New arene ruthenium complexes with planar chirality

1,2,4-Trimethyl-cyclohexadiene reacts with RuCl3 nH2O in refluxing ethanol to afford quantitatively [RuCl2(1,2,4-C6H3Me3)] (1), the coordination of 1,2,4-trimethylbenzene to the ruthenium atom introducing planar chirality at the g-arene ligand. Th dinuclear complex 1 reacts with two equivalents of triphenylphosphine (PPh3) to give quantitatively, as a racemic mixture o enantiomers, [RuCl2(1,2,4-C6H3Me3)(PPh3)] (2), the structure of which has been determined by a single-crystal X-ray structur analysis of (rac)-2. Similarly, 1 reacts with two equivalents of the enantiopure phosphine (1S,2S,5R)-(+)-neomenthyldipheny phosphine (nmdpp) to afford in good yield [RuCl2(1,2,4-C6H3Me3)(nmdpp)] (3) as a mixture of diastereoisomers, from which th isomer 3a was isolated by crystallisation. A single-crystal X-ray structure analysis of 3a allowed the determination of the absolut configuration at the planar chiral g-arene moiety. Finally, complex 1 reacts with one equivalent of the diphosphine ligand 1,1 bis(diphenylphosphino)ferrocene (dppfc) to give the heteronuclear complex [RuCl2(1,2,4-C6H3Me3) (dppfc)RuCl2(1,2,4-C6H3Me3 (4). All complexes were fully characterised by elemental analysis, mass spectrometry, NMR and IR spectroscopies.