Treatment of bis(pyrazolyl)borate ligand supported [(CF3)(2)Bp]Cu(NCMe) with 1,2,3-trisubstituted cyclopropenes produced thermally stable copper(I) eta(2) -cyclopropene complexes amenable to detailed solution and solid-state analysis. The [(CF3)(2)Bp]Cu(NCMe) also catalyzed [2 + 1]-cycloaddition chemistry of terminal and internal alkynes with ethyl diazoacetate affording cyclopropenes, including those used as ligands in this work. The tris(pyrazolyl)borate [(CF3)(2)Tp]Cu(NCMe) is a competent catalyst for this process as well. The treatment of [(CF3)(2)Tp]Cu with ethyl 2,3-diethylcycloprop-2-enecarboxylate substrate gave an O-bonded rather than a eta(2) -cyclopropene copper complex.