Photochemically generated reactive sites at ruthenium/gallium complexes: catalysis vs . cluster growth.

Irradiation of [Ru(GaCp*) 3 (SiEt 3 )H 3 ] (1) at 350 nm induces reductive elimination of dihydrogen and triethylsilane and generates unsaturated Ru/Ga species. This photochemically induced cascading reductive elimination processes generate the reactive intermediate [Ru(GaCp*) 3 ], which can be trapped by diphosphine coordination to yield the stable complex [(dppe)Ru(GaCp*) 3 ] (4). The photochemically generated RuGa 3 species is catalytically active in the hydrogenation of alkynes, which is further investigated by 1 H NMR and mass spectrometry. Formation of intermetallic Ru/Ga clusters is observed as a competing and for the catalytic activity of the species limiting side reaction.