PdII–PdII bonding interaction in dinuclear PdII complex with non-macrocyclic (O&N) chelates: Characterization, kinetics and DFT study

• Published in: Polyhedron 2015-03, Vol.89, p.101-109
• Main Authors: Mitra, Ishani, Ghosh, Goutam Kr, Mukherjee, Subhajit, Reddy B., Venkata P., Linert, Wolfgang, Kubel, Frank, Rocquefelte, Xavier, Moi, Sankar Ch
• Format: Article
• Language: English
• Subjects: 2-Aminomethylpyridine; Condensed Matter; Cyclobutane-1,1-dicarboxylic acid; DFT study; Materials Science; PdII–PdII bonding interaction; Physics; Third order kinetics
• ISSN: 0277-5387; 0277-5387
• DOI: 10.1016/j.poly.2015.01.012

A unique PdII complex with metal–metal (d8–d8) bonding interaction, [Pd(pic)(cbdca)]2·H2O (pic=2-aminomethylpyridine and cbdca2−=cyclobutane-1,1-dicarboxylate) has been synthesised and characterized by spectroscopic methods. Density Functional Theory (DFT) study shows PdII–PdII bond distance of 3.18Å in the complex which is close to the observed distance of 3.1790(1)Å found from X-ray crystal structure. [Display omitted] A unique PdII complex with metal–metal (d8–d8) bonding interaction, [Pd(pic)(cbdca)]2·H2O 4 (where, pic=2-aminomethylpyridine and cbdca2−=cyclobutane-1,1-dicarboxylate) has been synthesised and characterized by X-ray structure, FT-IR, ESI Mass, Raman and NMR spectroscopy. Density Functional Theory (DFT) study shows PdII–PdII bond distance of 3.18Å in complex 4 which is close to the observed distance of 3.1790(1)Å found from X-ray crystal structure. Powder X-ray structure of [Pd(pic)Cl2] 1 has been solved and polymeric chain structure is found without any supporting ligand. At pH 5.5, complex [Pd(pic)(OH2)2](ClO4)22, the hydrolyzed product of 1 exists as dimeric complex [Pd(pic)(OH)]2(ClO4)23. Third order kinetics is followed for the reaction of cbdca with the di-μ-hydroxo bridged dimer 3. The substitution process is a ligand-dependent second order reaction, found to take place in two consecutive steps in accordance with the rate law kobs=k1[cbdca]2. The reaction follows an associative mechanistic path and the activation parameters (ΔH‡ and ΔS‡) for both the steps were evaluated using Eyring equation.