Molecular Catalysts with Intramolecular Re-O Bond for Electrochemical Reduction of Carbon Dioxide

A new Re bilayridirie-type complex, namely, fac-Rembpy)(CC))3C1 (pmbpy = 4-pheny1-6-(2-hydroicy-falieny1)-2,2'-bipyridine), 1, carrying a single OH moiety; as local proton source, has been synthesized, and its electrochemical behavior under Ar and under CO2 has been characterized. Two isomers of 1, namely, 1 -cis characterized by the i.iroizirnity of CI to OH and 1 -trans, are identified. The interconversion between 1 -cis and 1 -trans is clarified by DFT calculations, which reveal. I/ two transition states. The energetically lower pathway displays a non- F negligible barrier of 75.5 kJ rno1-1. The le- electrochemical reduction of 1 affords the neutral intermediate 1-0P1-1, formally derived by reductive deprotonation and loss of Cl from 1. 1-0Ph, which exhibits ancharacterized.espectroscopicnt r Picall Y favored(Tihg, e a ndidetailedntN Em R)1e' c anduit haatc ntheelectrochemicalPuta catalyticmt ench-a2la,n6(-10 activity))'_n2af,approaches. _irebo nipacyronfieda- relativelye complexesi\, liis marebtableInR s resultinge1 odibondts iPnlatahYlowwnPsarieeT1reductionaseclecPntNI'rc-veeefvea-rieunecoe 9,r e NTienC lOn2tphenolateh thebond, has proton souce.