SOLID-GAS REACTIONS OF METAL-CARBONYL CLUSTERS - HYDROGENATION OF 1,4-CYCLOHEXADIENE AND HEX-3-YNE IN THE PRESENCE OF H4RU4(CO)(12), RU-3(CO)(12) OR O)(MU(3)-CO)(MU(3)-PARALLEL-TO-C2PH2)(ETA-C5H5)(2)

The clusters H4Ru4(CO)(12) (1), Ru-3(CO)(12) (2) and Ru-3(CO)(3)(mu-CO )(mu(3)-CO) (mu(3)-parallel to-C2Ph2)(eta C5H5)(2) (3), which are homo geneous hydrogenation catalysts for alkynes and cyclic dienes, have be en investigated in solid-gas hydrogenation reactions. The clusters wer e deposited on porous glass discs in a new reaction vessel and reacted with the vapours of 1,4-cyclohexadiene or hex-3-yne and dihydrogen, g iving monoenes selectively. The apparatus is easy to use and allows th e collection and analysis of the gaseous phase with time; limitations are discussed, The reactions are catalytic, with low turnover numbers (TON). Sublimation of the clusters and of reaction products onto the g lass walls of the apparatus, formation and recondensation of metal fra gments and/or of metallacyclic derivatives were observed during the ex periments, The behaviour of the clusters under solid-gas conditions wa s found to be similar to that under homogeneous conditions. Comparable organometallic intermediates or byproducts have been isolated suggest ing that the same reaction pathways occur. This work shows for the fir st time that electronically saturated clusters in the solid state can react with mixtures of gases under relatively mild conditions.