Two Faces of the Same Coin: Coupling X‐Ray Absorption and NMR Spectroscopies to Investigate the Exchange Reaction Between Prototypical Cu Coordination Complexes

The satisfactory rationalization of complex reactive pathways in solution chemistry may greatly benefit from the combined use of advanced experimental and theoretical complementary methods of analysis. In this work, we combine X‐Ray Absorption and 1H NMR spectroscopies with state‐of‐the‐art Multivariate Curve Resolution and theoretical analyses to gain a comprehensive view on a prototypical reaction involving the variation of the oxidation state and local structure environment of a selected metal ion coordinated by organic ligands. Specifically, we investigate the 2‐cyano‐2‐phenylpropanoic acid reduction of the octahedral complex established by the Cu2+ ion with terpyridine to the tetrahedral complex formed by Cu+ and neocuproine. Through our interdisciplinary approach we gain insights into the nature, concentration time evolution and structures of the key metal (XAS measurements) and organic (1H NMR measurements) species under reaction. We believe our method may prove to be useful in the toolbox necessary to understand the mechanisms of reactive processes of interest in solution. A detailed investigation of the reduction of the octahedral Cu(terpyridine)22+ complex to the tetrahedral Cu(neocuproine)2+ complex using the chemical fuel 2‐cyano‐2‐phenylpropanoic acid as reductant, has been carried out by exploiting an innovative mechanistic tool based on the complementarity of X‐Ray Absorption and 1H NMR spectroscopies coupled with Multivariate Curve Resolution and theoretical analys.