Two diphosphane ligands -2,5-bis(2-(diphenylphosphino)-5-R)phenyl)-1,3,4-oxadiazole (L1, R = H, L2, R = OMe) and their binuclear complexes, L1Cu and L2Cu, were prepared and characterized. The molecular structures of L1Cu and L2Cu, as perchlorate salts, were established by X-ray crystallography, which showed them to be binuclear complexes with each Cu atom tetrahedrally coordinated by two P atoms and two N atoms. The ligands and their Cu(I) complexes catalyzed Sonogashira coupling reactions of iodobenzene with phenylacetylene in the presence of K 2 CO 3 under Pd-free conditions. Coupling reactions catalyzed by L1 or L2 with Cu(MeCN) 4 ClO 4 in situ exhibited better yields than those by the corresponding Cu(I) complexes L1Cu or L2Cu. Detailed studies showed L1 or L2 with Cu(MeCN) 4 ClO 4 to be suitable catalysts for the coupling reaction of terminal alkynes and aryl halides. The coupling reactions of aryl iodides with electron-withdrawing groups showed better results.