Catalysis of the deprotonation of β-diketones during formation of the 1:1 metal complexes
Blanco, Carlos A. Hynes, Michael J.
Blanco, Carlos A.
Hynes, Michael J.
Publication Date
1992-08-01
Type
journal article
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Citation
Blanco, Carlos A. Hynes, Michael J. (1992). Catalysis of the deprotonation of β-diketones during formation of the 1:1 metal complexes. Canadian Journal of Chemistry 70 (8), 2285-2289
Abstract
Catalytic effects on the deprotonation rate constants of beta-diketones were observed during kinetic studies of the formation reactions of the 1:1 complexes of these ligands. When vanadium(IV), chromium(III), iron(III), cobalt(II), nickel(II), copper(II), and uranium(VI) react with pentane-2,4-dione, heptane-3,5-dione, 1,1,1-trifluoropentane-2,4-dione, 4,4,4-trifluoro-1-(2-thienyl)-butane-1,3-dione, 1-phenylbutane-1,3-dione, and 2-acetylcyclohexanone a significant catalytic effect on the rate of ionization of the keto tautomer of the ligand was observed. A considerable enhancement of the rate of ionization of the enol tautomers of these ligands was observed during the complex formation reactions with Cu2+. A mechanism is proposed that accounts for these catalytic effects. In the case of Cu2+ the increased rate of proton removal from the ligands may be rationalized in terms of the relatively large reduction potential of this metal ion.
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Publisher
Canadian Science Publishing