Bis(sulfonylimide)ruthenium(VI) Porphyrins: X‐ray Crystal Structure and Mechanism of CH Bond Amination by Density Functional Theory Calculations. Issue 34 (1st July 2013)

• Record Type: Journal Article
• Authors: Guo, Zhen; Guan, Xiangguo; Huang, Jie‐Sheng; Tsui, Wai‐Man; Lin, Zhenyang; Che, Chi‐Ming
• Is Part Of: Chemistry. Volume 19:Issue 34(2013)
• Page Start: 11320
• Page End: 11331
• Publication Date: 2013-07-01
• Subjects: Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201300021
• Languages: English
• ISSNs: 0947-6539

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>The X‐ray crystal structure of [Ru<sup>VI</sup>(NMs)<sub>2</sub>(tmp)] (Ms=SO<sub>2</sub>‐ <italic>p</italic>‐MeOC<sub>6</sub>H<sub>4</sub>; tmp=5, 10, 15, 20‐tetramesitylporphyrinato(2−)), a metal sulfonylimide complex that can undergo alkene aziridination and CH bond amination reactions, shows a RuN distance of 1.79(3) Å and Ru‐N‐S angle of 162.5(3)°. Density functional theory (DFT) calculations on the electronic structures of [Ru<sup>VI</sup>(NMs)<sub>2</sub>(tmp)] and model complex [Ru<sup>VI</sup>(NMs)<sub>2</sub>(por<sup>0</sup>)] (por<sup>0</sup>=unsubstituted porphyrinato(2−)) using the M06L functional gave results in agreement with experimental observations. For the amination of ethylbenzene by the singlet ground state of [Ru<sup>VI</sup>(NMs)<sub>2</sub>(por<sup>0</sup>)], DFT calculations using the M06L functional revealed an effectively concerted pathway involving rate‐limiting hydrogen atom abstraction without a distinct radical rebound step. The substituent effect on the amination reactivity of ethylbenzene by [Ru<sup>VI</sup>(NX)<sub>2</sub>(por<sup>0</sup>)] (X=SO<sub>2</sub>‐<italic>p</italic>‐YC<sub>6</sub>H<sub>4</sub> with Y=MeO, Me, H, Cl, NO<sub>2</sub>) was examined. Electron‐withdrawing Y groups lower the energy of the LUMOs of [Ru<sup>VI</sup>(NX)<sub>2</sub>(por<sup>0</sup>)], thus facilitating their interaction with the low‐lying HOMO of the ethylbenzene CH bond and hence increasing the reactivity of [Ru<sup>VI</sup>(NX)<sub>2</sub>(por<sup>0</sup>)]. DFT calculations on the amination/aziridination reactions of [Ru<sup>VI</sup>(NSO<sub>2</sub>C<sub>6</sub>H<sub>5</sub>)<sub>2</sub>(por<sup>0</sup>)] with pent‐4‐enal, an aldehyde substrate bearing acyl, homoallylic, and allylic CH bonds and a CC bond, revealed a lower reaction barrier for the amination of the acyl CH bond than for both the amination of the other CH bonds and aziridination of the CC bond in this substrate.</p> </abstract>