Substituent effects in dioxovanadium(V) schiff-base complexes: Tuning the outcomes of oxidation reactions. (1st September 2021)

• Record Type: Journal Article
• Authors: McCaffrey, Vanessa P.; Conover, Olivia Q.; Bernard, Michael A.; Yarranton, Jonathan T.; Lessnau, Nicholas R.; Hempfling, Jordan P.
• Is Part Of: Polyhedron. Volume 205(2021)
• Publication Date: 2021-09-01
• Subjects: Vanadium -- Schiff-base ligands -- Oxidation -- Oxidative cleavage -- Epoxidation; Chemistry, Inorganic -- Periodicals; Chimie inorganique -- Périodiques; Organometaalverbindingen; Anorganische chemie; 546.05
• DOI: 10.1016/j.poly.2021.115268
• Languages: English
• ISSNs: 0277-5387

Abstract

Graphical abstract: Dioxovanadium(V) salicylaldehyde semicarbazone complexes with electron donating or withdrawing substituents to investigate how changing the electronic properties of the ligand affected the oxidation of styrene. Abstract: Dioxovanadium(V) salicylaldehyde semicarbazone complexes with substituents on the ligand that span the range of electron donating (methoxy) to electron withdrawing (nitro) have been synthesized and characterized by NMR, IR, CV and EPR. The reactivity of these complexes toward the oxidation of styrene (as compared to the proteo complex and vanadyl acetylacetonate) has been studied in the presence of two different oxidants (hydrogen peroxide and tert -butyl hydrogen peroxide, TBHP). The complexes have been shown to exhibit different selectivity towards epoxidation versus oxidative cleavage based on the substitution of the ligand and the oxidant chosen. Epoxidation is favored with the methoxy substituted complex in the presence of hydrogen peroxide, while oxidative cleavage is the preferred reaction pathway for the nitro substituted complex with hydrogen peroxide. Conversions for these reaction are comparable to similar catalysts but with improved selectivity.