Reactions of the hexanuclear mixed-metal cluster [Ru5RhC(CO)14(η5-C5Me5)] and the synthesis, characterisation and structural analysis of the pentanuclear derivative [Ru4RhC(CO)12(η5-C5Me5)]

Abstract

Treatment of the hexanuclear cluster [Ru₅RhC(CO)₁₄(η⁵-C₅Me₅)]1 with 80 atmospheres of CO under 80 °C resulted in a series of decapping reactions yielding the complexes, [Ru₃(CO)₁₂], [Ru₅C(CO)₁₅] and a new green compound [Ru₄RhC(CO)₁₂(η⁵-C₅Me₅)]2. Cluster 2 crystallises in the monoclinic space group P2₁/n with a= 19.180(3), b= 13.940(3) and c= 10.728(2)Å, β= 97.157(2)°. The five metal atoms adopt a square-based pyramidal metal framework [Ru–Ru 2.776(1)–2.873(1), Ru–Rh 2.798(1)–2.881 (1)Å]. The octahedral cluster [Ru₅RhC(CO)₁₄(η⁵-C₅Me₅)]1 reacted at room temperature with a methanolic base to yield the methoxide adduct [Ru₅RhC(CO)₁₃(CO₂Me)(η⁵-C₅Me₅)]^–3 which on acidification immediately regenerated the parent compound. On prolonged stirring, cluster 1 reacted irreversibly with the methanolic base to form the salt [N(PPh₃)₂]₂[Ru₅RhC(CO)₁₃(η⁵-C₅Me₅)]4.