We present EPR and Susceptibility measurements performed on the perovs
kite-like family CanFe2Mnn-2O3n-1. On going from n=2 to n=3 Fe3(+) is
progressively replaced by Mn4+. As a consequence the ordering temperat
ure is depressed and frustrations in the magnetic interactions were fo
und. 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 exch
ange interactions.