Gold(III)-Substituted Carbenes

The Au(III)-substituted diazo compounds (N^C^C)AuC(N2)R (R = Dmp = 2,6-dimesitylphenyl and SiMe3) 1 and 6 were synthesized by reacting the (N^C^C)AuCl
precursor with the corresponding lithiated diazo compounds. Dinitrogen
extrusion was then promoted by UV–vis irradiation. The (N^C^C)Au–C–Dmp
carbene 3 undergoes intramolecular C–H insertion
followed by β-H elimination, affording a phenanthrene derivative
and the Au(III) hydride complex (N^C^C)AuH. Steric shielding prevents
intermolecular carbene trapping. The related (N^C^C)Au–C–SiMe3 carbene 7 was generated and characterized by in crystallo photolysis. In solution, it displays intermolecular
reactivity typical for triplet as well as singlet carbenes, such as
H atom abstraction and carbene-type couplings with isocyanides. DFT
calculations shed light on the structure, bonding, and reactivity
of these Au(III)-substituted carbenes.