DFT investigation of the DDQ-catalytic mechanism for constructing CO bonds

• Published in: Organic & biomolecular chemistry Vol. 22; no. 18; pp. 3693 - 377
• Main Authors: Zheng, Xiu-Fang, Zhou, Da-Gang, Yang, Li-Jun
• Format: Journal Article
• Published: 08.05.2024
• ISSN: 1477-0520; 1477-0539
• DOI: 10.1039/d4ob00346b

In this study, we investigated the photo-catalytic mechanisms for the construction of CO bonds from arenes (benzene, 2,6-dimethyl-[1,1-biphenyl]-2-carboxylic acid, or 2,4-dichloro-1-fluorobenzene), catalyzed by 2,3-dichloro-5,6-dicyano- p -benzoquinone (DDQ). All the structures for the Gibbs free surfaces were calculated at the M06-2X-D3/ma-def2-SVP level in the SMD solvent model. Also, TDDFT calculations of DDQ were performed at the PBE1PBE-D3/ma-def2-SVP level in the SMD solvent model. The computational results indicated that DDQ, serving as a photo-catalyst, would be excited under visible light of 450 nm, aligning well with experimental observations as reflected in the UV-vis spectrum. Gibbs free energy surface analyses of the three reactions suggested that the path involving 3 DDQ* activating the reactant (COOH, H 2 O, or CH 3 OH) is favorable. Additionally, the role of O 2 was investigated, revealing that it could facilitate the recycling of DDQ by lowering the energy barrier for the conversion of the DDQH&z.rad; radical (not DDQH 2 ) into DDQ. The use of hole and ele can reveal the photo-catalytic reaction and charge transfer processes, while localized orbital locator isosurfaces and electron spin density isosurface graphs were employed to analyze structures and elucidate the single electron distribution. These computational results offer valuable insights into the studied interactions and related processes, shedding light on the mechanisms governing CO bond formation from arenes catalyzed by DDQ. The DDQ-catalytic mechanisms for constructing CO bonds via H 2 O and CH 3 OH as oxygen sources have been investigated with DFT.