Genre
- Journal Article
The kinetics of nucleophilic substitution by cyanide ion at the bis-(2,3,5,6-tetrakis (2-pyridyl)pyrazine)iron(II) cation, [Fe(tppz)(2)](2+) have been measured, and the crystal structure of the product [Fe(tppz)-(CN)(3)](-) anion is reported. The kinetics of oxidation of bath [Fe(tppz)(2)](2+) and [Fe(tppz)(CN)(3)](-) by the peroxodisulfate anion have been studied. While the mechanism for the latter reaction follows a typical second-order-rate law, with activation enthalpy and entropy of 62+/-1 kJ mol(-1) and -82 +/- 3 J K-1 mol(-1), respectively, the oxidation of the [Fe(tppz)(2)](2+) cation obeys a remarkable overall first-order-rate law, that is zero-order in metal complex. The mechanism is interpreted in terms of rate-determining thermal fissure of peroxodisulfate into two sulfate radicals, with subsequent radical attack on the tppz ligand of the complex.
Univ Prince Edward Isl, Dept Chem, Charlottetown, PE C1A 4P3, Canada.; Haines, RI, Univ Prince Edward Isl, Dept Chem, 550 Univ Ave, Charlottetown, PE C1A 4P3, Canada.
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GORDON BREACH SCI PUBL LTD
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Source type: Electronic(1)
Language
- English
Subjects
- peroxodisulfate oxidation
- OSMIUM(II)
- SPECTROELECTROCHEMICAL PROPERTIES
- zero-order kinetics
- COMPLEXES
- 2,3,5,6-TETRAKIS(2-PYRIDYL)PYRAZINE
- WATER
- Chemistry, Inorganic & Nuclear
- tppz
- PEROXYDISULFATE
- cyanide substitution
- PEROXODISULFATE
- Ligands
- iron(II)
- ANION
- AQUEOUS-MEDIA