Exploring the Reaction Paths on the Potential Energy Surfaces of the S 1 and T 1 States in Methylenecyclopropane
| Autor: | Toshio Asada, Shiro Koseki, Nozomi Sawada, Mamoru Haruta |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
Physics
010304 chemical physics Cyclobutene General Medicine 010402 general chemistry Methylenecyclopropane 01 natural sciences Biochemistry Potential energy Molecular physics Transition state 0104 chemical sciences chemistry.chemical_compound Vibronic coupling chemistry 0103 physical sciences Physical and Theoretical Chemistry Triplet state Ground state Carbene |
| Zdroj: | Photochemistry and Photobiology. 97:126-135 |
| ISSN: | 1751-1097 0031-8655 |
| Popis: | The reaction paths of methylenecyclopropane 1 on the potential energy surfaces (PESs) of the lowest triplet (T1 ) state and the lowest excited singlet (S1 ) state, as well as that of the ground state (S0 ), were explored by using the nudged elastic band method at the MRMP2//MCSCF/6-31++G(d,p) and DFT(B3LYP)/6-31++G(d,p) levels of theory. After vertical excitation of 1, three transition states on the PES of the lowest triplet state and one transition state on the S1 PES were found along the reaction path to produce a carbene, cyclobutylidene 2. All of these transition states are lower in energy than the S1 state produced by vertical excitation at the S0 energy minimum in 1. Fast transition is predicted to occur from the T1 state or from the S1 state to the S0 state due to strong spin-orbit coupling or nonadiabatic coupling in the geometrical vicinity of 2. On the MRMP2 S0 PES, the energy barriers of 5.0, 10.3 and 13.5 kcal mol-1 were obtained for C migration reaction (backward reaction), 1,2-H migration reaction to cyclobutene 3, and 1,3-H migration reaction to bicyclopropane 4, respectively, started at 2. The introduction of phenyl groups makes the energy barriers smaller due to the π conjugation between the carbene center and phenyl groups. |
| Databáze: | OpenAIRE |
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