Open AccessLuminescent cis-Bis(bipyridyl)ruthenium(II) Complexes with 1,2-Azolylamidino Ligands: Photophysical, Electrochemical Studies, and Photocatalytic Oxidation of Thioethers
Author(s) -
Elena Cuéllar,
Alberto DiezVarga,
Tomás Torroba,
Pablo DomingoLegarda,
J. Alemán,
Silvia Cabrera,
Jose M. MartínÁlvarez,
Daniel Miguel,
Fernando Villafañe
Publication year - 2021
Publication title -
inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.348
H-Index - 233
eISSN - 1520-510X
pISSN - 0020-1669
DOI - 10.1021/acs.inorgchem.0c03389
Subject(s) - chemistry , ruthenium , catalysis , phosphorescence , photochemistry , acetonitrile , steric effects , electrochemistry , medicinal chemistry , nitrile , stereochemistry , organic chemistry , physics , quantum mechanics , fluorescence , electrode
New 1,2-azolylamidino complexes cis -[Ru(bipy) 2 (NH═C(R)az*-κ 2 N , N )](OTf) 2 (R = Me, Ph; az* = pz, indz, dmpz) are synthesized via chloride abstraction after a subsequent base-catalyzed coupling of a nitrile with the previously coordinated 1,2-azole. The synthetic procedure allows the easy obtainment of complexes having different electronic and steric 1,2-azoylamidino ligands. All of the compounds have been characterized by 1 H, 13 C, and 15 N NMR and IR spectroscopy and by monocrystal X-ray diffraction. Photophysical studies support their phosphorescence, whereas their electrochemistry reveals reversible Ru II /Ru III oxidations between +1.13 and +1.25 V (vs SCE). The complexes have been successfully used as catalysts in the photooxidation of different thioethers, the complex cis -[Ru(bipy) 2 (NH═C(Me)dmpz-κ 2 N , N )] 2+ showing better catalytic performance in comparison to that of [Ru(bipy) 3 ] 2+ . Moreover, the significant catalytic performance of the dimethylpyrazolylamidino complex is applied to the preparation of the drug modafinil, which is obtained using ambient oxygen as an oxidant. Finally, mechanistic assays suggest that the oxidation reaction follows a photoredox route via oxygen radical anion formation.