Site Titration with Organic Bases During Catalysis: Selectivity Modifier and Structural Probe in Methanol Oxidation on Keggin Clusters

The selective and permanent titration of protons with organic bases (2,6‐di‐ tert ‐butylpyridine or pyridine) provides an accurate measure of the dispersion of Keggin structures during catalytic oxidation of methanol. Titration allows the systematic control of the redox and acid properties of H 3+ n PV n Mo 12− n O 40 ( n =0–4) Keggin clusters and leads to unprecedented selectivity in the formation of dimethoxymethane (>80 %) and high yields.