title: Magnetic Anisotropy of Tetrahedral CoIISingle-Ion Magnets: Solid-State Effects.
abstract: This study reports the static and dynamic magnetic characterization of two mononuclear tetrahedral CoIIcomplexes, [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 peripheraliPr 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 CoS4and CoSe4show easy-axis anisotropy, with comparable D values (∼-30 cm-1). Moreover, alternating-current susceptibility measurements on these CoIIcomplexes, magnetically diluted in their isostructural ZnIIanalogues, highlight the role of dipolar magnetic coupling in the mechanism of magnetization reversal. In addition, our findings suggest that, despite their similar anisotropic features, CoS4and CoSe4relax magnetically via different processes. This work provides experimental evidence that solid-state effects may affect the magnetic behavior of SIMs.
authors.affiliation: Department of Chemistry "Ugo Schiff" and INSTM Research Unit of Florence, University of Florence , via della Lastruccia 3-13, 50019 Sesto Fiorentino, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Sottini
authors.affiliation: Department of Chemistry "Ugo Schiff" and INSTM Research Unit of Florence, University of Florence , via della Lastruccia 3-13, 50019 Sesto Fiorentino, Italy.
authors.forename: Giordano
authors.initials: G
authors.lastname: Poneti
authors.affiliation: Centro Interdipartimentale di Crystallografia Strutturale CRIST, University of Florence , via della Lastruccia 5, 50019 Sesto Fiorentino, Italy.
authors.forename: Samuele
authors.initials: S
authors.lastname: Ciattini
authors.affiliation: Inorganic Chemistry Laboratory, Department of Chemistry, National and Kapodistrian University of Athens , Panepistimiopolis, GR-15771 Athens, Greece.
authors.forename: Nikolaos
authors.initials: N
authors.lastname: Levesanos
authors.affiliation: Inorganic Chemistry Laboratory, Department of Chemistry, National and Kapodistrian University of Athens , Panepistimiopolis, GR-15771 Athens, Greece.
authors.forename: Eleftherios
authors.initials: E
authors.lastname: Ferentinos
authors.affiliation: National High Magnetic Field Laboratory (NHMFL), Florida State University , Tallahassee, Florida 32310, United States.
authors.forename: J
authors.initials: J
authors.lastname: Krzystek
authors.affiliation: Department of Chemistry "Ugo Schiff" and INSTM Research Unit of Florence, University of Florence , via della Lastruccia 3-13, 50019 Sesto Fiorentino, Italy.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Sorace
authors.affiliation: Inorganic Chemistry Laboratory, Department of Chemistry, National and Kapodistrian University of Athens , Panepistimiopolis, GR-15771 Athens, Greece.
authors.forename: Panayotis
authors.initials: P
authors.lastname: Kyritsis