ORDERING OF RUTHENIUM CLUSTER CARBONYLS IN MESOPOROUS SILICA

The anionic ruthenium cluster carbonylates [Ru6C(CO)(16)](2-) or [H2Ru 10(CO)(25)](2-) interspersed with bis(triphenylphosphino)iminium count erions (PPN+) are incorporated from solution into the pores of MCM-41 mesoporous silica (3 nanometers in diameter), where they form tightly packed arrays. These arrays were shown by high-resolution transmission electron microscopy, Fourier transform optical diffraction, and compu ter simulations to be well ordered both along and perpendicular to the axis of the cylindrical pores. In their denuded state produced by gen tle thermolysis, the cluster carbonylates yield nanoparticles of ruthe nium that are less well ordered than their assimilated precursors but show good activity as hydrogenation catalysts for hexene and cycloocte ne. In both their as-prepared and denuded states, these encapsulated c lusters are likely to exhibit interesting electronic and other propert ies.