Solid-gas hydrogenation of hex-3-yne and 1,4-cyclohexadiene in the presence of Ru-3(CO)(9)(mu-H)(mu-PPH2), Ru-3(CO)(10)(mu-H)(mu-PPh2), Ru-3(CO)(7)(mu-PPh2)(2)(C6H4) and Ru-4(CO)(11)(mu(4)-PPh)(C6H4) deposited on pyrex glass, silica and alumina

The title complexes were tested in the hydrogenation of hex-3-yne and of 1, 3- and 1,4-cyclohexadiene (CHD) under solid-gas conditions. The clusters we re deposited on three "standard" supports, that is, pyrex glass, alumina, a nd silica. All the clusters, particularly (mu -H)Ru-3(CO)(10)(PPh2), show h ydrogenation activity. However, they are not particularly selective toward the formation of monoenes; "disproportionation" of 1,3- and 1,4-CHD to hydr ogenated products and benzene also occurs. The hydrogenation activity of th e clusters is dependent on their nature, the type of substrate, and the cha racteristics of the supporting material; silica and pyrex glass are usually more active than alumina. Attempts at detecting the formation of organomet allic intermediates or by-products (through IR spectroscopy) were made. HRT EM was used to check for eventual decomposition on some supports.