Semi-Reduction of Internal Alkynes with Prototypical Subnanometric Metal Surfaces: Bridging Homogeneous and Heterogeneous Catalysis with Trinuclear All-Metal Aromatics

Suitably delocalized metal-metal bonds can stabilize a particular class of discrete trinuclear complexes that are the transition-metal counterparts of carbon-based aromatics. This chemical stability has pivoted the development of an advantageous catalytic method for the semireduction of internal alkynes under transfer hydrogenation condition. The reaction does not require any additional solvent and a simple workup delivers pure products. This combines with broad functional group tolerance, complete cis-selectivity and catalytic charges down to 100 ppm on multigram scale.