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Updated: Apr 13, 2026

Preparation of a Corannulene-functionalized Hexahelicene by CopperI-catalyzed Alkyne-azide Cycloaddition of Nonplanar Polyaromatic Units
Published on: September 18, 2016
Dicopper Cu(I)Cu(I) and Cu(I)Cu(II) Complexes in Copper-Catalyzed Azide-Alkyne Cycloaddition
Micah S Ziegler1,2, K V Lakshmi3, T Don Tilley1,2
1Department of Chemistry, University of California , Berkeley, California 94720-1460, United States.
Abstract:
A discrete, dicopper μ-alkynyl complex, [Cu2(μ-η1:η1-C≡C(C6H4)CH3)DPFN]NTf2 (DPFN = 2,7-bis(fluoro-di(2-pyridyl)methyl)-1,8-naphthyridine; NTf2- = N(SO2CF3)2-), reacts with p-tolylazide to yield a dicopper complex with a symmetrically bridging 1,2,3-triazolide, [Cu2(μ-η1:η1-(1,4-bis(4-tolyl)-1,2,3-triazolide))DPFN]NTf2. 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, [Cu2(μ-η1:η1-C≡C(C6H4)CH3)DPFN](NTf2)2, 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).
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