Catalytic Alkyne Semihydrogenation with Polyhydride Ni/Ga Clusters

Angew Chem Int Ed Engl. 2023 Sep 4;62(36):e202308790. doi: 10.1002/anie.202308790. Epub 2023 Jul 28.

Abstract

The bimetallic, decanuclear Ni3 Ga7 -cluster of the formula [Ni3 (GaTMP)32 -GaTMP)33 -GaTMP)] (1, TMP=2,2,6,6-tetramethylpiperidinyl) reacts reversibly with dihydrogen under the formation of a series of (poly-)hydride clusters 2. Low-temperature 2D NMR experiments at -80 °C show that 2 consist of a mixture of a di- (2Di ), tetra- (2Tetra ) and hexahydride species (2Hexa ). The structures of 2Di and 2Tetra are assessed by a combination of 2D NMR spectroscopy and DFT calculations. The cooperation of both metals is essential for the high hydrogen uptake of the cluster. Polyhydrides 2 are catalytically active in the semihydrogenation of 4-octyne to 4-octene with good selectivity. The example is the first of its kind and conceptually relates properties of molecular, atom-precise transition metal/main group metal clusters to the respective solid-state phase in catalysis.

Keywords: (Poly-) Hydrides; Density Functional Calculations; Metal Cluster; ROESY; Semihydrogenation Catalysis.