RT info:eu-repo/semantics/article
T1 Luminescent Rhenium(I)tricarbonyl Complexes Containing Different Pyrazoles and Their Successive Deprotonation Products: CO2 Reduction Electrocatalysts
A1 Merillas, Beatriz
A1 Cuéllar, Elena
A1 Diez Varga, Alberto
A1 Torroba Pérez, Tomás
A1 García Herbosa, Gabriel
A1 Fernández, Sergio
A1 Lloret-Fillol, Julio
A1 Martín-Alvarez, Jose M.
A1 Miguel, Daniel
A1 Villafañe, Fernando
K1 Deprotonation
K1 Diimides
K1 Electrodes
K1 Ligands
K1 Reaction mechanisms
K1 Química inorgánica
K1 Chemistry, Inorganic
AB Cationic fac-[Re(CO)3(pz*H)(pypzH)]OTf (pz*H = pyrazole, pzH; 3,5-dimethylpyrazole, dmpzH; indazole, indzH; 3-(2-pyridyl)pyrazole, pypzH) were obtained from fac-[ReBr(CO)3(pypzH)] by halide abstraction with AgOTf and subsequent addition of the corresponding pyrazole. Successive deprotonation with Na2CO3 and NaOH gave neutral fac-[Re(CO)3(pz*H)(pypz)] and anionic Na{fac-[Re(CO)3(pz*)(pypz)]} complexes, respectively. Cationic fac-[Re(CO)3(pz*H)(pypzH)]OTf, neutral complexes fac-[Re(CO)3(pz*H)(pypz)], and fac-[Re(CO)3(pypz)2Na] were subjected to photophysical and electrochemical studies. They exhibit phosphorescent decays from a prevalently 3MLCT excited state with quantum yields (Φ) in the range between 0.03 and 0.58 and long lifetimes (τ from 220 to 869 ns). The electrochemical behavior in Ar atmosphere of cationic and neutral complexes indicates that the oxidation processes assigned to ReI → ReII occurs at lower potentials for the neutral complex compared to cationic complex. The reduction processes occur at the ligands and do not depend on the charge of the complexes. The electrochemical behavior in CO2 saturated media is consistent with CO2 electrocatalyzed reduction, where the values of the catalytic activity [icat(CO2)/icat(Ar)] ranged from 2.7 to 11.5 (compared to 8.1 for fac-[Re(CO)3Cl(bipy)] studied as a reference). Controlled potential electrolysis for the pyrazole cationic (3a) and neutral (4a) complexes after 1 h affords CO in faraday yields of 61 and 89%, respectively. These values are higher for indazole complexes and may be related to the acidity of the coordinated pyrazole.
PB American Chemical Society
SN 0020-1669
YR 2020
FD 2020-07
LK http://hdl.handle.net/10259/6823
UL http://hdl.handle.net/10259/6823
LA eng
NO Spanish MINECO, Spain (PGC2018-099470–B-I00) and Junta de Castilla y León (VA130618), and the authors in Burgos gratefully acknowledge financial support from the Junta de Castilla y León, Consejería de Educación y Cultura y Fondo Social Europeo (Project BU263P18). E.C. thanks the UVa for her grant. We also thank the ICIQ Foundation, AGAUR 2017-SGR-1647 (J.L.-F.) and the Spanish MINECO (CTQ2016-80038-R; J.L-F.), and the Spanish Ministry of Science is acknowledged for a FPU fellowship to S.F.
DS Repositorio Institucional de la Universidad de Burgos
RD 23-nov-2024