Photo-redox coupled Co-pincer complexes for efficient decarbonylation of aryl carbonyls: A quantum chemical investigation

Abstract

Abstract Catalytic decarbonylation of aryl carbonyls is a challenging task. Although some precious metal based catalysts have been developed, Earth abundant transition metal based decarbonylating catalysts are yet to be realized. Very recently, Co(I) pincer complex has been utilized for one step decarbonylation of aromatic and aliphatic aldehydes, however, the reactions do not proceed for the next step catalytic cycle. To address this issue, we here present the thermodynamic and mechanistic aspects of the reactions and on the basis of first principles calculations, we shed some light for further developing the catalyst. We demonstrate that it is the thermodynamic factor that inhibits the catalytic activity due to very strong metal-carbonyl interactions. However, a similar Co(II) complex shows much less regeneration energy but fails to initiate the reaction. We propose that if a suitable Ru(II)/Ir(III) photo sensitizer is used, the resultant photoredox catalytic system coupled with the Co(II) pincer complex might be very efficient for the decarbonylation process.