Rh2(CF3CONH) 4: The First Biological Assays of a Rhodium (II) Amidate

The rhodium (II) complexes Rh(2)(tfa)(4).2(tfac) and Rh(2)(tfacam)(4) (tfacam = CF(3)CONH-,tfa = CF(3)COO-,tfac = CF(3)CONH(2)) were synthesized and characterized by microanalysis and electronic and vibrational spectroscopies. Rh(2)(tfacam)(4) was tested both in vitro (U937 and K562 human leukemia cells and Ehrlich ascitic tumor cells) and in vivo for cytostatic activity and lethal dose determination, respectively. This is the first rhodium tetra-amidate to have its biological activity evaluated. The LD(50) value for Rh(2)(tfacam)(4) is of the same order as that of cisplatin, and it was verified that the rhodium complex usually needs lower doses than cisplatin to promote the same inhibitory effects.