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