The series of ferrocene-containing tris-beta-diketonato aluminum(III) complexes [Al(FcCOCHCOR)(3)] (R = CF3, 1; CH3, 2; C6H5, 3; and Fc = ferrocenyl = Fe(eta(5)-C5H5(eta(5)-C5H4), 4) were synthesized and investigated structurally and electro-chemically; complex 1 was subjected to cytotoxicity tests. H-1 NMR-spectroscopy distinguished between the mer and fac isomers of 2 and 3. Complex 1 existed only as the mer isomer. A single crystal X-ray crystallographic determination of the structure of a merisomer of Al(FcCOCHCOCF(3))(3), 1, (Z = 4, space group P2(1)2(1)2(1)) demonstrated extensive delocalization of all bonds which explained the pronounced electrochemically observed intramolecular communication between molecular fragments. In contrast to electrochemical studies in CH2Cl2/[N(Bu-n)(4)][PF6],the use of the supporting electrolyte [N(Bu-n)(4)][B(C6F5)(4)] allowed identification of all Fc/Fc(+) electrochemical couples by cyclic and square wave voltammetry for 1-4. For R = Fc, formal reduction potentials of the six ferrocenyl groups were found to be E-o' = 33, 123, 304, 432, 583, and 741 mV versus free ferrocene respectively. Complex 1 (IC50 = 10.6 mu mol dm(-3)) was less cytotoxic than the free FcCOCH(2)COCF(3) ligand having IC50 = 6.8 mu mol dm(-3) and approximately 2 orders of magnitude less toxic to human HeLa neoplastic cells than cisplatin (IC50 = 0.19 mu mol dm(-3)).