A new complex, [Fe(acac)L-2], bearing inidazolidine nitroxyl-free radical l
igand (L-) was recently synthesised for biological studies. It proved to be
biologically active against African sleeping sickness, plasmodium falcipar
um (malaria), leishmaniasis and chaga disease causative agents. Three ESR w
ell resolved peaks indicated the presence of a free (unpaired) and chemical
ly active electron in the complex. The structural complex ferric iron was f
ound at the centre of two electric gradient whose the biggest is suggested
to be initiated by the unpaired charge. No distinction between different ci
s isomers could be made.