Untitled

2005

Self Cite

Nucleophilic substitution of Pd(RaaiR¢)Cl 2 [RaaiR¢=1-alkyl-2-(arylazo)imidazole, p-RAC 6 H 4 AN@NAC 3 H 2 NN-1-R¢; where R= H(a)/Me(b)/Cl(c) and R¢ = Et(1)/Bz(2)] with adenine (A) in MeCN-water (1:1) at 298 K, to form [Pd(A) 2 ]Cl 2 , has been studied spectrophotometrically under pseudo-first-order conditions and the analyses support a nucleophilic association path. The reaction follows the rate law, rate = {a+k [A] 2 0 g[Pd(RaaiR¢)Cl 2 ]: first-order in Pd(RaaiR¢)Cl 2 and second-order in A. The rate increases as follows: Pd(RaaiEt)Cl 2 (1) < Pd(RaaiBz)Cl 2 (2) and Pd(MeaaiR¢)Cl 2 (b) < Pd(HaaiR¢)Cl 2 (a) < Pd(ClaaiR¢)Cl 2 (c). External addition of Cl ) (LiCl) suppresses the rate (rate µ 1/[Cl ) ]). The activation parameters, D z H 0 and D z S 0 of the reactions were calculated from the Eyring plot and support the proposed mechanism.

Section: Resultsmentioning

confidence: 83%

Section: Resultsmentioning

confidence: 99%

Interaction Between Pd(RaaiR′)Cl2 and Adenine: Reaction Dynamics and Mechanism [RaaiR′ = 1-alkyl-2-(arylazo)imidazole]

Saha

Ghosh

2005

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“…Adenine (Aldrich) was used as purchased. Acetonitrile was purified by a known procedure [29,30]. All kinetic and spectroscopic measurements were recorded on an Agilent 8453E UV-Visible Spectrometer.…”

Section: Methodsmentioning

confidence: 99%

Interaction of adenine with dichloro-[1-alkyl-2-(naphthylazo)-imidazole]palladium(II) complexes: kinetic and mechanistic studies

Ghosh

Mandal

2010

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Interaction of adenine (A) with dichloro-[1-alkyl-2-(a-naphthylazo)imidazole] palladium(II) [Pd-(a-NaiR)Cl 2 ], 1 and dichloro- 4b, 4c) was studied. The products were characterized by physico-chemical and spectroscopic methods. The reaction kinetics were second order overall, being first order in both the Pd(II) complex and adenine. The effect of adding chloride was consistent with rate-limiting dissociation of chloride from the complex. Thermodynamic parameters were determined from temperature variation experiments. The second-order rate constant k 2 corroborates with the experimental D à H°values, while the negative values of D à S°i ndicate that the reaction proceeds through an associative inner sphere mechanism.

“…It was then chromatographed following above mentioned procedure. Yield: 0.028 g, -2-(arylazo)imidazoles are N,N¢-chelating ligands having an azoimine group, )N=N)C=N), as the chelating unit [5][6][7][8][9][10][11]. In this work, six known 1-alkyl-2-(arylazo)imidazole complexes of palladium(II) were used, see Scheme 1.…”

Section: Product Isolation and Characterizationmentioning

confidence: 99%

“…They form Pd(N,N¢)Cl 2 complexes having the cis-PdCl 2 configuration [7]. We have been engaged for several years in the study of the reactions of pyridines [8], a-diimines [9], and picolinic acid [10] with Pd(N,N¢)Cl 2 . As a sequel to our earlier observations, in this work we now explore the reaction of picolinic acid (picH), a monoanionic-N, O donor, with Pd(N,N¢)Cl 2 .…”

Section: Introductionmentioning

confidence: 99%

Kinetics and Mechanism of the Reactions of Picolinic Acid with Dichloro-{1-alkyl-2-(arylazo)imidazole}palladium(II) Complexes

Saha

Sarkar

2006

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The reaction between Pd(N,N¢)Cl 2 [N,N¢ " 1-alkyl-2-(arylazo)imidazole (N,N¢) and picolinic acid (picH) have been studied spectrophotometrically at k=463 nm in MeCN at 298 K. The product is [Pd(pic) 2 ] which has been verified by the synthesis of the pure compound from Na 2 [PdCl 4 ] and picH. The kinetics of the nucleophilic substitution reaction have been studied under pseudo-first-order conditions. The reaction proceeds in a two-step-consecutive manner (A fi B fi C); each step follows first order kinetics with respect to each complex and picH where the rate equations are: Rate 1={k¢ 0 +k¢ 2 [picH] 0 } Â [Pd(N,N¢)Cl 2 ] and Rate 2={k¢¢ 0 +k¢¢ 2 [picH] 0 }[Pd(N,O)(monodentate N,N¢)Cl 2 ] such that the first step second order rate constant (k¢ 2 ) is greater than the second step second order rate constant (k¢¢ 2 ). External addition of Cl ) (as LiCl) suppresses the rate. Increase in p-acidity of the N,N¢ ligand, increases the rate. The reaction has been studied at different temperatures and the activation parameters (D à H°and D à S°) were calculated from the Eyring plot.