Stoichiometric sensitivity and structural diversity in click-active copper(I) N,S-heterocyclic carbene complexes

Abstract

A series of novel Cu(I) N,S-heterocyclic carbene (NSHC) complexes [Cu(μ-Br)(NSHC)]2, [Cu(μ-X)(NSHC)]4 (X = Br or I), [(NSHC)2Cu(μ-Br)2Cu(NSHC)], and [(NSHC) 2CuBr] have been isolated from in situ generated CuOtBu and N-substituted benzothiazolium halides and characterized by X-ray crystallography. Five structural motifs were observed, viz. MxL y where x:y = 2:2, 4:4, 2:3, 1:2 and 2:4, with Cu⋯Cu separation traversing over a wide range of 2.5626(7) to 3.4725(7) Å distances. A preliminary investigation of the catalytic activity of these compounds indicated that the unusual mononuclear complex 6 [(NSHC) 2CuBr] is an active catalyst for the Huisgen 1,3-dipolar cycloaddition of azide and alkynes while complexes 1-5 and 7 were marginally less active. © The Royal Society of Chemistry 2014.