Gold nanoparticles supported on passivated silica: access to an efficient aerobic epoxidation catalyst and the intrinsic oxidation activity of gold.

Well-defined and perfectly dispersed [( identical withSiO)Au(I)] surface species supported on silica have been obtained via surface organometallic chemistry and transformed upon mild reduction (H(2), 300 degrees C) into small (1.8 +/- 0.6 nm) Au particles supported on silica passivated with SiMe(3) functionalities. Improved performance in liquid-phase aerobic epoxidation has been achieved, and the intrinsic activity of gold in oxidation is revealed.