Gold(I) Complex with a Photoactive Ligand Behaves as a Two-in-One Dual Metallaphotoredox Cross-Coupling Catalyst

Abstract

We herein describe the use of a gold complex with a naphthalene-di-imide-functionalized N-heterocyclic carbene (NDI-NHC) ligand, which was used as a photocatalyst for a variety of reactions. Due to the presence of the naphthalene moiety in the ligand, the complex can be used for the photogeneration of singlet oxygen, behaving as a photocatalyst in the endoperoxidation and peroxidation of cyclic and acyclic alkenes, and also in the selective oxidation of a simulant of sulfur mustard to its related nontoxic sulfoxide. The same complex was used as catalyst for two model oxidative C–C coupling reactions, namely, the coupling of aryldiazonium salts with alkynylsilanes and with mesitylene. These two catalytic reactions are a good indication that the (NDI-NHC)-Au(I) complex can behave as an effective dual metallophotoredox catalyst but with the particular feature that both the photosensitizer and the metal catalyst are contained in the same compound, thus constituting a very rare type of a “two-in-one” metallophotoredox catalyst. The participation of the Au(I)/Au(III) couple in the catalytic process was demonstrated by the isolation of a Au(III) complex, which was obtained via a self-photoactivated photoredox reaction.