On the analysis of X-ray absorption spectra for polyoxometallates

[Display omitted] •Theoretical analysis of the X-ray spectral changes of polyoxometalates occurring upon reduction.•Super-reduced state of Keggin polyoxometalate leads to formation of 9 Mo-Mo bonds.•Deep Neural Network combined with molecular dynamics used to interpret fine structural changes. A detailed theoretical analysis is performed on the X-ray absorption spectral changes occurring when a Keggin-type polyoxometalate is reduced. Our analysis demonstrates that reduction by 24 electrons leads to the formation of 3 metal triangles containing 9 Mo-Mo bonds; lower than previously reported. By combining molecular dynamics (MD) simulations with a deep neural network (DNN) for predicting X-ray absorption near edge structure (XANES) spectra, we are able to reproduce the trends observed in the experimental spectra and therefore provide insight into the fine structural changes during the initial reduction steps.