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

摘要

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. MxLy 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) ? 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.