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Unequivocal Synthetic Pathway to Heterodinuclear (4f,4f′) Complexes: Magnetic Study of Relevant (Ln III , Gd III ) and (Gd III , Ln III ) Complexes
Author(s) -
Costes JeanPierre,
Nicodème Franck
Publication year - 2002
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/1521-3765(20020802)8:15<3442::aid-chem3442>3.0.co;2-z
Subject(s) - lanthanide , ionic radius , crystallography , chemistry , ion , antiferromagnetism , population , ligand (biochemistry) , physics , biochemistry , demography , receptor , organic chemistry , sociology , condensed matter physics
The tripodal ligand tris[4‐(2‐hydroxy‐3‐methoxyphenyl)‐3‐aza‐3‐buten]amine (LH 3 ) is capable of coordinating to two different lanthanide ions to give complexes formulated as [LLnLn′(NO 3 ) 3 ]⋅ x H 2 O. The stepwise synthetic procedure consists of introducing first a Ln III ion in the inner N 4 O 3 coordination site. The isolated neutral complex LLn is then allowed to react with a second and different Ln′ ion that occupies the outer O 6 site, thus yielding a [LLnLn′(NO 3 ) 3 ]⋅ x H 2 O complex. A FAB + study has confirmed the existence of (Ln, Ln′) entities as genuine, when the Ln′ ion in the outer site has a larger ionic radius than the Ln ion in the inner site. The qualitative magnetic study of the (Gd, Ln) and (Ln, Gd) complexes, based on the comparison of the magnetic properties of (Gd, Ln) (or (Ln, Gd)) pairs and (Y, Ln) (or (Ln, La)) pairs, is very informative. Indeed, these former complexes are governed by the thermal population of the Ln III Stark levels and the Ln–Gd interaction, while the latter are influenced by the thermal population of the Ln III Stark levels. We have been able to show that a ferromagnetic interaction exists at low temperature in the (Gd, Nd), (Gd, Ce), and (Yb, Gd) complexes. In contrast, an antiferromagnetic interaction occurs in the (Dy, Gd) and (Er, Gd) complexes. Although we cannot give a quantitative value to these interactions, we can affirm that their magnitudes are weak since they are only perceptible at very low temperature.