The
reactions of potassium salts of the dithiocarbamates L {where L = pyrazolyldithiocarbamate (L1), 3,5-dimethylpyrazolyldithiocarbamate (L2), or indazolyldithiocarbamate
(L3)} with the gold precursors
[AuCl(PPh3)], [Au2Cl2(dppe)],
[Au2Cl2(dppp)], or [Au2Cl2(dpph)] lead to the new gold(I) complexes [AuL(PPh3)] (1–3), [Au2L2(dppe)] (4–6), [(Au2L2)(dppp)]
(7–9), and [Au2(L)2(dpph)] (10–12) {where dppe = 1,2-bis(diphenylphosphino)ethane, dppp =
1,3-bis(diphenylphosphino)propane, and dpph = 1,6-bis(diphenylphosphino)hexane}.
These gold compounds were characterized by a combination of NMR and
infrared spectroscopy, microanalysis, and mass spectrometry; and in
selected cases by single-crystal X-ray crystallography. Compounds 4–6, which have dppe ligands, are unstable
in solution for prolonged periods, with 4 readily transforming
to the Au18 cluster [Au18S8(dppe)6]Cl2 (4a) in dichloromethane. Compounds 1–3 and 7–12 are all active against human cervical epithelioid carcinoma (HeLa)
cells, but the most active compounds are 10 and 11, with IC50 values of 0.51 μM and 0.14
μM, respectively. Compounds 10 and 11 are more selective toward HeLa cells than they are toward normal
cells, with selectivities of 25.0 and 70.5, respectively. Further
tests, utilizing the 60-cell-line Developmental Therapeutics Program
at the National Cancer Institute (U.S.A.), showed 10 and 11 to be active against nine other types of cancers.
