Isolation of a Reactive Tricoordinate α‐Oxo Gold Carbene Complex

• Published in: Angewandte Chemie International Edition Vol. 57; no. 5; pp. 1306 - 1310
• Main Authors: Zeineddine, Abdallah, Rekhroukh, Feriel, Sosa Carrizo, E. Daiann, Mallet‐Ladeira, Sonia, Miqueu, Karinne, Amgoune, Abderrahmane, Bourissou, Didier
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 26.01.2018; Wiley-VCH Verlag
• Edition: International ed. in English
• Subjects: bidentate ligand; carbene complexes; Carbenes; Catalysis; Chelation; Chemical Sciences; Crystal structure; Crystallography; diazo compounds; Gold; homogeneous catalysis; Ligands; Phenols; gold; homogeneous catalysis; diazo compounds; bidentate ligand; carbene complexes
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201711647

The [(P,P)Au=C(Ph)CO2Et]+ complex 3 [where (P,P) is an o‐carboranyl diphosphine ligand] was prepared by diazo decomposition at −40 °C. It is the first α‐oxo gold carbene complex to be characterized. Its crystallographic structure was determined and DFT calculations have been performed, unraveling the key influence of the chelating (P,P) ligand. The gold center is tricoordinate and the electrophilicity of the carbene center is decreased. Complex 3 mimics transient α‐oxo gold carbenes in a series of catalytic transformations, and provides support for the critical role of electrophilicity in the chemoselectivity of phenol functionalization (O−H vs. C−H insertion). Positive identification: For the first time, an α‐oxo gold carbene has been experimentally authenticated, providing useful insight into the factors influencing the structure, stability, and reactivity of the transient species. It features a chelating (P,P) ligand, a tricoordinate Au center, and enhanced Au→Ccarbene backdonation.