Revisiting the reactivity of Ru3(CO)12 with PhC≡CPh (diphenylacetylene)-new findings of a thermic effect towards higher nuclearity

Abstract In this paper we report tri- and tetranuclear ruthenium carbonyl compounds containing PhC≡CPh ligand showing μ 3 -η 2 , μ 3 -η 4 , μ 4 -η 2 coordination modes. A one-pot reaction between [Ru 3 (CO) 12 ] and PhC≡CPh in THF (tetrahydrofuran) at 66 °C gave the new trinuclear compound [Ru 3 (CO) 6 (μ-CO) 2 (μ 3 -η 4 -C 4 Ph 4 )] ( 2 ) in 30% yield together with the previously reported [Ru 3 (CO) 8 (μ 3 -η 2 -C 2 Ph 2 ) 2 ] ( 1 ) in 25% yield. Compound 1 converts to 2 under refluxing condition in THF. A similar reaction involving [Ru 3 (CO) 12 ] with PhC≡CPh in refluxing benzene (80 ° C) afforded previously reported closo -tetraruthenium compounds [Ru 4 (CO) 12 (μ 4 -η 2 -C 2 Ph 2 )] ( 3 ) and [Ru 4 (CO) 10 (μ-CO)(μ 4 -η 2 -C 2 Ph 2 ) 2 ] ( 4 ) in 25 and 16% yields, respectively along with 2 in 20% yields. Compounds 1 , 2 and 4 were characterized by single-crystal X-ray diffraction analysis in addition to IR and 1 H NMR spectroscopic methods.