The kinetics and thermodynamics of a novel efficient mixed water–1,4-dioxan solvent for the effective complexation of a neutral ruthenium complex with carbon monoxide at atmospheric pressure |
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Authors: | Ram S Shukla Vivek K Srivastava Munir D Khokhar Raksh V Jasra |
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Institution: | Discipline of Inorganic Materials and Catalysis, Central Salt and Marine Chemicals Research Institute (CSMCRI), G. B. Marg, Bhavnagar 364 002, Gujarat, India |
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Abstract: | Kinetic and thermodynamic investigations were performed for a mixed aqueous-organic, 1:1 (v/v) water–1,4-dioxane medium, which was found to be an efficient solvent for the interaction of a neutral dichlorotris(triphenylphosphine) ruthenium(II), RuCl2(PPh3)3 complex with carbon monoxide at atmospheric pressure. During the interaction, RuCl2(PPh3)3 dissociates to a neutral complex dichlorobis(triphenylphosphine) ruthenium(II), RuCl2(PPh3)2, by losing a coordinated PPh3 ligand and RuCl2(PPh3)2 coordinates with CO to form an in situ carbonyl complex RuCl2(CO)(PPh3)2. The in situ formed carbonyl complex RuCl2(CO)(PPh3)2 was thoroughly characterized by equilibrium, spectrophotometric, IR, and electrochemical techniques. Under equilibrium conditions, the rate and dissociation constants for the dissociation of PPh3 from RuCl2(PPh3)3 were found to be favorable for the formation of the carbonyl complex RuCl2(CO)(PPh3)2. The rates of complexation for the formation of RuCl2(CO)(PPh3)2 were found to follow an overall second-order kinetics being first order in terms of the concentrations of both carbon monoxide and RuCl2(PPh3)2. The determined activation parameters corresponding to the rate constant (ΔH# = 35.9 ± 2.5 kJ mol?1 and ΔS# = ?122 ± 6 J K?1 mol?1) and thermodynamic parameters corresponding to the formation constant (ΔH° = ?33.5 ± 4.5 kJ mol?1, ΔS° = ?25 ± 8 J K?1 mol?1, and ΔG° = ?25.7 ± 2.0 kJ mol?1) were found to be highly favorable for the formation of the complex RuCl2(CO)(PPh3)2. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 40: 359–369, 2008 |
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