Magnetic Anisotropy of Tetrahedral Co II Single-Ion Magnets: Solid-State Effects

• Published in: Inorganic chemistry Vol. 55; no. 19; pp. 9537 - 9548
• Main Authors: Sottini, Silvia, Poneti, Giordano, Ciattini, Samuele, Levesanos, Nikolaos, Ferentinos, Eleftherios, Krzystek, J, Sorace, Lorenzo, Kyritsis, Panayotis
• Format: Journal Article
• Language: English
• Published: United States 03-10-2016
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/acs.inorgchem.6b00508

This study reports the static and dynamic magnetic characterization of two mononuclear tetrahedral Co
complexes, [Co{
Pr
P(E)NP(E)
Pr
}
], where E = S (CoS
) and Se (CoSe
), which behave as single-ion magnets (SIMs). Low-temperature (15 K) single-crystal X-ray diffraction studies point out that the two complexes exhibit similar structural features in their first coordination sphere, but a disordered peripheral
Pr group is observed only in CoS
. Although the latter complex crystallizes in an axial space group, the observed structural disorder leads to larger transverse magnetic anisotropy for the majority of the molecules compared to CoSe
, as confirmed by electron paramagnetic resonance spectroscopy. Static magnetic characterization indicates that both CoS
and CoSe
show easy-axis anisotropy, with comparable D values (∼-30 cm
). Moreover, alternating-current susceptibility measurements on these Co
complexes, magnetically diluted in their isostructural Zn
analogues, highlight the role of dipolar magnetic coupling in the mechanism of magnetization reversal. In addition, our findings suggest that, despite their similar anisotropic features, CoS
and CoSe
relax magnetically via different processes. This work provides experimental evidence that solid-state effects may affect the magnetic behavior of SIMs.