It is interesting to relate this observation with that of a study of the influence of the inner coordination sphere of cobalt and ruthenium hexamine on their interaction with thymus DNA in solution. This study showed that the hydrodynamic radius of ruthenium is much larger than that of cobalt [Rh (Co3) = 65 ± 5 nm and Rh (Ru3) = 440 ± 30 nm] although the two compounds exert an identical global influence on the structure of the macromolecule [30]