Abstract: Five novelcomplexesofformula 〔Ln( pfpr)3〕2 NITRS·nH2 O, where Ln = Nd, Sm , Eu, Gd, Dy; pfpr= pentafluoropropionate; NITRS= 2 - (2’- thienyl) - 4,4 ,5 ,5 te tramethylimidazoline 1 oxyl 3 oxide, and n= 6(for Nd);4(for Eu and Gd) ;2(for Sm and Dy), have been synthesized. Thesecomplexes werecharacterized by elemental analysis, IR, electronicspectra and EPR. Thevariabletemperature(2 300 K) magneticsusceptibility ofthecomplex 〔Gd(pfpr)3〕2 NITRS·4 H2 Owas determined and discussed. Theexchange integral,J= 0 44 cm 1 , wasfoundtobepositive,indicating a weakferromagneticspin ex changeinteraction between theradicaland Gd(III) ion.

Key words: ferromagnetism , Lanthanideion, nitronylnitroxide, complex