An Air‐Stable Molybdenum‐Based Precatalyst in Oxygen‐Atom Transfer Reactions

• Published in: European journal of inorganic chemistry 2018-03, Vol.2018 (12), p.1427-1434
• Main Authors: Oheix, Emmanuel, Orio, Maylis, Giorgi, Michel, Réglier, Marius, Iranzo, Olga, Hardré, Renaud Y.
• Format: Article
• Language: English
• Subjects: Biomimetic models; Catalysis; Chemical Sciences; Coordination chemistry; Enzyme catalysis; Inorganic chemistry; Molybdenum; NMR; NMR spectroscopy; Nuclear magnetic resonance; Organic chemistry; Reduction; Spectrum analysis
• ISSN: 1434-1948; 1099-0682
• DOI: 10.1002/ejic.201701410

We report on the preparation and characterization of two new air‐stable mononuclear molybdenum(VI) complexes, termed MoVIO2(OPNO)2 (1) and MoVIO2(SPNO)2 (2). The potential of these complexes to act as functional mimics of molybdoenzymes from the DMSO reductase family was investigated. Initial catalytic studies suggest that 2 (but not 1) catalyzes the reduction of a sulfoxide into the thioether derivative. Studying the catalytic intermediates by UV/Vis spectroscopy, NMR spectroscopy, and DFT indicates that the active species (SPNO)2OMoV–O–MoVO(SPNO)2 (4), a dinuclear molybdenum(V) dimer with one µ‐oxo bridge, is formed upon successive reduction of the (SPNO)– ligands and the molybdenum(VI) ion. Two new complexes of bis‐oxo‐molybdenum have been prepared and investigated in oxygen transfer reactions. Mo(OPNO)2O2 is inactive in this reaction under our conditions. In contrast, Mo(SPNO)2O2 can act as a (pre)catalyst in this reaction. On the basis of the combined theoretical and spectroscopic results, a mechanism is proposed involving a µ‐oxo MoV dimer.