The mixed-metal carbonyl cluster anion [Ru3Ir(CO)13]–: synthesis, molecular structure, fluxionality, reactivity†

Abstract

The new cluster anion [Ru₃Ir(CO)₁₃]^–1 was synthesized in high yield from [Ru₃(CO)₁₂] and [Ir(CO)₄^–. The single-crystal X-ray structure analysis of the bis(triphenylphosphoranylidene)ammonium salt revealed the presence of two isomers, [Ru₃Ir(CO)₁₁(µ-CO)₂]^–1a and Ru₃Ir(CO)₉(µ-CO)₄]^–1b in the same crystal. Both 1a and 1b present a tetrahedral Ru₃Ir framework, differing only by the number of bridging carbonyl ligands. Variable-temperature ¹³C NMR spectroscopic studies of 1 revealed the fluxionality of the carbonyl ligands and the interconversion of both isomers in solution. Protonation of 1 gave the neutral cluster [HRu₃Ir(CO)₁₃] 2, whereas reaction of 1 with molecular hydrogen yielded the anion [H₂Ru₃Ir(CO)₁₂]^–3. Either hydrogenation of 2 or protonation of 3 gave [H₃Ru₃Ir(CO)₁₂] 4. The tetrahedral structure of the hydrido derivatives was confirmed by a single-crystal X-ray structure analysis of the bis(triphenylphosphoranylidene)ammonium salt of 3.