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

trova@unifi(opens in a new window)|View at Publisher| Export | Download | Add to List | More... Inorganic Chemistry Volume 55, Issue 19, 3 October 2016, Pages 9537-9548 Magnetic Anisotropy of Tetrahedral CoII Single-Ion Magnets: Solid-State Effects (Article) Sottini, S.a, Poneti, G.a , Ciattini, S.b, Levesanos, N.c, Ferentinos, E.c, Krzystek, J.d, Sorace, L.a, Kyritsis, P.c a Department of Chemistry Ugo Schiff, INSTM Research Unit of Florence, University of Florence, via della Lastruccia 3-13, Sesto Fiorentino, Italy b Centro Interdipartimentale di Crystallografia Strutturale CRIST, University of Florence, via della Lastruccia 5, Sesto Fiorentino, Italy c Inorganic Chemistry Laboratory, Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis, Athens, Greece View additional affiliations View references (118) Abstract This study reports the static and dynamic magnetic characterization of two mononuclear tetrahedral CoII complexes, [Co{iPr2P(E)NP(E)iPr2}2], where E = S (CoS4) and Se (CoSe4), 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 iPr group is observed only in CoS4. 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 CoSe4, as confirmed by electron paramagnetic resonance spectroscopy. Static magnetic characterization indicates that both CoS4 and CoSe4 show easy-axis anisotropy, with comparable D values (â14 â30 cm-1). Moreover, alternating-current susceptibility measurements on these CoII complexes, magnetically diluted in their isostructural ZnII 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, CoS4 and CoSe4 relax magnetically via different processes. This work provides experimental evidence that solid-state effects may affect the magnetic behavior of SIMs.