Dicopper Cu(I)Cu(I) and Cu(I)Cu(II) Complexes in Copper-Catalyzed Azide–Alkyne Cycloaddition

Abstract

A discrete, dicopper μ-alkynyl complex, [Cu(μ-η:η-C≡C(CH)CH)DPFN]NTf (DPFN = 2,7-bis(fluoro-di(2-pyridyl)methyl)-1,8-naphthyridine; NTf = N(SOCF)), reacts with p-tolylazide to yield a dicopper complex with a symmetrically bridging 1,2,3-triazolide, [Cu(μ-η:η-(1,4-bis(4-tolyl)-1,2,3-triazolide))DPFN]NTf. This transformation exhibits bimolecular reaction kinetics and represents a key step in a proposed, bimetallic mechanism for copper-catalyzed azide-alkyne cycloaddition (CuAAC). The μ-alkynyl and μ-triazolide complexes undergo reversible redox events (by cyclic voltammetry), suggesting that a cycloaddition pathway involving mixed-valence dicopper species might also be possible. Synthesis and characterization of the mixed-valence μ-alkynyl dicopper complex, [Cu(μ-η:η-C≡C(CH)CH)DPFN](NTf), revealed an electronic structure with an unexpected partially delocalized spin, as evidenced by electron paramagnetic resonance spectroscopy. Studies of the mixed-valence μ-alkynyl complex's reactivity suggest that a mixed-valence pathway is less likely than one involving intermediates with only copper(I).

Exploration of Antifungal Potential of Carbohydrate‐Tethered Triazoles as CYP450 Inhibitors

“…The most accepted mechanism of Huisgen 1,3-Dipolar cycloaddition ("Click Reaction") involved the two copper centered transition state. [16][17][18][19][20][21] The reaction initiated with the activation of alkyne with the aid of two copper atoms which facilitated the attack of negative centered nitrogen of sugar azide over the alkyne and trough the concerted cycloaddition the desired products were formed ( Figure 2).…”

Naphthyridine‐based iridium complexes: Structures and catalytic activity on alkylation of aryl ketones

“…Indeed, quite a number of 2 and/or 7-substituted 1,8-naphthyridine-based ligands have been investigated for their coordination and catalytic activity. [2][3][4][5][6][7][8][9][10] Besides acting as a donor in coordination, the nitrogen atom in naphthyridine is also able to act as a pendant group to serve as a base for promotion of the catalytic reactions. In a recent report, Bera et al found that complex [RuH(CO)(py-NP)(PPh3)2]Cl [py-NP = 2-pyridinyl-1,8-naphthyridine] is able to catalyze the oxidation of primary alcohols into the corresponding carboxylic acid via the dehydrogenation of alcohol followed by a hydroxide/water attack on the metalbound aldehyde.…”

Binuclear Copper(I) Borohydride Complex Containing Bridging Bis(diphenylphosphino) Methane Ligands: Polymorphic Structures of [(µ2-dppm)2Cu2(η2-BH4)2] Dichloromethane Solvate

“…Many examples The Cu(I)-dppm complexes are emerging class of polynuclear complexes, that are drawing considerable attention because of their photophysical properties [19][20][21][22] and prospective use as a catalyst [23][24][25] and a sensor for various organic bases [26] and anions [27]. Binuclear Cu(I) species possess an enhanced reactivity toward organic azides in copper-catalysed azide-alkyne cycloaddition compared to monomeric copper complexes [28][29][30][31][32][33][34][35]. Copper(I) tetrahydroborates with phosphine ligands featuring relative stability to air oxygen and moisture are used as selective reducing agents [36][37][38][39][40], catalysts of photosensitized isomerization of dienes [41][42][43] and hydrolytic dehydrogenation of ammonia borane [44].…”

“…Binuclear Cu(I) species possess an enhanced reactivity toward organic azides in copper-catalysed azide-alkyne cycloaddition compared to monomeric copper complexes [28][29][30][31][32][33][34][35]. Copper(I) tetrahydroborates with phosphine ligands featuring relative stability to air oxygen and moisture are used as selective reducing agents [36][37][38][39][40], catalysts of photosensitized isomerization of dienes [41][42][43] and hydrolytic dehydrogenation of ammonia borane [44].…”