Mechanisms of the reaction between benzonitrile and 4‐octyne catalyzed by Ni(PMe3)2: A theoretical investigation

Alkali metal hydroxide-catalyzed mechanisms of Csp-H silylation of alkynes: a DFT investigation

Mechanisms for the Csp-H silylation between prop-2-yn-1-ylcyclohexane and triethylsilane, catalyzed by MOH/MH (M = Na or K), were investigated at the M06-L-D3/ma-def2-TZVP level. The SMD model was applied to simulate the solvent effect of 1,2-dimethoxyethane (DME). Computational results suggested that the Csp-H activation of prop-2-yn-1-ylcyclohexane could be achieved by MOH to generate R-CC-M compounds, which continued to react with triethylsilane to yield the final product: (3-cyclohexylprop-1-yn-1-yl) triethylsilane. Moreover, analysis of the Gibbs free energy surface of the three reactions suggested that a path with the participation of LiOH had the highest energy barrier, which was consistent with experimental results showing that only a small amount of product had been formed. The obtained KH could interact readily with the H2O molecule with a much lower energy barrier (0.6 kcal mol-1) than that using the path with prop-2-yn-1-ylcyclohexane. Furthermore, compared to MOH, MH could catalyze the reaction with lower energy barriers, and the reactions became exothermic, thereby benefiting the reaction. Finally, the mechanism for obtaining the byproduct (prop-1-yn-1-ylcyclohexane) was posited: it had a higher energy barrier than the path to yield the main product. Frontier orbital, noncovalent interactions (NCI), Fukui function and dual descriptor analyses could be used to analyze the structure and reveal the reaction substances.

DFT investigation of the DDQ-catalytic mechanism for constructing C-O bonds

In this study, we investigated the photo-catalytic mechanisms for the construction of C-O 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 3DDQ* activating the reactant (-COOH, H2O, or CH3OH) is favorable. Additionally, the role of O2 was investigated, revealing that it could facilitate the recycling of DDQ by lowering the energy barrier for the conversion of the DDQH˙ radical (not DDQH2) into DDQ. The use of ρhole and ρele 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 C-O bond formation from arenes catalyzed by DDQ.

DFT investigation on the mechanisms of Csp3–H functionalization of glycine derivatives induced by radical cation salt

The mechanism of Csp³–H functionalization between ethyl 2-(p-tolylamino)acetate and phenylethylene initiated by tris(4-bromophenyl)aminium hexachloroantimonate was elaborated based on DFT calculations.