New dinuclear arene ruthenium complexes with <i>P</i>,<i>S</i>- or <i>P</i>,<i>O</i>-chelating ligands

Two equivalents of 2-diphenylphosphinobenzoic acid react with 1,2-ethanedithiol and 1,8-diaminonaphthalene under peptidic coupling conditions to give the new ligands 1,2-bis-S-[2′-(diphenylphosphino)benzoyl]dithioethane (dppte) (<b>1</b>) and 1,2-bis-<i>N</i>-[2′-(diphenylphosphino)benzoyl]diaminonaphthalene (dppan) (<b>2</b>), respectively. <b>1</b> and <b>2</b> have been characterised by mass spectrometry, elemental analysis, NMR, IR spectroscopy, and by single-crystal X-ray structure analysis. <b>2</b> is easily oxidised by air to give the monophosphine oxide derivatives (<b>3</b>). Single-crystal X-ray structure analysis of <b>3</b> shows an intramolecular hydrogen bond between an amido and the phosphoryl oxygen atom. Compounds <b>1</b> and 2 react with [RuCl2(η⁶-p-cymene)]2 to give the dinuclear complexes [RuCl(η⁶-<i>p</i>-cymene)(dppte)RuCl(η⁶-<i>p</i>-cymene)]2+ (<b>4</b>) and [RuCl(η⁶-<i>p</i>-cymene)(dppan)RuCl(η⁶-<i>p</i>-cymene)]2+ (<b>5</b>). As determined by single-crystal X-ray structure analysis, 4 and 5 adopt different coordination modes to the ruthenium atoms. In <b>4</b> the symmetric dppte ligand is <i>P,S</i> coordinated to the ruthenium atom, whereas in <b>5</b> the dppan ligand prefers a <i>P,O</i> coordination mode.