A genuine and original trinuclear gadolinium complex in which the three Gd centers are linked by three different phenolato or hydroxo bridges presents an antiferromagnetic interaction of 0.19cm(-1). This J value is among the largest ones found for interacting Gd centers.
Use of Gd-155 Mifissbauer spectroscopy allows a straightforward characterization of heterodinuclear Ln-Ln' complexes (LLnLn' (NO3)(3)center dot(H2O)(2)) with a tripodal ligand L, possessing two different N4O3 and O3O3 coordination sites. Thanks to the isomer shift value, the location of the Gd-III ion is confirmed; the Gd atom in the Gd-Ln' series (Ln' = Ce, Nd, Eu) occupies the inner N4O3 site with a eight-coordination (N4O3 + O), but on the other hand the Gd atom in the Ln-Gd series (Ln = Dy, Er, Yb) resides in the outer O3O3 site with a ten-coordination (O3O3 + O-2 + O-2). The smaller isomer shift values for the former indicate that coordination of the basic nitrogen atoms enhances the 6s orbital population. With the help of Eu-151 Mossbauer spectroscopy, we demonstrate that the Gd-Eu entity is a genuine heterodinuclear complex, in which the Gd-III ion is located in the inner site and the Eu-III ion in the outer oxygenated site. This result highlights the feasibility of our synthetic process described earlier to introduce in a heterodinuclear complex two consecutive ions of the periodic table. And the slow paramagnetic relaxation observed in the Er-166 Mossbaner spectrum of the Er-Gd complex confirms presence of a magnetic interaction in the genuine Er-Gd complex. (C) 2019 Elsevier Ltd. All rights reserved.