Synthesis and characterization of new M(II) carbonyl complexes (M = Fe or Ru) including an η1-N-maleimidato ligand. Reactivity studies with biological thiols

• Preparation and characterization of (η5-Cp*)Fe(CO)2(η1-maleimidato) and (η5-Cp)Ru(CO)2(η1-maleimidato) (X-ray structure).
• Reactivity of the metallocarbonyl maleimide derivatives toward cysteine derivatives (cysteine ethyl ester, GSH, HSA).
• kinetic studies of the reaction with GSH and HSA.
• quantum-chemical calculations and QTAIM analysis of (η5-Cp*)Fe(CO)2(η1-maleimidato) and (η5-Cp)Ru(CO)2(η1-maleimidato).
• FT–IR analysis of metallocarbonyl bioconjugates.

Herein we report the preparation and characterization of the iron and ruthenium organometallic maleimides (η5-Cp*)Fe(CO)2(η1-maleimidato) (Cp* = pentamethyl cyclopentadienyl) and (η5-Cp)Ru(CO)2(η1-maleimidato). The molecular structure of the ruthenium complex was confirmed by X-ray diffraction study. The reactivity of the metallocarbonyl maleimide derivatives toward biologically meaningful thiols, namely cysteine ethyl ester hydrochloride, glutathione (GSH) and human serum albumin (HSA) was investigated. To get better insight into the reaction mechanism, kinetic studies of the reaction with GSH and HSA were performed as well as quantum-chemical calculations and QTAIM analysis. We found out that the reactivity of the organometallic maleimides towards thiols depended on: 1) the metal present in the structure, 2) the nature of the capping aromatic ligand due to differences in electron donating capabilities and steric demands and 3) additional interactions like hydrogen bonding in (η5-Cp*)Fe(CO)2(η1-maleimidato) and carbonyl … carbonyl interactions in (η5-Cp)Ru(CO)2(η1-maleimidato).

Study of the reactivity of the new iron and ruthenium metallocarbonyl maleimide derivatives toward cysteine thiols (cysteine ethyl ester, GSH, HSA).Figure optionsDownload as PowerPoint slide