Gold-Manganese Bimetallic Redox Coupling with Light.

ABSTRACT

The classical Au(I)/Au(III) redox couple chemistry has been limited to constructing C-C and C-X bonds, and thus, the exploration of the elementary reaction of gold redox coupling is very significant to enrich its organometallic features. Herein, we report the first visible-light-mediated, external oxidant-free Au(I)/Au(III) redox couple using commercially available Mn2(CO)10 to generate Mn-Au(III)-Mn intermediates for bimetallic redox coupling. A wide range of structurally diverse heterodinuclear and polynuclear L-Au(I)-Mn-L' complexes (19 examples, up to >99% yields) are readily constructed, providing a robust strategy for the concise construction of Au-Mn complexes under mild reaction conditions. The mechanistic studies together with DFT calculations support the radical oxidative addition of •Mn(CO)5 to gold and bimetallic reductive elimination mechanisms from highly active Mn-Au(III)-Mn species, representing an important step toward an elementary reaction in gold chemistry research. Furthermore, the resulting Au-Mn complexes exhibit unique catalytic activity, with which divergent reductive coupling of nitroarenes can readily afford azoxybenzenes, azobenzenes, and hydrazobenzenes in moderate to good yields.