Salophen and salen oxo vanadium complexes as catalysts of sulfides oxidation with H2O2: Mechanistic insights

The application of V(V) catalysts in oxidation of sulfides with peroxides offers an efficient procedure, that is compatible with different functional groups, and leads to good yields and selectivities. However, the understanding of the factors affecting the reactivity of different catalysts is still far to be complete. An experimental and theoretical study on a series of V(V) complexes containing variously substituted salen and salophen ligands is reported with the aim to correlate the activity of the catalysts with the electronic character of the vanadium center. The results obtained indicate that steric factors play a major role in determining the outcome of the reaction, often overcoming the electronic effects. Theoretical results suggest the intervention in the catalytic cycle of an hydroperoxo vanadium species.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (84 K)Download as PowerPoint slideHighlights► Substituted salen and salophen V(V)O complexes as oxidation catalysts. ► Electronic and steric substituent effects determine the outcome of the reaction, with the latter playing a major role. ► The nature of actual catalyst investigated by 51V NMR remained unclear. ► Theoretical calculations suggest the preferential formation of V(V)O hydroperoxidic species.