Catalytic alcohol oxidation using cationic Schiff base manganeseIII complexes with flexible diamino bridge. (1st January 2021)

• Record Type: Journal Article
• Authors: Neshat, Abdollah; Osanlou, Farzane; Kakavand, Meysam; Mastrorilli, Piero; Schingaro, Emanuela; Mesto, Ernesto; Todisco, Stefano
• Is Part Of: Polyhedron. Volume 193(2021)
• Publication Date: 2021-01-01
• Subjects: Alcohol oxidation -- Catalysis -- Metal-oxo -- Schiff base; Chemistry, Inorganic -- Periodicals; Chimie inorganique -- Périodiques; Organometaalverbindingen; Anorganische chemie; 546.05
• DOI: 10.1016/j.poly.2020.114873
• Languages: English
• ISSNs: 0277-5387

Abstract

Graphical abstract: Manganese (III) catalysts supported with salen ligands of flexible bridging group were prepared and applied as catalysts for the oxidation of a variety of primary and secondary alcohols. Regardless of the type of substituents, these complexes are efficient catalysts for oxidation reactions in the presence of imidazole and TBHP oxidant. Highlights: A series of metal complexes with Salen ligands were synthesized. All metal complexes show catalytic activity in alcohol oxidation reactions. Mechanistic studies reveals a metal-oxo intermediate for the alcohol oxidation reactions. Abstract: Four Schiff base manganese(III) complexes with derivatives of [( R, R )-N, N'-bis(salicy1idene)-1, 2-cyclohexanediaminato)] including substituents on salicylaldehyde such as 3-methoxy, 3, 5-di- tert -butyl and 3, 5-chloro were synthesized and characterized using a combination of IR, UV–Vis, and HR ESI-MS techniques. The catalytic activity of these complexes was tested in the oxidation of 1-phenylethanol to acetophenone, revealing very good performances for all of the four manganese complexes. The catalytic reactions were carried out in the presence of tert -butyl hydroperoxide (TBHP) as oxidant and imidazole as co-catalyst. Complex Mn-4, bearing electron withdrawing [( R, R )-N, N'-bis(3, 5-di-chloro-salicylidene)-1, 2-cyclohexanediaminato)] ligand was found to be the most stable of the tested Mn(III) complexes and was selected for the oxidation of several primary and secondary alcohols.