We present EPR and Susceptibility measurements performed on the perovskite-like family CanFe2Mnn-2O3n-1. On going from n=2 to n=3 Fe3+ is progressively replaced by Mn4+. As a consequence the ordering temperature is depressed and frustrations in the magnetic interactions were found. The measurements are compared with the previously studied system CanFe2Tin-2O3n-1, where magnetic Mn4+ were replaced by non magnetic Ti4+. We discuss the results in terms of cationic ordering and super exchange interactions
