Modulation of catalytic activity by ligand oxides in the sulfoxidation of phenylmercaptoacetic acids by oxo(salen)chromium(V) complexes
| Autor: | S. Sugirtha Devi, A. Ramdass, Perumal Subramaniam, S. Anbarasan |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
010405 organic chemistry
Chemistry Ligand Reactive intermediate Substituent 010402 general chemistry Photochemistry 01 natural sciences Medicinal chemistry 0104 chemical sciences Adduct Inorganic Chemistry chemistry.chemical_compound Catalytic cycle Pyridine Materials Chemistry Polar effect Physical and Theoretical Chemistry Triphenylphosphine oxide |
| Zdroj: | Polyhedron. 119:14-22 |
| ISSN: | 0277-5387 |
| Popis: | Mechanism of sulfoxidation of eleven para-substituted phenyl mercaptoacetic acids (PMAAs) by three oxo(salen)chromium(V) + PF 6 − complexes in the presence of different ligand oxides (LOs) such as triphenylphosphine oxide, pyridine N-oxide and 4-picoline N-oxide have been studied spectrophotometrically in 100% acetonitrile medium. Spectral and kinetic profiles establish the formation of adduct, O Cr(V)(salen) + -LO as the reactive intermediate in the catalytic cycle. The rate of sulfoxidation is found to be enhanced significantly by the addition of LOs and introduction of substituent in PMAA and salen complex. Both electron releasing and electron withdrawing substituents in the substrate and oxidant facilitate the rate of sulfoxidation. Correlation with Hammett constants yields a non-linear concave upward curve. Based on the experimental results and substituent effects two different mechanisms, a direct oxygen atom transfer (DOT) for PMAAs with electron withdrawing substituents and a single electron transfer for PMAAs with electron donating substituents have been postulated. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Full Text from ScienceDirect