Alcohol Oxidation by Dioxygen and Aldehydes Catalysed by Square-Planar Cobalt(III) Complexes of Disubstituted Oxamides and Related Ligands

Abstract

The square-planar cobalt(III) complexes of o-phenylenebis(NЈ-methyloxamidate) (Me 2 opba) and related oxamate (Meopba) and bis(oxamate) (opba) ligands catalyse the selective oxidation, by dioxygen and pivalaldehyde, of a wide range of secondary alcohols to the corresponding ketones, in good yields and under mild conditions in acetonitrile at room temperature. Thus, the oxidation of the series of α-alkylbenzyl alcohols PhCH(OH)R (R = Me, Et, iPr, tBu) results in the exclusive formation of ketones as a product of C−H bond cleavage, and no C−C bond cleavage products are observed in any case. The modulation of catalytic activity by ligand substituents among this series of cobalt catalysts highlights the role of oxocobalt(IV) species as the putative inter-

Mononuclear nickel and copper complexes with indolecarboxamide ligands: Synthesis, properties and electrochemistry

“…Interestingly, the spectral features for species [11 ox ] + are in close similarity to that of square-planar Cu 3+ species of a set of macrocyclic ligands reported from our laboratory [24]. Moreover, the absorption spectrum of the Cu 3+ species of a tetra-anionic tetraamide ligands by Journaux and co-workers display similar features [55,56] that have been assigned as the transition from four low-lying fully occupied d orbitals to the upper empty d orbital for a Cu 3+ ion with a d 8 electronic configuration in a square-planar environment [51,52,55,56,63,64]. We speculate a similar electronic transition for the Cu 3+ species.…”

Epoxidation of Styrene with H2O2 Catalyzed by Alanine–Salicylaldehyde Schiff Base Chromium (III) Complexes Immobilized on Mesoporous Materials

“…Among the various transition metal complexes reported [9][10][11][12][13][14][15][16][17], the amino acid Schiff base complexes have been proven to be excellent catalysts for catalytic epoxidation [13,14]. However, such homogeneous complexes suffer from the drawbacks of poor catalyst recovery and product separation [18].…”

Study on Effect of Cuso4 and Mnso4 on the Reaction Rate of Substituted Alcohols by N-Bromophthalimide in Aqueous Acetic Acid Medium

“…The study completely discards the formation of complexes and rules out the involvement of cations catalytic in oxidation process. We employ a variety of metal catalysts containing Cu(I) [1,2] , Ni(II) [3,4] , Co(II) [5,6] , Pd(II) [7,8] and manganese oxide [9][10][11] recently developed and have been used for many decades. However, most of the metal catalysts are expensive and may lead to the environmental pollution with the overgrowing economic concerns.…”