Kinetics of the mercury(II)-catalyzed substitution of coordinated cyanide ion in hexacyanoruthenate(II) by nitroso-R-salt

✍ Scribed by Radhey M. Naik; Abhinav Agarwal; Amit K. Verma; Shiv Bali S. Yadav; Basant Kumar

• Publisher: John Wiley and Sons
• Year: 2009
• Tongue: English
• Weight: 298 KB
• Volume: 41
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.20391

✦ Synopsis

Abstract

The kinetics and mechanism of Hg^2+^‐catalyzed substitution of cyanide ion in an octahedral hexacyanoruthenate(II) complex by nitroso‐R‐salt have been studied spectrophotometrically at 525 nm (λ~max~ of the purple‐red–colored complex). The reaction conditions were: temperature = 45.0 ± 0.1°C, pH = 7.00 ± 0.02, and ionic strength (I) = 0.1 M (KCl). The reaction exhibited a first‐order dependence on [nitroso‐R‐salt] and a variable order dependence on [Ru(CN)~6~^4−^]. The initial rates were obtained from slopes of absorbance versus time plots. The rate of reaction was found to initially increase linearly with [nitroso‐R‐salt], and finally decrease at [nitroso‐R‐salt] = 3.50 × 10^−4^ M. The effects of variation of pH, ionic strength, concentration of catalyst, and temperature on the reaction rate were also studied and explained in detail. The values of k~2~ and activation parameters for catalyzed reaction were found to be 7.68 × 10^−4^ s^−1^ and E~a~ = 49.56 ± 0.091 kJ mol^−1^, Δ__H__^≠^ = 46.91 ± 0.036 kJ mol^−1^, Δ__S__^≠^ = −234.13 ± 1.12 J K^−1^ mol^−1^, respectively. These activation parameters along with other experimental observations supported the solvent assisted interchange dissociative (I~d~) mechanism for the reaction. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 41: 215–226, 2009