Synthesis and reactivity of trinuclear osmium and dinuclear and trinuclear ruthenium compounds derived from hydroxyalkynes

Abstract

3-Hydroxy-3-methylbut-1-yne (HCCCMe₂OH) reacts with [Ru₃(CO)₁₂] to give [Ru₃H(CO)₉(CCCMe₂OH)] in very low yield as already described, but we can now report that the main products are isomeric compounds with empirical formula [Ru₂(CO)₆(alkyne)₂], which contain ruthenacyclopentadiene groups, and substituted benzenes formed by oligomerisation of three alkyne molecules. Much better yields of [Os₃H(CO)₉(C₂CMe₂OH)] are obtained in a similar way with no evidence for alkyne trimerisation or complex dimer formation. The complex [Os₃H₂(CO)₁₀] reacts at room temperature with HC₂CMe₂OH to give [Os₃(CO)₁₀(HC₂CMe₂OH)] and [Os₃H(Co)₁₀(CHCHCMe₂OH)]. The dynamic n.m.r. behaviour of the first of these and the thermal decarbonylations of both are described. The ¹H n.m.r. spectra of cationic clusters formed by hydroxide-ion loss in acidic solution are reported and the involvement of such cations in substitution and dehydration reactions of the η³ ligands.