Kinetic and mechanistic studies on the Pd–Cl cleavage of dichloro- [1-alkyl-2-(naphthylazo)imidazole]palladium(II) complexes by 2,2′-bipyridine
✍ Scribed by Pradip Kumar Ghosh; Harasit Kumar Mandal; Ambikesh Mahapatra
- Publisher
- John Wiley and Sons
- Year
- 2010
- Tongue
- English
- Weight
- 194 KB
- Volume
- 43
- Category
- Article
- ISSN
- 0538-8066
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✦ Synopsis
Abstract
The interaction of 2,2′‐bipyridine with dichloro‐[1‐alkyl‐2‐(α‐naphthylazo) imidazole]palladium(II) [Pd(α‐NaiR′)Cl~2~, 1] and dichloro‐[1‐alkyl‐2‐(β‐naphthylazo) imidazole] palladium(II) [Pd(β‐NaiR′)Cl~2~, 2] complexes {where alkyl R′ = Me (a), Et (b) or Bz (c)} in acetonitrile medium to yield [{1‐alkyl‐2‐(α‐naphthylazo) imidazole} (bipyridine)] palladium(II)diperchlorate (3a, 3b, 3c) and [{1‐alkyl‐2‐(β‐naphthylazo) imidazole}(bipyridine)] palladium(II) diperchlorate (4a, 4b, 4c) was studied. The products were characterized by microanalytical data and spectroscopic techniques (FT‐IR, UV–vis, and NMR). The nucleophilic substitution reaction shows a first‐order dependence of rate on each of the Pd(II) complex and 2,2′‐bipyridine. Addition of LiCl to the reaction decreases the rate of reaction and has proved the cleavage of Pd–Cl bond at the rate‐determining step. Thermodynamic parameters standard enthalpy of activation (Δ^‡^H°), and standard entropy of activation (Δ^‡^S°) were determined. The second‐order rate constant k~2~ corroborates with the experimental Δ^‡^H° values. The negative values of Δ^‡^S° indicate that the reaction proceeds through an associative inner sphere mechanism. © 2010 Wiley Periodicals, Inc. Int J Chem Kinet 43: 130–140, 2011