Solid-gas hydrogenation of hex-3-yne and 1,4-cyclohexadiene in the presence of Ru3(CO)9(μ-H)(μ-PPH2), Ru3(CO)10(μ-H)(μ-PPh2), Ru3(CO)7(μ-PPh2)2(C6H4) and Ru4(CO)11(μ4-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 were deposited on three "standard" supports, that is, pyrex glass, alumina, and silica. All the clusters, particularly (mu -H)Ru-3(CO)(10)(PPh2), show hydrogenation activity. However, they are not particularly selective toward the formation of monoenes; "disproportionation" of 1,3- and 1,4-CHD to hydrogenated products and benzene also occurs. The hydrogenation activity of the clusters is dependent on their nature, the type of substrate, and the characteristics of the supporting material; silica and pyrex glass are usually more active than alumina. Attempts at detecting the formation of organometallic intermediates or by-products (through IR spectroscopy) were made. HRTEM was used to check for eventual decomposition on some supports.