The reactivity of the new flexible potentially pentadentate
N3O2 aminophenol ligand H
4L
r (2,2′-((pyridine-2,6-diylbis(methylene))bis(azanediyl))diphenol) towards different dysprosium salts and holmium(III) nitrate was investigated. Accordingly, this reactivity seems to greatly depend on the metal ion and salt employed. In
[...] Read more.
The reactivity of the new flexible potentially pentadentate
N3O2 aminophenol ligand H
4L
r (2,2′-((pyridine-2,6-diylbis(methylene))bis(azanediyl))diphenol) towards different dysprosium salts and holmium(III) nitrate was investigated. Accordingly, this reactivity seems to greatly depend on the metal ion and salt employed. In this way, the reaction of H
4L
r with dysprosium(III) chloride in air leads to the oxo-bridged tetranuclear complex [Dy
4(H
2L
r)
3(Cl)
4(μ
3-O)(EtOH)
2(H
2O)
2]·2EtOH·H
2O (
1·2EtOH·H
2O), while the same reaction just changing the chloride salt by the nitrate one renders the peroxo-bridged pentanuclear compound [Dy
5(H
2L
r)
2(H
2.5L
r)
2(NO
3)
4(µ
3-O
2)
2]·2H
2O (
2·2H
2O), where both peroxo ligands seem to come from the fixation and reduction of atmospheric oxygen. However, if holmium(III) nitrate is used instead of dysprosium(III) nitrate, no evidence of a peroxide ligand is observed, and the dinuclear complex {[Ho
2(H
2L
r)(H
3L
r)(NO
3)
2(H
2O)
2](NO
3)} 2.5H
2O (
3·2.5H
2O) is isolated. The three complexes were unequivocally characterized by X-ray diffraction techniques, and their magnetic properties were analyzed. Thus, while the Dy
4 and Ho
2 complexes do not show magnet-like behavior even in the presence of an external magnetic field,
2·2H
2O is a single molecule magnet, with an
Ueff barrier of 61.2 K (43.2 cm
−1). This is the first homonuclear lanthanoid peroxide SMM, which also shows the highest barrier among the reported 4f/3d peroxide zero field SMMs to date.
Full article
