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One‐step, two‐electron oxidation of cis ‐diaquabis(1,10‐phenanthroline)chromium(III) to cis ‐dioxobis(1,10‐phenanthroline)chromium(V) by periodate in aqueous acidic solutions
Author(s) -
Ali Ismat H.,
Sulfab Yousif
Publication year - 2011
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.20593
Subject(s) - chemistry , chromium , phenanthroline , reaction rate constant , periodate , aqueous solution , kinetics , inorganic chemistry , first order , medicinal chemistry , organic chemistry , physics , quantum mechanics , mathematics
The kinetics of oxidation of cis ‐[Cr III (phen) 2 (H 2 O) 2 ] 3+ (phen = 1,10‐phenanthro‐ line) by IO 4 − has been studied in aqueous acidic solutions. In the presence of a vast excess of [IO 4 − ], the reaction is first order in the chromium(III) complex concentration. The pseudo‐first‐order rate constant, k obs , showed a very small change with increasing [IO 4 − ]. The dependence of k obs on [IO 4 − ] is consistent with Eq. (i). iThe pseudo‐first‐order rate constant, k obs , increased with increasing pH, indicating that the hydroxo form of the chromium(III) complex is the reactive species. An inner‐sphere mechanism has been proposed for the oxidation process. The thermodynamic activation parameters of the processes involved are also reported. © 2011 Wiley Periodicals, Inc. Int J Chem Kinet 43: 563–568, 2011