Catalytically Reactive Ruthenium Intermediates in the Homogeneous Oxidation of Alcohols to Esters

Ru(η 4 ‐tetracyclone)(CO) 3 and [Ru(η 4 ‐tetracyclone)(CO) 2 ] 2 were prepared from Ru 3 (CO) 12 and diphenylacetylene. Their rate of oxidation of PhCH 2 OH are, respectively, 1.6 and 4.2 times faster than their precursor Ru 3 (CO) 12 . Both complexes, as well as others, were also found in the oxidation reaction mixture: PhCH 2 OH+ Ph 2 C 2 + Ru 3 (CO) 12 which generates benzyl benzoate. Ru(η 4 ‐tetracyclone)(CO) 2 is most probably the true catalytic species in the catalytic oxidation of alcohols to esters.