A Novel Family of Triangular Co^II₂Ln^III and Co^II₂Y^III Clusters by the Employment of Di-2-Pyridyl Ketone

Abstract

The synthesis, structural characterization and magnetic study of novel CoII/4f and CoII/YIII clusters are described. In particular, the initial employment of di-2-pyridyl ketone, (py)2CO, in mixed metal Co/4f chemistry, provided access to four triangular clusters, [CoII2MIII{(py)2C(OEt)(O)}4(NO3)(H2O)]2[M(NO3)5](ClO4)2 (M = Gd, 1; Dy, 2; Tb, 3; Y, 4), where (py)2C(OEt)(O)− is the monoanion of the hemiketal form of (py)2CO. Clusters 1−4 are the first reported Co/4f (1−3) and Co/Y (4) species bearing (py)2CO or its derivatives, despite the fact that over 200 metal clusters bearing this ligand have been reported so far. Variable-temperature, solid-state dc and ac magnetic susceptibility studies were carried out on 1−4 and revealed the presence of weak ferromagnetic exchange interactions between the metal ions (JCo-Co = +1.3 and +0.40 cm−1 in 1 and 4, respectively; JCo-Gd = +0.09 cm−1 in 1). The ac susceptibility studies on 2 revealed nonzero, weak out-of-phase (χ’’M) signals below ~5 K.

Keywords

• 3d/4f metal clusters
• di-2 pyridyl ketone
• magnetism
• cobalt
• lanthanides
• mixed metal Co/Ln clusters