TY - JOUR
T1 - Spontaneous reactions and reduction by iodide of peroxynitrite and peroxynitrate
T2 - Mechanistic insight from activation parameters
AU - Goldstein, Sara
AU - Meyerstein, Dan
AU - Van Eldik, Rudi
AU - Czapski, Gidon
PY - 1997/9/18
Y1 - 1997/9/18
N2 - Thermal and pressure activation parameters are reported for the decomposition of peroxynitrate, isomerization of peroxynitrite, and their reduction by iodide in aqueous solutions. The spontaneous decomposition reactions are characterized by activation enthalpies of ca. 16 kcal/mol, activation entropies close to zero, and significantly positive activation volumes between 7 and 10 cm3/mol. These parameters suggest that the rearrangement of both peroxo species, leading to intermediates of increased partial molar volume, must include partial bond cleavage. The iodide-induced reduction reactions are characterized by significantly smaller activation enthalpies, negative activation entropies between -19 and -23 cal/(mol·K), and negative activation volumes between -6 and -11 cm3/mol. These parameters suggest that bond formation between the redox partners occurs before electron transfer and favors an inner-sphere mechanism. The results are discussed regarding mechanisms based on ambient kinetic data suggested in the literature.
AB - Thermal and pressure activation parameters are reported for the decomposition of peroxynitrate, isomerization of peroxynitrite, and their reduction by iodide in aqueous solutions. The spontaneous decomposition reactions are characterized by activation enthalpies of ca. 16 kcal/mol, activation entropies close to zero, and significantly positive activation volumes between 7 and 10 cm3/mol. These parameters suggest that the rearrangement of both peroxo species, leading to intermediates of increased partial molar volume, must include partial bond cleavage. The iodide-induced reduction reactions are characterized by significantly smaller activation enthalpies, negative activation entropies between -19 and -23 cal/(mol·K), and negative activation volumes between -6 and -11 cm3/mol. These parameters suggest that bond formation between the redox partners occurs before electron transfer and favors an inner-sphere mechanism. The results are discussed regarding mechanisms based on ambient kinetic data suggested in the literature.
UR - http://www.scopus.com/inward/record.url?scp=0031236423&partnerID=8YFLogxK
U2 - 10.1021/jp971506f
DO - 10.1021/jp971506f
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AN - SCOPUS:0031236423
SN - 1089-5639
VL - 101
SP - 7114
EP - 7118
JO - Journal of Physical Chemistry A
JF - Journal of Physical Chemistry A
IS - 38
ER -