Collect. Czech. Chem. Commun. 2007, 72, 492-502

Zinc and Cobalt(II) Complexes of Tripodal Nitrogen Ligands of the Tris[2-substituted Imidazol-4(5)-yl]phosphane Type. Biomimetic Hydrolysis of an Activated Ester

Peter C. Kunz* and Wolfgang Kläui

Heinrich-Heine-Universität, Institut für Anorganische Chemie, Universitätsstr. 1, D-40225 Düsseldorf, Germany


Novel tris[2-substituted imidazol-4(5)-yl]phosphane (4-TIPR) ligands 2b (R = Ph) and 2c (R = tBu) were prepared as model ligands for the tris(histidine) motif found in many zinc enzymes. They readily form cobalt and zinc nitrato and chloro complexes in protic solvents. The steric requirements of the substituents R in 4(5)-position of the 4-TIPR ligands (R = iPr (2a), Ph (2b), tBu (2c)) is discussed on the basis of their UV/VIS spectra. Zinc complexes of 2a and 2c were studied due to their ability to promote the hydrolysis of the activated ester 4-nitrophenyl pyridine-2-carboxylate (pNpic).

Keywords: Bioinorganic chemistry; Enzyme models; N ligands; Tripodal ligands; Water solubility; Zinc; Cobalt; Phosphines; Imidazoles; UV spectroscopy.

References: 29 live references.