The easy-to-prepare dimeric bis (μ-iodo) bis ((−)-sparteine) dicopper (I) complex is shown to be a versatile catalyst for N-arylation of number of NH–heterocycles with structurally divergent aryl halides including activated aryl chloride substrates under mild conditions. The DFT studies not only provide structural insights into square-pyramidal Cu (III) intermediate complexes derived from (−)-sparteine, but also highlight the important role of sterically ...