Synthesis and Cytotoxicity Studies of Silyl-Substituted Titanocene Dichloride Derivatives

Six new titanocene compounds have been isolated and characterized. These compounds were synthesized from their silyl-substituted fulvene or cyclopentadiene precursors using Super Hydride (LiBEt3H) or n-BuLi, followed by transmetalation with titanium tetrachloride, to yield the corresponding titanocene dichloride derivatives. These complexes are bis-[((phenyl)­dimethylsilane)­cyclopentadienyl] titanium­(IV) dichloride (3a), bis-[((4-methoxyphenyl)­dimethylsilane)­cyclopentadienyl] titanium­(IV) dichloride (3b), bis-[((4-N,N-dimethylmethanamine)­dimethylsilane)­cyclopentadienyl] titanium­(IV) dichloride (3c), bis-[((4-N,N-diethylmethanamine)­dimethylsilane)­cyclopentadienyl] titanium­(IV) dichloride (3d), bis-[((1-methyl-5-trimethylsilyl)­indol-3-yl)­methylcyclopentadienyl] titanium­(IV) dichloride (4e), and bis-[((1-methyl-3-diethylaminomethyl-5-trimethylsilyl)­indol-2-yl)­methylcyclopentadienyl] titanium­(IV) dichloride (4f). The two titanocenes 3a and 3b were crystallized and characterized by X-ray crystallography, while all six titanocenes were tested for their cytotoxicity through MTT-based in vitro tests on CAKI-1 cell lines in order to determine their IC50 values. Titanocenes were found to have IC50 values of 139 (±5), 106 (± 4), 127 (±4), 104 (±9), 90 (±6), and 15 (±2) μM.