ETA(5)-PENTAMETHYLCYCLOPENTADIENYLRUTHENIUM(II) COMPLEXES CONTAINING ETA(6)-CO-ORDINATED DIPEPTIDES WITH AROMATIC SIDE-CHAINS

The eta(6)-co-ordinated amino acid complexes [RU(eta(5)-C(5)Me(5))(eta (6)-HaaOH)][CF3SO3] [HaaOH = L-HPheOH (phenylalanine) or L-HTrpOH (try ptophan)] were prepared by reaction of [Ru(eta(5)-C(5)Me(5))(MeCN)(3)] [CF3SO3] with the relevant amino acid in tetrahydrofuran. Dipeptide co mplexes of the type )-C(3)Me(5))}(2)(mu-eta(6):eta(6)-pep)][CF3SO3](2) [pep = HPhe-PheOH, cyclo(-Phe-Phe-), HTrp-TrpOH, or cyclo(-Trp-Trp-)] may be obtained under analogous conditions. Ultraviolet irradiation o f ta(5)-C(5)Me(5))}(2){cyclo(-Phe-Phe-)}][CF3SO3](2) leads to photoche mical release of cyclo(-Phe-Phe-) in quantitative yield. The feasibili ty of peptide synthesis from individual amino acid complexes was demon strated by the preparation of [Ru(eta(5)-C(5)Me(5)){eta(6)-cyclo(-Phe- Phe-)}]Cl from [Ru(eta(5)-C(5)Me(5))(eta(6)-L-HPhe-OMe)]Cl by the carb odiimide method. A crystal structure analysis was carried out a(5)-C(5 )Me(5))}(2){cyclo(-Phe-Phe-)}][CF3SO3](2).