Boosting catalyst activity in cis-selective semi-reduction of internal alkynes by tailoring the assembly of all-metal aromatic tri-palladium complexesElectronic supplementary information (ESI) available: Reaction procedures, characterization of complexes, copies of NMR spectra. See DOI: 10.1039/c6dt01840h

Highly symmetric [Pd 3 ] + clusters that present delocalized metal-metal bonds can catalyse the selective semi-reduction of internal alkynes to cis -alkenes. Studies on factors governing the formation of all-metal aromatics enabled the design of an optimised catalytic system that delivers cis -alkenes with almost complete selectivity on a gram scale with very low catalyst loadings (0.03 mol%). Zwitterionic all-metal aromatic tri-palladium complexes can catalyse the cis -selective semi-reduction of internal alkynes at ppm levels.