“…However, the half maximal inhibitory concentration (IC 50 ) values in cancer cells for these compounds are generally high (> 100 μM), which is attributed to the high reactivity of these complexes, as a result of the low stability in organic solvents or under physiological conditions. [20][21][22][23] In addition, there are many papers 22,23 which currently report the use of monophosphines or monopyridines as the "X" ligand, resulting in complexes with high toxicity (< 5 μM), thanks to the lipophilicity enhancement of the compounds, when at least one of these molecules is present in their structures. Furthermore, when "L−L" is N−N, [24][25][26] P−P, [27][28][29][30][31][32] N−S, 33,34 N−O, 24,31,32 O−O 24,35,36 donor ligand, a wide range of IC 50 values is obtained.…”