Open AccessCarboxylate Structural Effects on the Properties and Proton-Coupled Electron Transfer Reactivity of [CuO2CR]2+ Cores
Author(s) -
Courtney E. Elwell,
Mukunda Mandal,
Caitlin J. Bouchey,
Lawrence Que,
Christopher J. Cramer,
William B. Tolman
Publication year - 2019
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.9b02293
Subject(s) - chemistry , electron transfer , reactivity (psychology) , ligand (biochemistry) , carboxylate , redox , proton , metal , proton coupled electron transfer , crystallography , electron , medicinal chemistry , stereochemistry , computational chemistry , photochemistry , inorganic chemistry , organic chemistry , medicine , biochemistry , physics , alternative medicine , receptor , pathology , quantum mechanics
A series of complexes {[NBu 4 ][LCu II (O 2 CR)] (R = -C 6 F 5 , -C 6 H 4 (NO 2 ), -C 6 H 5 , -C 6 H 4 (OMe), -CH 3 , and -C 6 H 2 ( i Pr) 3 )} were characterized (with the complex R = -C 6 H 4 (m-Cl) having been published elsewhere ( Mandal et al. J. Am. Chem. Soc. 2019 , 141 , 17236 )). All feature N,N',N″ -coordination of the supporting L 2- ligand, except for the complex with R = -C 6 H 2 ( i Pr) 3 , which exhibits N,N',O -coordination. For the N,N',N″ -bound complexes, redox properties, UV-vis ligand-to-metal charge transfer (LMCT) features, and rates of hydrogen atom abstraction from 2,4,6,-tri- t -butylphenol using the oxidized, formally Cu(III) compounds LCu III (O 2 CR) correlated well with the electron donating nature of R as measured both experimentally and computationally. Specifically, the greater the electron donation, the lower is the energy for LMCT and the slower is the reaction rate. The results are interpreted to support an oxidatively asynchronous proton-coupled electron transfer mechanism that is sensitive to the oxidative power of the [Cu III (O 2 CR)] 2+ core.