Abstract
The reaction of (S)-2,5-dihydrophenylalanine 1 with ruthenium(III) chloride yields the mu-chloro-bridged dimeric eta(6)-phenylalanine ethyl ester complex 3, which can be converted into the monomeric analogue, eta(6):kappa(1)-phenylalanine ethyl ester complex 12, under basic conditions. Studies were carried out to determine the stability and reactivity of complexes bearing eta(6)- and eta(6):kappa(1)-chelating phenylalanine ligands under various conditions. Reaction of 3 with ethylenediamine derivatives N-p-tosylethylenediamine or 1,4-di-N-p-tosylethylenediamine results in the formation of monomeric eta(6):kappa(1)-phenylalanine ethyl ester complexes 14 and 15, which could be saponified yielding complexes 16 and 17 without changing the inner coordination sphere of the metal centre. The structure of eta(6):kappa(1)-phenylalanine complex 17 and an N-kappa(1)-phenylalanine complex 13 resulting from the reaction of 3 with an excess of pyridine were confirmed by X-ray crystallography.