New copper(I) phosphane complexes of dihydridobis(3-nitro-1,2,4-triazolyl)borate ligand showing cytotoxic activity

New copper(I) complexes of the type [H2B(tzNO2)2]Cu[PR3]2 (1–5), [H2B (tzNO2)2]Cu[dppe] (6) and [H2B(tzNO2)2]Cu[PR3] (7, 8) have been synthesized from the reaction of CuCl, potassium dihydrobis(3-nitro-1,2,4-triazol-1-yl)borate, K[H2B (tzNO2)2], and mono- or bidentate tertiary phosphanes. The complexes obtained have been characterized by elemental analyses and FT-IR in the solid state, and by NMR (1H and 31P{1H}) spectroscopy in solution. Selected complexes 1, 3 and 5 have also been tested against a panel of several human tumor cell lines in order to evaluate their cytotoxic activity. Complexes 1 and 5 showed IC50 values appreciably lower than those exhibited by cisplatin, the most used metal-based antitumor drug. It is worth noting that all three tested Cu(I) complexes appear to be particularly effective against A549 carcinoma cells that are resistant to cisplatin treatment