Reactions of the pentanuclear mixed-metal cluster compound [Ru4RhC(CO)12(η5-C5Me5)]. Synthesis, characterisation and crystal structure of the pentanuclear derivative [Ru4RhC(CO)11H(η5-C5Me5)I]

Abstract

Treatment of the pentanuclear cluster [Ru₄RhC(CO)₁₂(η⁵-C₅Me₅)]1 with an excess of [NEt₄][BH₄] yielded the monoanion [Ru₄RhC(CO)₁₁H(η⁵-C₅Me₅)]^– which has been isolated as its [NEt₄]⁺ salt 2. Reaction of the monoanion with iodine solution gave the novel derivative [Ru₄RhC(CO)₁₁H(η⁵-C₅Me₅)I]3. Compound 3 crystallises in the monoclinic space group P2₁/n with a= 15.243(3), b= 18.683(3), c= 10.425(2)Å, β= 90.0(2)°. The five metal atoms adopt a wingtip-bridged butterfly arrangement with the rhodium forming one of the ‘hinge’ atoms [Ru–Ru 2.816(1)–2.899(1), Ru–Rh 2.816(1)–2.826(1)Å]. The parent cluster [Ru₄RhC(CO)₁₂(η⁵-C₅Me₅)]1 reacted at room temperature with the neutral ligands P(OMe)₃ and PPh₃ to yield compounds [Ru₄RhC(CO)₁₀{P(OMe)₃}₂(η⁵-C₅Me₅)]4(three isomers) and [Ru₄RhC(CO)₁₀(PPh₃)₂(η⁵-C₅Me₅)]5. Compound 1reacts with [N(PPh₃)₂]Cl to yield the adduct [Ru₄RhC(CO)₁₂(η⁵-C₅Me₅)Cl]^– which on protonation produces [Ru₄RhC(CO)₁₂H(η⁵-C₅Me₅)Cl]6.