Easing intermediates search by combining spectroscopy and multivariate curve reconstruction: [cuI(6,6′-dimethyl-2,2′-bipyridyl)2]PF6 oxidation as case study

Despite their prevalence in catalysis, complex reaction mixtures are not trivial to investigate and disentangle. Different approaches can be applied to characterize them, even featuring low-dimensionality data sets. The liquid-phase reaction of [CuI(6,6′-dimethyl-2,2′-bipyridyl)2]PF6 (CuI) with tert-butyl hydroperoxide is investigated: two CuII species are found upon oxidation of the pristine complex, characterized by different spectroscopic and kinetics fingerprints. Coupling EPR and UV-vis spectroscopies with chemometric methods (namely, multivariate curve reconstruction, MCR) allowed for easily retrieving pure spectral features and concentration profiles. Spectrokinetic analysis independently showed an optimal agreement with kinetic outcomes from MCR. Finally, hypotheses on the nature of the CuII species are drawn on the basis of EPR fitting and quantum chemistry computations on a series of candidate structures. Beyond the accurate characterization of a model system, this study demonstrates the potential of coupling multivariate statistical techniques, experiments, and computations toward a quantitative understanding of electronic and kinetic information on complex chemical systems.