Preparation and anti-tumour activity of some arylbismuth(III) oxine complexes

Abstract

New arylbismuth(lll) oxinates, PhBi(MeOx)₂, (p-MeC₆H₄)Bi(Ox)₂, (p-MeC₆H₄)Bi(MeOx)₂, (p-ClC₆H4)Bi(Ox)₂, and (p-ClC₆H₄)Bi(MeOx)₂ (Ox− = quinolin-8-olate and MeOx−=2-methylquinolin-8-olate) have been prepared by reaction of the appropriate diarylbismuth chlorides with Na(Ox) or Na(MeOx) in the presence of 15-crown-5. An X-ray crystallographic study has shown PhBi(MeOx)₂ to be a five coordinate monomer with distorted square pyramidal stereochemistry. Chelating MeOx ligands have a cisoid arrangement in the square plane and the phenyl group is apical. The lattice is stabilised by significant π-π interactions between centrosymmetric molecules. A range of these complexes has been shown to have high in vitro biological activity (comparable with or better than cisplatin) against L1210 leukaemia, the corresponding cisplatin resistant line, and a human ovarian cell line, SKOV-3. However, initial in vivo testing against a solid mouse plasmacytoma (PC6) and P388 leukaemia has not revealed significant activity.