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The Kinetics of the Anation Reaction of Aquopentaamminerhodium(III) lon by Oxalate in Aqueous Acidic Solution
Author(s) -
van Eldik R.
Publication year - 1975
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.19754160111
Subject(s) - oxalate , chemistry , aqueous solution , ionic strength , ion , kinetics , reaction rate constant , inorganic chemistry , medicinal chemistry , nuclear chemistry , organic chemistry , physics , quantum mechanics
The anation reaction of aquopentaamminerhodium(III) by oxalate has been studied in the temperature range 51–69°C and acidity range 0 ≤ pH ≤ 4.5 for oxalate concentrations up to 0.25 M and at ionic strength 1.0 M. The kinetic results provide evidence for the formation of an ion‐pair between the complex ion and HC 2 O 4 − (Q 1 ) and C 2 O 4 2− (Q 2 ), where Q 1 = 2.3 M −1 and Q 2 = 8.1 M −1 at 60°C, but no evidence for an ion‐pair with H 2 C 2 O 4 exists. The values of the rate constants at 60°C for anation by H 2 C 2 O 4 , HC 2 O 4 −and C 2 O 4 2− are k 0 = 1.5 · 10 −4 M −1 sec −1 , k 1 = 1.4 · 10 −4 sec −1 and k 2 = 1.2 · 10 −4 sec −1 . The corresponding values for ΔH≠ and ΔS≠ are reported and the results discussed with reference to analogous reactions of Rh(III) and Co(III).