Abstract
The kinetics of Fe(III) complexation by lipophilic 3-hydroxy-2-methyl-l(γ-stearoamidopropyl)-4-pyridinone (HMSP) were studied when [Fe(III)] > [HMSP] in MeOH/H2O mixed solvent and [Fe(III)] < [HMSP] in MeOH, respectively. When Fe(III) was in excess, the observed rate constants depend on [Fe(III)]2 tot and on the reciprocal of [H+] and decrease with increasing pressure. ΔV ‡ values are around +8.0 cm3 mol–1. A mechanism consisting of the complexations of the hydrolyzed monomer Fe(H2O)5OH2+ and dimer species Fe2(H2O)7 (μ-OH)2OH3+ by HMSP is proposed. This mechanism is supported by the solvent effect and the work of other researchers. When HMSP is in excess, Fe(HMSP)3 is formed and three kinetic steps on different time-scales are observed. An "intermolecular chelate ring-closure" mechanism is proposed, differing from the "intramolecular chelate ring-closure" complexation reported for the formation of ferrioxamine B.
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Received: 14 February 1997 / Accepted: 1 September 1997
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Shi, Y., Eyring, E., van Eldik, R. et al. Kinetics and mechanisms of Fe(III) complexation by lipophilic 3-hydroxy-2-methyl-1(γ-stearoamidopropyl)-4-pyridinone (HMSP). JBIC 2, 728–743 (1997). https://doi.org/10.1007/s007750050189
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DOI: https://doi.org/10.1007/s007750050189