Preparation, Reactivity and Peptide Labelling Properties of (η6-Arene)ruthenium(II) Complexes with Pendant Carboxylate Groups
✍ Scribed by Ralf Stodt; Susan Gencaslan; Iris M. Müller; William S. Sheldrick
- Publisher
- John Wiley and Sons
- Year
- 2003
- Tongue
- English
- Weight
- 235 KB
- Volume
- 2003
- Category
- Article
- ISSN
- 1434-1948
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✦ Synopsis
Abstract
(η^6^‐Arene)ruthenium(II) complexes of the type [{[η^6^‐C~6~H~5~(CH~2~)~n~COOH]Ru(µ‐Cl)Cl}~2~] (2a, n = 1; 3, n = 3) with tethered carboxylate groups can be obtained by dehydrogenation of the appropriate cyclohexadiene with RuCl~3~·3H~2~O. Formation of a κO‐coordinated chelate in weakly acidic solution is observed by means of a ^1^H NMR titration for both {η^6^‐C~6~H~5~(CH~2~)~3~COOH}Ru(aq)~2~ (3a′) and {η^6^‐C~6~H~5~(CH~2~)~3~COOH}Ru(phen)(aq)~2~ (5′). Sandwich complexes of the type {η^6^‐C~6~H~5~(CH~2~)~3~COOH}Ru(η^6^‐amino acid)~2~ [amino acid = AcpheOH (6), ActyrOEt (7), ActrpOH (8)] can be prepared by treating {η^6^‐C~6~H~5~(CH~2~)~3~COOH}Ru(acetone)~3~~2~ with the appropriate aromatic bioligand in CF~3~COOH (6/8) or CH~2~Cl~2~ (7). Chemospecific η^6^‐labelling of the C‐terminal indole function is observed for the peptide HphetrpOH in the analogous complex 9. Quantitative formation of 8 can also be achieved in aqueous solution in the presence of a 3:1 excess of the {η^6^‐C~6~H~5~(CH~2~)~3~COOH}Ru^II^ fragment. This can also be employed for the N‐terminal labelling of amino acids and peptides in its sandwich complex (η^6^‐C~6~Me~6~)Ru{η^6^‐C~6~H~5~(CH~2~)~3~COOH}~2~ (10). Coupling reactions by the carbodiimide method with EDC afford water‐stable complexes of the type (η^6^‐C~6~Me~6~)Ru{η^6^‐C~6~H~5~(CH~2~)~3~C(O)R}~2~ [R = trpOMe (11), pheOMe (12), glyglyOEt (13)] in good yields. X‐ray structures of (η^6^‐C~6~H~5~CH~2~COOC~2~H~5~)RuCl(phen) (4b′) and 10 are reported. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)