Phenylalanine--a biogenic ligand with flexible η6- and η6:κ1-coordination at ruthenium(II) centres

• Published in: Dalton transactions : an international journal of inorganic chemistry 2013-06, Vol.42 (24), p.8692-8703
• Main Authors: Reiner, Thomas, Jantke, Dominik, Miao, Xiao-He, Marziale, Alexander N, Kiefer, Florian J, Eppinger, Jörg
• Format: Article
• Language: English
• Subjects: Chemistry - methods; Chemistry, Pharmaceutical - methods; Chlorides - chemistry; Crystallography, X-Ray - methods; Cyclohexenes - chemistry; Dimethyl Sulfoxide - chemistry; Drug Design; Esters; Ligands; Magnetic Resonance Spectroscopy - methods; Metals - chemistry; Molecular Conformation; Phenylalanine - analogs & derivatives; Phenylalanine - chemistry; Ruthenium - chemistry; Solvents - chemistry
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/c3dt50589h

The reaction of (S)-2,5-dihydrophenylalanine 1 with ruthenium(III) chloride yields the μ-chloro-bridged dimeric η(6)-phenylalanine ethyl ester complex 3, which can be converted into the monomeric analogue, η(6):κ(1)-phenylalanine ethyl ester complex 12, under basic conditions. Studies were carried out to determine the stability and reactivity of complexes bearing η(6)- and η(6):κ(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 η(6):κ(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 η(6):κ(1)-phenylalanine complex 17 and an N-κ(1)-phenylalanine complex 13 resulting from the reaction of 3 with an excess of pyridine were confirmed by X-ray crystallography.