Two europium (III) complexes (3 and 4) have been obtained reacting europium (III) nitrate and two polychlorotriphenylmethyl radicals properly functionalized with one (PTMMC−, 1) and six (PTMHC6−, 2) carboxylate groups, respectively. While complex 3 reveals a lamellar polar–apolar separated ion pair structure alternating PTM-based bilayers with nonaaquaeuropium cations ([Eu(H2O)9](PTMMC)3(PTMMCH)3 · 7H2O · 6EtOH), complex 4 shows a one-dimensional chain-like structure with formula [Eu2(PTMHC)(H2O)13] · 16H2O · EtOH. Magnetic properties of both complexes were studied in the 2–300 K range, and show the presence of weak inter-radical antiferromagnetic interactions below 5 K. ; This work was supported by the Ministerio de Educación y Ciencia of Spain under Consolider (project EMOCIONa, CTQ2006-06333/BQU), by EU under a Marie Curie Research Training Network (contract “QuEMolNa” number MCRTN-CT-2003-504880), as well as by NOE MAGMANET (Contract 515767-2). N.R. thanks the MCRTN for his postdoctoral contract. A.D. is grateful to the MCRTN for a predoctoral grant. D.M. acknowledges the Ministerio de Ciencia y Tecnologia of Spain for a Ramón y Cajal contract, and S.P. thanks the Ministerio de Ciencia y Tecnologia for a postdoctoral fellowship. ; Peer Reviewed