Synthesis, Structure of Nitrogen-Containing Phosphinogold(I) Ferrocenes. In vitro Activity against Bladder and Colon Carcinoma Cell Lines

The gold salt [(tht)AuCl] was reacted with [1-N,N-dimethylaminométhyl-2-diphenylphosphino]ferrocene (1) forming the bimetallic derivative 4. The reaction of methyl iodide and tetramethylammonium bromide on the chloride 4 produced the ammonium salt 5 and the bromide 6 respectively. New aminophosphines 2 and 3, which represent two of the rare phosphorylated metallocenes containing P(III)-N bond have also been coordinated to gold(I) to form 7 and 8. The presence of the ethoxy group in 7 provides evidence for the lability of one nitrogen-phosphorus bond. The X-ray structure of compounds 4 and 7 have been established. Both crystallize in space group P2(1)/c, monoclinic, with a = 11.095(2) Å, b = 12.030(3) Å, c = 17.763(4) Å, β= 94.02(2)∘, Z = 4 for 4 and a = 14.863(3) Å, b = 8.036(5)Å, c = 18.062(5)Å, β =101.64(1)°, Z = 4 for 7. (197)Au Mössbauer data are in good agreement with those for other linear P-Au-Cl containing complexes. The compounds were evaluated for in vitro anti-tumour activity against two human tumours. Differential cytotoxicity was observed with activity comparable to cisplatin, with the exception of one compound which was significantly more cytotoxic.