New insights into catalytic hydrogenation by phosphido-substituted triruthenium clusters: confirmation of intact cluster catalysis by parahydrogen NMR

Abstract

The phosphido-substituted triruthenium cluster Ru₃(CO)₉(μ-H)(μ-PPh₂) is shown to react with H₂ to form the trihydride cluster Ru₃(CO)₉(H)(μ-H)₂(μ-PPh₂), which undergoes a number of re-arrangement reactions on heating to yield other phosphido-substituted triruthenium clusters. In the presence of alkyne substrates, heating the system leads to catalytic hydrogenation via CO loss and the formation of a Ru₃(η²-PhCCHPh)(CO)₈(μ-H)(PHPh₂) resting state, in a reaction affected by the polarity of the solvent. No mononuclear fragments are observed in the catalytic transformation, confirming directly that the phosphido ligand is able to exert a stabilising influence on the cluster core.