Prediction of the standard potentials for one-electron oxidation ofN,N,N′,N′ tetrasubstitutedp-phenylenediamines by calculation

Abstract

The formal potentials for the reversible one-electron oxidation of N,N,N',N' tetrasubstituted p-phenylenediamines in acetonitrile have been applied as test set for benchmarking computational methods for a series of compounds with...

A Combined Experimental and Theoretical Study of ESR Hyperfine Coupling Constants for N,N,N’,N’-Tetrasubstituted p-Phenylenediamine Radical Cations

“…Such large changes suggest that strained compounds are more sensitive to how electron correlation is treated compared to non-strained compounds, as one might have expected. However, the large changes attained from going to MP2 do not improve on the quality of correlation as was the case in the previous study of redox potentials related to such N,N,N’,N’ -tetrasubstituted p -phenylenediamines [ 2 ].…”

“…These strained fragments were also deemed problematic in the calculation of oxidation potentials in a related article [ 2 ], yet it was observed that a higher-level electronic structure model treated such outliers appropriately, thus improving results significantly. In this article, a similar approach is trialled to improve DFT results by using a slightly more sophisticated model such as MP2.…”

“…In this present work, we present experimental ESR parameters including 10 g tensor values and 64 hfccs for 11 N,N,N’,N’ -tetrasubstituted p -phenylenediamines obtained by in situ EPR/UV–vis–NIR spectroelectrochemical measurements. In addition, we report hfcc results for a series of DFT calculations aiming to determine a computational protocol suitable for reproducing experimental hfccs (similar to our previous study of N,N,N’,N’ - tetrasubstituted p -phenylenediamine redox potentials [ 2 ]). In principle, N,N,N’,N’ -tetrasubstituted p -phenylenediamines are optimal for ESR experimental investigations [ 20 ] as ESR-signals are observed only for radical species.…”

“…A chemically interesting group of molecules that are an exception to this fact are persistent N,N,N’,N’ -tetrasubstituted p -phenylenediamine radical cationic species, the redox properties of which have been explored in detail [ 2 , 3 ]. Applications include materials for solar cells [ 4 , 5 ], artificial photosynthesis [ 6 , 7 , 8 ], and organic molecular conductors [ 9 ], to name a few.…”

“…At the B3LYP/6-31G(d,p) level of theory, hyperfine coupling constants (hfccs) were underestimated by 5–8%, with progress stunted since. Recently, this molecular test set was expanded, and the redox properties [ 2 , 11 ] have been studied in great detail. Substantial progress has been made in the measurement of formal redox potentials with computational analysis verifying experimental potentials with high confidence.…”