Synthesis, characterization and biological activity of organotitanium substituted heteropolytungstates

Eight new compounds alpha- and beta-MxHy[(CpTi)(3)XW9O37]. nH(2)O (M = K+, x = 4, y = 3; M = NBu4+, x = 7, y = 0; X = Si, Ge) have been synthesized from vacant heteropolytungstate precursors alpha-, beta-[XW9O34](10-) (X = Si, Ge) and Cp2TiCl2. The products were characterized by elemental analysis, IR, UV-VIS spectroscopy, H-1 NMR, W-183 NMR spectroscopy and polarography. W-183 NMR spectra of the complexes support the stoichiometry of the new heteropolyanions and the probable retention of the A-XW9 units in water. The organotitanium substituted complexes showed promising activity in two human tumor cell lines in vitro.