Synthesis of mercury-linked ruthenium clusters: the X-ray structure of the new cluster dianion [{Ru6C(CO)16}2Hg]2– and the cluster [{Ru5C(CO)14(µ-Cl)}2Hg2Cl2]

Abstract

Reaction of the hexaruthenium dianion [Ru₆C(CO)₁₆]^2–1 as its [N(PPh₃)₂]⁺ salt in CH₂Cl₂ with an equimolar quantity of Hg(CF₃CO₂)₂ leads to an uncharacterised black polymer of probable formula [Ru₆C(CO)₁₆Hg]_n. However, treatment of 2 equivalents of 1 in CH₂Cl₂ with 1 equivalent of Hg(CF₃CO₂)₂ or 2 equivalents of HgCl₂ in the same solvent has yielded the new dodecaruthenium dianion [{Ru₆C(CO)₁₆}₂Hg]^2–2. This red dianion has been characterised as its [N(PPh₃)₂]⁺ salt by single-crystal X-ray diffraction analysis and shown to contain two octahedral Ru₆C units linked through a mercury atom. It is probably produced from the uncharacterised intermediate monoanion [Ru₆C(CO)₁₆(HgX)]^–3a(X = Cl or CF₃CO₂). In agreement with this suggestion, treatment of 1 with the compound Hg(CF₃)(CF₃CO₂) yields the monoanion [Ru₆C(CO)₁₆(HgCF₃)]^–3b which has been fully characterised on the basis of its spectroscopic data. We have also observed that the neutral pentaruthenium cluster [Ru₅C(CO)₁₅]4 reacts with HgCl₂ to produce the dark red decaruthenium species [{Ru₅C(CO)₁₄(µ-Cl)}₂Hg₂Cl₂]5. On the basis of single-crystal X-ray diffraction analysis this cluster has been shown to consist of two distorted bridged-butterfly Ru₅C(CO)₁₄(µ-Cl) units linked by a Hg₂(µ-Cl)₂ unit. In solution, it appears that the dimeric cluster 5 undergoes dissociation to a monomer believed to be [Ru₅C(CO)₁₄(µ-Cl)(HgCl)]6. The mass spectrum of cluster 5 is not totally consistent with this unit and in the fast atom bombardment mass spectrum, the ion corresponding to [Ru₅C(CO)₁₃(µ-Cl)(HgCl)]7 is observed.