A cytotoxic bis(carbene) gold(I) complex of ferrocenyl complexes: synthesis and structural characterisation

The N-heterocyclic carbene (NHC) precursors 1-[(E)-2-butenyl]-3-(4-ferrocenylphenyl)imidazolium bromide (2) and 1-[(E)-2-butenyl]-3-(4-ferrocenylphenyl)imidazolium tetrafluoroborate (3) were derived from 1-(4-ferrocenylphenyl) imidazole ferrocenyl complex 3 reacts with Ag2O and chloro(dimethylsulfide)gold(I) in the presence of tetraethylammonium chloride to produce the mixed metal species bis{1-[(E)-2-butenyl]-3-(4-ferrocenylphenyl)-2H-imidazol-2-ylidene}gold(I) tetra fluoroborate (4). Single crystal X-ray structure analyses of 1, 3 and 4 indicate that the NCHN-hydrogen in 3 is hydrogen bonded to the BF4-anion [C(H1). . . F, 3.265(4) angstrom], as is also reflected in the position of its H-1 NMR chemical shift. Cytotoxicity studies show that complex 4 is selective for cancer cells and active against the tumour cell lines Jurkat and MCF 7.