Synthesis, structure and cytotoxicity studies of diisopropylammonium and triethylammonium salts of triphenylphosphinegold(I) sulfanylcarboxylates

Compounds of the type [HQ][Au(PPh3)(xspa)] and [HP][Au(PPh3)(xspa)] {HQ = diisopropylammonium; HP = triethylammonium; H2xspa = 3-aryl-2-sulfanylpropenoic acids [x: p = 3-phenyl-, f = 3-(2-furyl)-, t = 3-(2-thienyl)-, -o-py = 3-(2-pyridyl)-, Clp = 3-(2-chlorophenyl)-, -o-mp = 3-(2-methoxyphenyl)-, -p-mp = 3-(4-methoxyphenyl)-, -o-hp = 3-(2-hydroxyphenyl)-, -p-hp = 3-(4-hydroxyphenyl)-, diBr-o-hp = 3-(3,5-dibromo-2-hydroxyphenyl]} were synthesized and characterized by IR and NMR (1H, 13C and 31P) spectroscopy and by FAB mass spectrometry. The structures of [HQ][Au(PPh3)(Clpspa)] and [HQ][Au(PPh3)(-o-mpspa)] show that the crystal contains hydrogen-bonded diisopropylammonium cations and [Au(PPh3)(xspa)]− anions. The anions in the two compounds have different structures, with the carboxylate group either coordinated or not coordinated to the gold atom, respectively. The in vitro antitumour activities against the HeLa-229, A2780 and A2780cis cell lines were determined for all complexes. The diisopropylammonium derivatives were generally found to be more active, in particular against the A2780cis cell line, and showed a high ability to circumvent the cellular resistance to cisplatin.