Ru₂(CO)₄(OOCR)₂(PPh₃)₂ sawhorse-type complexes containing μ₂-η²-carboxylato ligands derived from biologically active acids

The thermal reaction of Ru₃(CO)₁₂ with the biologically active acids acetyl salicylic acid (Aspirin), α-methyl-4-(isobutyl)phenylacetic acid (Ibuprofen) and 3α,7α,12α-trihydroxy-5β-cholanic acid (cholic acid) in refluxing tetrahydrofuran, followed by addition of triphenylphosphine, gives the dinuclear complexes Ru₂ (CO) ₄(OOCR)₂(PPh₃)₂ (<b>1</b>: R = C₆H₄-2-OCOMe, <b>2</b>: R = CHMe-C₆H₄-4-Buⁱ, <b>3</b>: C₂₃H₃₉O₃). The single-crystal structural analysis of <b>1</b> and <b>2</b> reveals a dinuclear Ru₂(CO)₄ sawhorse structure, the diruthenium backbone being bridged by the carboxylato ligands, while the two phosphine ligands occupy the axial positions at the ruthenium atoms. However, chiral carbon atoms in the carboxylic acid undergo racemisation during the thermal reaction.