title: Mechanistic insight into conjugated N-N bond cleavage by Rh(III)-catalyzed redox-neutral C-H activation of pyrazolones.
abstract: Density functional theory (DFT) calculations have been performed to investigate the detailed mechanism of Rh(III)-catalyzed redox-neutral C-H activation of pyrazolones with PhC≡CPh. It is found that (1) the methylene C-H activation is prior to the phenyl C-H activation, (2) the N-N bond cleavage is realized via Rh(III) → Rh(I) → Rh(III) rather than via Rh(III) → Rh(V) → Rh(III). The zwitterionic Rh(I) complex is identified to be a key intermediate in promoting the N-N bond cleavage. (3) Different from the Rh(III)-catalyzed hydrazine-directed C-H activation for indole synthesis, the rate-determining step of the reaction studied in this work is the Rh(III) → Rh(I) → Rh(III) process resulting in the N-N bond cleavage rather than the alkyne insertion step. The present theoretical study provides new insight into the mechanism of the conjugated N-N bond cleavage.
authors.affiliation: College of Chemistry and Chemical Engineering, Qufu Normal University, Qufu 273165, P. R. China. siweibi@126.com liuyuxia2008@163.com.
authors.forename: Weirong
authors.initials: W
authors.lastname: Wu
authors.forename: Yuxia
authors.initials: Y
authors.lastname: Liu
authors.forename: Siwei
authors.initials: S
authors.lastname: Bi
mesh_terms: D002384:Catalysis; D008968:Molecular Conformation; D010084:Oxidation-Reduction; D047069:Pyrazolones / Q000737:chemistry*; D012238:Rhodium / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry; D013816:Thermodynamics
chemical_list: D047069:Pyrazolones; D012997:Solvents; D012238:Rhodium