The first comparative study of C, S, Se and P donor ligands-supported copper(I) complexes for C–N and C–Si bond formation reactions are described. The syntheses and characterization of eight mononuclear copper(I) chalcogenone complexes, two polynuclear copper(I) chalcogenone complexes and one tetranuclear copper(I) phosphine complex are reported. All these new complexes were characterized by CHN analysis, FT-IR, UV-vis, multinuclear NMR and single crystal X-ray diffraction techniques. The single crystal X-ray structures of these complexes depict the existence of a wide range of coordination environments for the copper(I) center. This is the first comparative study of metal–phosphine, metal–NHC and metal–imidazolin-2-chalcogenones in C–N and C–Si bond formation reactions. Among all the catalysts, mononuclear copper(I) thione, mononuclear copper(I) N-heterocyclic carbene and tetranuclear copper(I) phosphine are exceedingly active towards the synthesis of 1,2,3-triazoles as well as for the cross-dehydrogenative coupling of alkynes with silanes. The cross-dehydrogenative coupling of terminal alkynes with silanes represents the first report of a catalytic process mediated by metal–imidazolin-2-chalcogenones.