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Excited-state Wolff rearrangement reaction of 5-diazo Meldrum’s acid: An ab initio on-the-fly nonadiabatic dynamic simulation

Abstract

The global switching on-the-fly trajectory surface hopping dynamic simulation at 3SA-CASSCF(12,11)/6-31G* quantum level has been employed to probe photo-induced Wolff rearrangement (WR) reaction of 5-diazo Meldrum’s acid (DMA) within three low-lying electronic excited states. The present simulation predicted that branching ratios for relaxing back to ground state, isomerizing to diazirine, and reaction to ketene I via carbene I are 69%±0.1, 3%±0.4, and 28%±0.1 in excellent agreement with femtosecond spectroscopy experiment as 67%, 3% and 30%, respectively. Especially, the present simulation revealed that major WR reaction to ketene I pathway is stepwise via excited-state to carbene I (17.8%±0.2) and via ground-state to carbene I (8.7%±0.2), and minor pathway is concerted synchronous (1.5%±0.6). Photo-induced WR reaction of DMA has be quantitatively interpreted in terms of distribution of extended seam surfaces as function of CN dissociation bond for two important conical intersections within three low-lying electronic excited states. Ultrafast dynamic time constants have been estimated as about 500fs±120fs and 180fs±80fs for stepwise and concerted WR reaction to ketene I which are also in good agreement with experiment. Therefore, photo-induced excited-state WR reaction mechanism has been quantitatively revealed by the present real-time dynamic simulation.

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Publication details

The article was received on 01 Jul 2018, accepted on 07 Aug 2018 and first published on 07 Aug 2018


Article type: Paper
DOI: 10.1039/C8CP04164D
Citation: Phys. Chem. Chem. Phys., 2018, Accepted Manuscript
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    Excited-state Wolff rearrangement reaction of 5-diazo Meldrum’s acid: An ab initio on-the-fly nonadiabatic dynamic simulation

    C. xu, F. L. Gu and C. Y. Zhu, Phys. Chem. Chem. Phys., 2018, Accepted Manuscript , DOI: 10.1039/C8CP04164D

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