Synthesis, Structure and Antitumor Activity of Dibutyltin Oxide Complexes with 5-Fluorouracil Derivatives. Crystal Structure of [(5-Fluorouracil)-1-CH(2)CH(2)COOSn(n-Bu) (2)](4)O(2)

Dibutyltin (IV) oxide complex reacts with the fluorouracil compounds 5-fluorouracil-1-propanonic or 5-fluorouracil-1-acetic acid (Fu) to give the complexes [(5-Fu)-1-(CH(2))(n)COOSn(n-Bu)(2)](4)O(2) (I, n=2; II, n=1) which were characterized by IR and (1)H-NMR. The crystal structure of complex I shows that the molecular is a dimer, in which two [(5-Fu)-1-CH(2)CH(2)COOSn(n-Bu)(2)](2)O units are linked by a bridging oxygen atom, and the tin atoms adopt distorted trigonal bipyramids via two carbons from a dibutyl moiety and three oxygen atoms from 5-Fu and bridging oxygen. These complexes have potential anti-tumour activity: in vitro tests showed that complexes I and II exhibit high cytotoxicity against OVCAR-3 and PC-14.