The Cu(i) catalyzed Meerwein reaction in aqueous solutions proceeds via a radical mechanism. The effect of several ligands

Abstract

The effect of the ligands 2,5,8,11-tetramethyl-2,5,8,11-tetraaza-dodecane and fumarate on the mechanism and kinetics of the Cu(I) catalyzed Meerwein reaction was studied. The results point out that initially the Cu(I) ion binds to the aromatic ring with the diazo substituent. This reaction is followed by a redox process involving N2 loss and the formation of an aryl radical, R˙. The following kinetics depends on the nature of the ligand, its effect on the redox potential and the steric hindrance it induces on the central copper ion. Clearly the ligand 2,5,8,11-tetramethyl-2,5,8,11-tetraaza-dodecane does not form an optimal catalyst with Cu(I) while it does for the Ullmann reaction.

Xanthones with multiple roles against diabetes: their synthesis, structure‐activity relationship, and mechanism studies

“…The yield lied between 19% and 52%. As a matter of fact, nowadays, the mechanism of the Sandmeyer reaction is suggested as a single electron-transfer event (SET), where the diazonium halide is reduced to a diazonium radical and transformed to an aryl radical with a quick release of N 2 ; halo-ligand is then transferred to generate aryl halides (Burg et al, 2013). However, the preparation of aryl iodides and fluorides does not need the existence of copper(I) salts.…”

The interaction of carbon-centered radicals with copper(I) and copper(II) complexes*

“…Following the above work, where sufficiently stable organocopper(III) transients were generated and characterized from the spectroscopic and kinetic points of view, other reports have followed where species of this kind were invoked as intermediate in copper-catalyzed radical reactions [6,11,[56][57][58][59] and stable organocopper(III) complexes were isolated and fully characterized (next section).…”

First-row transition metal carbonates catalyze the electrochemical oxygen evolution reaction: iron is master of them all

“…[9][10][11][12] Recent studies have identified first-row transition metal carbonates as promising catalysts for electrochemical oxidation processes. [13][14][15][16][17][18][19][20][21][22] These metal carbonates, widely employed in industrial applications such as plastics, paper, paint, and rubber industries, have shown utility in various electrochemical catalytic reactions. [23][24][25][26] Metal carbonates are widely used in solid oxide fuel cells, batteries, and supercapacitors.…”

“…[27][28][29] Notably, the carbonate's role as σ-donor ligand stabilizes high oxidation states of metals like Mn III , Fe IV/III , Co V/IV/III , Ni III , and Cu IV/III , facilitating the stabilization of metal complexes' high oxidation states and partial radicalization of the carbonate ligand. 16,17,[30][31][32] In the high oxidation states of these complexes, the carbonate functions as an electron donor to the central metal cation, stabilizing the high oxidation states of metal complexes while also inducing partial radicalization of the carbonate ligand. 18,19 Additionally, metal complex intermediates in higher oxidation states boost electrochemical reactions.…”