Ligand dehydrogenation in ruthenium trinitrogen complexes: synthesis, structure and chirality of the cations [Ru(LH4)(L)]2+ [LH4=2,6-bis(pyrrolidin-2-yl)pyridine]

Reaction of 2,6-bis(pyrrolidin-2-yl)pyridine (LH4) with RuCl3·3H2O in refluxing methanol/water mixtures gives rise to the formation of the octahedral complexes [Ru(LH4)(L)]2+, in which one of the two trihapto ligands has been dehydrogenated as 2,6-bis(3,4-dihydro-2H-pyrrol-5-yl)pyridine (L), even if LH4 was present in excess. With the three stereoisomers of LH4, the complexes [Ru(R,S-LH4)(L)]2+ (meso), [Ru(R,R-LH4)(L)]2+ and [Ru(S,S-LH4)(L)]2+ have been isolated as the perchlorate salts and characterised by X-ray structure analysis and by CD spectra.