# Easing Intermediates Search by Combining Spectroscopy and Multivariate Curve Reconstruction: [CuI(6,6′-dimethyl-2,2′-bipyridyl)2]PF6 Oxidation as Case Study

## TL;DR

This paper uses spectroscopy and data analysis to study copper complex oxidation, revealing new insights into reaction intermediates.

## Contribution

The study introduces a novel integration of spectroscopy and multivariate analysis to characterize oxidation intermediates in a copper complex.

## Key findings

- Two distinct CuII species were identified through oxidation of the CuI complex.
- EPR and UV–vis spectroscopy combined with MCR provided pure spectral features and concentration profiles.
- Quantum chemistry computations supported hypotheses about the CuII species structures.

## Abstract

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.