Towards operando IR‐ and UV‐vis‐Spectro‐Electrochemistry: A Comprehensive Matrix Factorisation Study on Sensitive and Transient Molybdenum and Tungsten Mono‐Dithiolene Complexes

The redox sequences of sensitive aliphatic mono‐dithiolene complexes [MII(CO)2(cydt)(dppe)] (M=Mo, W) were studied with extensive cyclic voltammetrical and spectro‐electrochemical (SEC) investigations using UV‐vis and IR spectroscopy. With a newly developed matrix factorisation technique, the pure component spectra and temporal evolution of the developed species were ascertained, including sensitive and transient ones. The concentration of all involved compounds at the working electrode as dependent on the respective applied potential was derived with very high accuracy. The assignment of the species’ geometries and electronic structures was further verified by quantum chemical calculations. Overall, the combined electrochemical, spectroscopic, quantum chemical and mathematical approach facilitates a comprehensive understanding of the underlying electrochemical transformations and equilibria. Since only a single CV run is needed to obtain all data required to identify the individual species, the method presented here is expected to be applicable to a wide range of complicated electrochemically responsive systems and thus opens a path towards developing a deeper mechanistic understanding of the underlying chemistry. An approach for the extraction of pure component UV‐vis and IR spectra of transient species from a single CV run using a matrix factorisation technique is presented. Conformational changes and ligand exchange reactions are detected, as exemplified with a series of sensitive tungsten and molybdenum mono‐dithiolene complexes. This method is easily combined with computational chemistry and applicable to a wide range of molecular compounds.