The rate of hydrolysis of the aromatic rings of Cp2TiX2 [X = CI 1, O2CCCl3 8 and
O2CCH2NH3Cl 13], in aqueous solutions, 10%DMSO and 100% DMSO have been studied by H1NMR spectroscopy. Rapid hydrolysis of both the carboxylate and cyclopentadienyl ligands in
Cp2TiX2[X = O2CCCl3,O2CCH2NH3Cl] occurs in DMSO to give biologically inactive species. The
rate of these reactions are concentration dependent as dilution of these samples with saline or
water to give the therapeutic conditions of 10%DMSO/90%H2O slows the hydrolysis chemistry. In
contrast, samples of Cp2TiX2 [X = CI 1, O2CCH2NH3Cl 13], dissolved in water give solutions
containing the presumed antitumour active species in which the halide or glycine ligands have
been hydrolysed but the Cp rings remain metal bound.