Catalysis of redox isomerization of allylic alcohols by [RuClCp(mPTA)2](OSO2CF3)2 and [RuCp(mPTA)2(OH2-κO)](OSO2CF3)3·(H2O)(C4H10O)0.5. Unusual influence of the pH and interaction of phosphate with catalyst on the reaction rate

In aqueous solutions at 80 °C, [RuClCp(mPTA)2](OSO2CF3)2 (1) and [RuCp(mPTA)2(OH2-κO)](OSO2CF3)3·(H2O)(C4H10O)0.5 (3) (mPTA: N-methyl-PTA) were found effective catalysts of the redox isomerization of alk-1-en-3-ols to the corresponding ketones, characterized by initial turnover frequencies (TOF) of 162 h−1 (3) and 9.6 h−1 (1) in 1-octen-3-ol isomerization. A sharp maximum of the reaction rate as a function of pH was observed with 1 in phosphate buffer solutions. Kinetic and 31P NMR measurements revealed for the first time in aqueous organometallic catalysis that component(s) of phosphate buffer (most probably HPO42−) strongly interact(s) with the catalyst complexes and this interaction leads to a dramatic loss of the catalytic activity.

The title complexes catalyzed effectively the redox isomerization of alk-1-en-3-ols. A reaction rate maximum against pH, and strong interaction of [RuCl(Cp)(mPTA)2](OSO2CF3)2 (mPTA: N-methyl-PTA) with phosphate buffer was observed.Figure optionsDownload high-quality image (72 K)Download as PowerPoint slide