New mono and dinuclear arene ruthenium chloro complexes containing ester substituents

The dinuclear arene ruthenium complexes [RuCl₂{C₆H₅(CH₂)₃OCO-<i>p</i>-C₆H₄-OC₈H₁₇}]₂ (<b>1</b>) and [RuCl₂{<i>p</i>-C₆H₄(CH₂COOCH₂CH₃)₂}]₂ (<b>2</b>) have been obtained by dehydrogenation of the corresponding cyclohexadiene derivative with ruthenium chloride hydrate. The single-crystal X-ray structure analysis of <b>2</b> shows the arene ligands to be involved in slipped-parallel π–π stacking interactions with neighbouring molecules, thus forming infinite chains along the b-axis. The dinuclear complexes <b>1</b> and <b>2</b> react with two equivalents of triphenylphosphine (PPh₃) to give in excellent yield the corresponding mononuclear phosphine complexes [RuCl₂{C₆H₅(CH₂)₃OCO-<i>p</i>-C₆H₄-OC₈H₁₇}(PPh₃)] (<b>3</b>) and [RuCl₂{<i>p</i>-C₆H₄(CH₂COOCH₂CH₃)₂}(PPh₃)] (<b>4</b>), respectively. The single-crystal X-ray structure analysis of <b>4</b> reveals the formation of a dimer through two C–HCl interactions in the solid state.