Local Proton Source in Electrocatalytic CO2 Reduction with [Mn(bpy–R)(CO)3Br] Complexes. Issue 20 (22nd February 2017)

• Record Type: Journal Article
• Authors: Franco, Federico; Cometto, Claudio; Nencini, Luca; Barolo, Claudia; Sordello, Fabrizio; Minero, Claudio; Fiedler, Jan; Robert, Marc; Gobetto, Roberto; Nervi, Carlo
• Is Part Of: Chemistry. Volume 23:Issue 20(2017)
• Page Start: 4782
• Page End: 4793
• Publication Date: 2017-02-22
• Subjects: carbon dioxide -- density functional calculations -- electrocatalysis -- electrochemistry -- manganese; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201605546
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: The electrochemical behavior of fac ‐[Mn(pdbpy)(CO)3 Br] (pdbpy=4‐phenyl‐6‐(phenyl‐2, 6‐diol)‐2, 2′‐bipyridine) (1 ) in acetonitrile under Ar, and its catalytic performances for CO2 reduction with added water, 2, 2, 2‐trifluoroethanol (TFE), and phenol are discussed in detail. Preparative‐scale electrolysis experiments, carried out at −1.5 V versus the standard calomel electrode (SCE) in CO2 ‐saturated acetonitrile, reveal that the process selectivity is extremely sensitive to the acid strength, producing CO and formate in different faradaic yields. A detailed spectroelectrochemical (IR and UV/Vis) study under Ar and CO2 atmospheres shows that1 undergoes fast solvolysis; however, dimer formation in acetonitrile is suppressed, resulting in an atypical reduction mechanism in comparison with other reported Mn I catalysts. Spectroscopic evidence of Mn hydride formation supports the existence of different electrocatalytic CO2 reduction pathways. Furthermore, a comparative investigation performed on the new fac ‐[Mn(ptbpy)(CO)3 Br] (ptbpy=4‐phenyl‐6‐(phenyl‐3, 4, 5‐triol)‐2, 2′‐bipyridine) catalyst (2 ), bearing a bipyridyl derivative with OH groups in different positions to those in1, provides complementary information about the role that the local proton source plays during the electrochemical reduction of CO2 . Abstract : Acid‐induced selectivity : The electrochemical behavior of fac ‐[Mn(pdbpy)(CO)3 Br] (pdbpy=4‐phenyl‐6‐(phenyl‐2, 6‐diol)‐2, 2′‐bipyridine) in MeCN under Ar and its catalytic performances for CO2 reduction with added water, 2, 2, 2‐trifluoroethanol (TFE), and phenol are discussed. Bulk electrolysis reveals that the process selectivity is sensitive to the acid strength, producing CO and formate in different faradaic yields. The key role of the local proton source is demonstrated by a detailed spectroelectrochemical study under Ar and CO2 .