Kinetic and mechanistic studies of the interaction of 2-mercapto pyridine with dichloro[1-alkyl-2-(arylazo)imidazole]palladium(II) complexes

Abstract

Nucleophilic substitution of Pd(RaaiR¢)Cl 2 [(RaaiR¢ = 1-alkyl-2-(arylazo)imidazole, p-R-C 6 H 4 -N=N-C 3 H 2 NN-1-R¢; where R = H(a)/ Me(b)/ Cl(c) and R¢ = Et(1)/Bz(2)] with 2-Mercaptopyridine (2-SH-Py) in acetonitrile (MeCN) at 298 K, to form [Pd 2 (2-S-Py) 4 ], has been studied spectrophotometrically under pseudo-first-order conditions and the analyses support the nucleophilic association path. The reaction follows the rate law, Rate = {k 0 + k [2-SH-Py] 0 2 }[Pd(RaaiR¢)Cl 2 ]: first order in Pd(RaaiR¢)Cl 2 and second order in 2-SH-Py. The rate of the reaction follows the order: 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) and HCl suppresses the rate (Rate µ 1/[Cl ) ] 0 & µ1/[HCl] 0 ). The reactions have been studied at different temperatures (293-308 K) and activation parameters (D z H o and D z S o ) of the reactions were calculated from the Eyring plot and support the proposed mechanism.

Synthesis, Spectral, Thermal and Biological Studies of Some Metal Complexes Derived from Heterocyclic Mono Azo Dye Ligand 2'[(2'-Hydroxy-4-methyl phenyl)azo]imidazole

“…These bands are located at (578 and 562) cm -1 and (480 and 432) cm -1 due to ν(M-O) and ν(M-N) respectively [24,39]. IR spectral data lead to suggest that the azo dye ligand (HMePAI) behaves as ionic tridentate chelating agent and coordination with metal ion by using sites are the nitrogen atom of the heterocyclic imidazole ring (N3), nitrogen atom of azo group nearest to a phenyl ring (N3) and a phenolic oxygen to forming two five membered chelating agent.…”

Kinetic and mechanistic studies on the Pd–Cl cleavage of dichloro‐ [1‐alkyl‐2‐(naphthylazo)imidazole]palladium(II) complexes by 2,2′‐bipyridine

“…A bidentate neutral N,N′‐chelating ligand is very useful for the preparation of Pd(II) complexes with cis ‐MCl 2 pattern, which is a model system to allow for exploration of the mechanism of the antitumor activity of cis platin. The kinetics and mechanism of the substitution reactions involving Pd(II) complexes of 1‐alkyl‐2‐(phenylazo)imidazoles ( i ) with adenine 17, cytosine 18, 2‐mercapto‐pyridine 19, 2‐amino‐pyrimidine 20, picolinic acid 21, and 8‐hydroxy quinoline 22 was reported. We are intending to incorporate higher steric crowding around the target metal center by using different ligands with azoimine‐chelating mode (–NNCN–), which will open a new avenue for exploring the mechanistic aspects of the nucleophilic interaction with the metal center under different local environments.…”

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

“…An alternative move forwards is to carry out reactions with structurally analogous Pd(II) complexes and extend this information to Pt(II) chemistry. The kinetics and mechanism of the substitution reactions involving Pd(II) complexes of 1-alkyl-2-(phenylazo)imidazoles (Scheme 1, i) with adenine [13], cytosine [14], 2-mercapto-pyridine [15], 2-amino-pyrimidine [16], picolinic acid [17] and 8-hydroxy quinoline [18] have been reported. We intend to incorporate higher steric crowding around the target metal centre by using different ligands with azoimine chelating mode (-N=N-C=N-), which will open a new avenue to explore the mechanistic aspects of nucleophilic interaction with the metal centre under different local environments.…”