Back to basics: identification of reaction intermediates in the mechanism of a classic ligand substitution reaction on Vaska's complex

RSC Advances ◽  
2016 ◽  
Vol 6 (4) ◽  
pp. 3386-3392 ◽  
Author(s):  
Clara J. Durango-García ◽  
Said Jalife ◽  
José Luis Cabellos ◽  
Saul H. Martínez ◽  
J. Oscar C. Jimenez-Halla ◽  
...  
Keyword(s):  
Computational Methods ◽  
Substitution Reaction ◽  
Ligand Substitution ◽  
Reaction Intermediates ◽  
Ligand Substitution Reaction ◽  
Vaska's Complex

The mechanism of methylation of Vaska's complextrans-[ClIr(CO)(PPh3)2] by trimethylgallium was studied and the identification of the spectroscopically detected intermediates was achieved with the aid of computational methods.

scholarly journals Kinetics and mechanism of formation of the complex [Ru(CN)5INH]3− through the ligand substitution reaction between the aquapentacyanoruthenate(II) anion and isoniazid

2019 ◽  
Vol 44 (3) ◽  
pp. 244-256
Author(s):  
Rupal Yadav ◽  
Radhey Mohan Naik
Keyword(s):  
Ionic Strength ◽  
Substitution Reaction ◽  
Ligand Substitution ◽  
Yellow Colour ◽  
First Order ◽  
Charge Transfer Transitions ◽  
Colour Product ◽  
Pseudo First Order ◽  
Experimental Findings ◽  
Ligand Substitution Reaction

The formation kinetics of the complex, [Ru(CN)5INH]3−, formed through the ligand substitution reaction between isoniazid (INH) and aquapentacyanoruthenate(II) ([Ru(CN)5H2O]3−), have been investigated, under pseudo first-order conditions, as a function of concentrations of [INH] and [Ru(CN)5H2O]3−, ionic strength and temperature at pH = 4.0 ± 0.02 in 0.2 M NaClO4 spectrophotometrically at 502 nm ( λmax of intense yellow colour product [Ru(CN)5INH]3−) corresponding to metal-to-ligand charge-transfer transitions, in aqueous medium. The pseudo first-order condition was maintained by taking at least 10% excess of [INH] over [Ru(CN)5H2O]3−. The stoichiometry of the reaction product was found to be 1:1 which was further supported and characterized using elemental analysis, infrared, nuclear magnetic resonance and mass spectrometric techniques. Thermodynamic and kinetic parameters have also been computed, using the Eyring equation, and the values of ΔH≠, Ea, ΔG≠ and ΔS≠ were found to be 47.3 kJ mol−1, 49.8 kJ mol−1, −8.62 kJ mol−1 and 187.6 J K−1mol−1, respectively. The reaction was found to obey first-order kinetics with respect to [INH]. It exhibited a negative salt effect on the rate upon variation of ionic strength of the medium. A tentative mechanistic scheme was proposed on the basis of experimental findings.

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