The structural reformulation of [ Ru2Cl4(Me2SO)5]

Abstract

New i.r. and n.m.r. (¹H and ¹³C-{¹H}) studies establish that [Ru₂Cl₄(Me₂SO)₅], which forms on heating wet solutions of [RuCl₂(Me₂SO)₄], contains exclusively S-bonded terminal sulphoxide ligands and should be reformulated as a triple chloro-bridged diruthenium(II) complex, i.e.[(Me₂SO)₃RuCl₃RuCl(Me₂SO)₂]. The ¹³C resonances for O-bonded and S-bonded Me₂SO ligands are well separated. Analogous [Ru₂Cl₄L₅] complexes, with L = NCMe, pyridine, or 4-methylpyridine (4Me-py), are not formed due to the relative non-lability of [RuCl₂(NCMe)₄], etc. Both [RuCl₂(Me₂SO)₄]⁺ and mixed-valence [Ru₂Cl₄(Me₂SO)₅]⁺ can be generated electrochemically, though the former is thermally unstable in contrast to [RuCl₂(4Me-py)₄]⁺.