The kinetic activation volumes for the binding of chloride to iron(III), studied by means of a high pressure laser temperature jump apparatus

1976 ◽  
Vol 54 (11) ◽  
pp. 1820-1826 ◽  
Author(s):  
Brian B. Hasinoff

The volumes of activation for the kinetics of the reaction of Cl− with Fe3+ and FeOH2+ have been determined by a laser temperature jump relaxation method at pressures up to 2.76 kbar. The results indicate that the two species, FeOH2+ and Fe3+, react with Cl− by different mechanisms. The activation volume for the binding of Cl− to FeOH2+ is positive (7.8 ± 1.0 cm3 mol−1), which is consistent with a dissociative interchange mechanism. The activation volume for the binding of Cl−1 to Fe3+ is negative (–4.5 ± 1.1 cm3 mol−1), which is consistent with an associative interchange mechanism.

1979 ◽  
Vol 57 (1) ◽  
pp. 77-82 ◽  
Author(s):  
Brian B. Hasinoff

The kinetics of the binding of Br− to Fe(III) were studied as a function of [H+] and [Br−] on a high pressure laser temperature jump apparatus up to 2.76 kbar. At constant [H+] the pseudo first order rate constant for formation of FeBr2+ showed little dependence on pressure or on [Br−] over the range 0.02 to 1.9 M. The results were interpreted by a mechanism in which Fe3+ and FeOH2+ react with Br− to form ion pairs prior to formation of their inner sphere complexes. The kinetic activation volume for the conversion of the Fe3+, Br− ion pair to FeBr2+ appears to be quite negative, consistent with an associative interchange (Ia) mechanism.


1974 ◽  
Vol 52 (6) ◽  
pp. 910-914 ◽  
Author(s):  
Brian B. Hasinoff

The relaxation kinetics of the reaction of iodide with cobalamin (vitamin B12) were studied on a high pressure laser temperature jump apparatus in aqueous solution at 25° and ionic strength 0.2 M. Analysis of the pressure dependence of the formation and dissociation rate constants gave their respective volumes of activation to be: ΔVf* = 5.50 ± 0.8 cm3 mol−1 and ΔVd* = 11.5 ± 1.6 cm3 mol−1 The positive activation volume for formation of the complex, ΔVf*, after appropriate correction for the volume change due to formation of an outer sphere complex, is consistent with a dissociative type mechanism in which the metal ion – water bond is stretched in the activated complex.


Biochemistry ◽  
1997 ◽  
Vol 36 (30) ◽  
pp. 9200-9210 ◽  
Author(s):  
Peggy A. Thompson ◽  
William A. Eaton ◽  
James Hofrichter

1974 ◽  
Vol 2 (4) ◽  
pp. 385-389 ◽  
Author(s):  
Douglas H. Turner ◽  
Raymond Yuan ◽  
George W. Flynn ◽  
Norman Sutin

1981 ◽  
Vol 36 (12) ◽  
pp. 1371-1377 ◽  
Author(s):  
M. Buback ◽  
H. Lendle

AbstractThe decomposition of tert. butylperoxypivalate dissolved in n-heptane has been measured ir-spectroscopically in optical high-pressure cells up to 2000 bar at temperatures between 65 °C and 105 °C. The reaction follows a first order rate law with an activation energy Ea = 122.3 ±3.0 kJ · mol-1 and an activation volume ⊿V≠ = 1.6 ± 1.0 cm3 mol-1 .


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