Formula: C6H5NO2In 2021 ,《Mechanistic investigation of the aerobic oxidation of 2-pyridylacetate coordinated to a Ru(II) polypyridyl complex》 was published in Dalton Transactions. The article was written by Sousa, Sinval F.; Ertem, Mehmed Z.; Faustino, Leandro A.; Machado, Antonio Eduardo. H.; Concepcion, Javier J.; Maia, Pedro I. S.; Patrocinio, Antonio Otavio T.. The article contains the following contents:
A new ruthenium polypyridyl complex, [Ru(bpy)2(acpy)]+ (acpy = 2-pyridylacetate, bpy = 2,2′-bipyridine), was synthesized and fully characterized. Distinct from the previously reported analog, [Ru(bpy)2(pic)]+ (pic = 2-pyridylcarboxylate), the new complex is unstable under aerobic conditions and undergoes oxidation to yield the corresponding α-keto-2-pyridyl-acetate (acpyoxi) coordinated to the RuII center. The reaction is one of the few examples of C-H activation at mild conditions using O2 as the primary oxidant and can provide mechanistic insights with important implications for catalysis. Theor. and exptl. investigations of this aerobic oxidative transformation indicate that it takes place in two steps, first producing the α-hydroxo-2-pyridyl-acetate analog and then the final product. The observed rate constant for the first oxidation was in the order of 10-2 h-1. The reaction is hindered in the presence of coordinating solvents indicating the role of the metal center in the process. Theor. calculations at the M06-L level of theory were performed for multiple reaction pathways in order to gain insights into the most probable mechanism. Authors results indicate that O2 binding to [Ru(bpy)2(acpy)]+ is favored by the relative instability of the six-ring chelate formed by the acpy ligand and the resulting RuIII-OO ̇- superoxo is stabilized by the carboxylate group in the coordination sphere. C-H activation by this species involves high activation free energies (ΔG‡ = 41.1 kcal mol-1), thus the formation of a diruthenium μ-peroxo intermediate, [(RuIII(bpy)2(O-acpy))2O2]2+ via interaction of a second [Ru(bpy)2(acpy)]+ was examined as an alternative pathway. The dimer yields two RuIV:O centers with a low ΔG‡ of 2.3 kcal mol-1. The resulting RuIV:O species can activate C-H bonds in acpy (ΔG‡ = 23.1 kcal mol-1) to produce the coordinated α-hydroxo-2-pyridylacetate. Further oxidation of this intermediate leads to the α-keto-2-pyridyl-acetate product. The findings provide new insights into the mechanism of C-H activation catalyzed by transition-metal complexes using O2 as the sole oxygen source. In the experimental materials used by the author, we found Picolinic acid(cas: 98-98-6Formula: C6H5NO2)
Picolinic acid(cas: 98-98-6) is used as a chelate for alkaline earth metals. Used to prepare picolinato ligated transition metal complexes. In synthetic organic chemistry, has been used as a substrate in the Mitsunobu reaction and in the Hammick reaction.Formula: C6H5NO2