 http://creativecommons.org/licenses/by-nc-nd/4.0/ open access Attribution-NonCommercial-NoDerivatives 4.0 Internacional