Magnetic anisotropy and structural flexibility in the field-induced single ion magnets [Co{(OPPh2)(EPPh2)N}2], E = S, Se, explored by experimental and computational methods

Eleftherios Ferentinos; Demeter Tzeli; Silvia Sottini; Edgar J J Groenen; Mykhaylo Ozerov; Giordano Poneti; Kinga Kaniewska-Laskowska; J Krzystek; Panayotis Kyritsis

doi:10.1039/d2dt03335f

Magnetic anisotropy and structural flexibility in the field-induced single ion magnets [Co{(OPPh₂)(EPPh₂)N}₂], E = S, Se, explored by experimental and computational methods

Dalton Trans. 2023 Feb 14;52(7):2036-2050. doi: 10.1039/d2dt03335f.

Authors

Eleftherios Ferentinos¹, Demeter Tzeli^{2

3}, Silvia Sottini⁴, Edgar J J Groenen⁴, Mykhaylo Ozerov⁵, Giordano Poneti⁶, Kinga Kaniewska-Laskowska⁷, J Krzystek⁵, Panayotis Kyritsis¹

Affiliations

¹ Inorganic Chemistry Laboratory, Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis, GR-15771 Athens, Greece. kyritsis@chem.uoa.gr.
² Physical Chemistry Laboratory, Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis, GR-15771 Athens, Greece.
³ Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, 48 Vassileos Constantinou Ave., GR-11635 Athens, Greece.
⁴ Huygens-Kamerlingh Onnes Laboratory, Department of Physics, Leiden University, Niels Bohrweg 2, 2333 CA Leiden, The Netherlands.
⁵ National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA. krzystek@magnet.fsu.edu.
⁶ Instituto de Química, Universidade Federal do Rio de Janeiro, 21941-909 Rio de Janeiro, Brazil. gponeti@iq.ufrj.br.
⁷ Department of Inorganic Chemistry, Faculty of Chemistry, Gdańsk University of Technology, G. Narutowicza St. 11/12, Gdańsk PL-80-233, Poland.

Abstract

During the last few years, a large number of mononuclear Co(II) complexes of various coordination geometries have been explored as potential single ion magnets (SIMs). In the work presented herein, the Co(II) S = 3/2 tetrahedral [Co{(OPPh₂)(EPPh₂)N}₂], E = S, Se, complexes (abbreviated as CoO2E2), bearing chalcogenated mixed donor-atom imidodiphosphinato ligands, were studied by both experimental and computational techniques. Specifically, direct current (DC) magnetometry provided estimations of their zero-field splitting (zfs) axial (D) and rhombic (E) parameter values, which were more accurately determined by a combination of far-infrared magnetic spectroscopy and high-frequency and -field EPR spectroscopy studies. The latter combination of techniques was also implemented for the S = 3/2 tetrahedral [Co{(EPⁱPr₂)₂N}₂], E = S, Se, complexes, confirming the previously determined magnitude of their zfs parameters. For both pairs of complexes (E = S, Se), it is concluded that the identity of the E donor atom does not significantly affect their zfs parameters. High-resolution multifrequency EPR studies of CoO2E2 provided evidence of multiple conformations, which are more clearly observed for CoO2Se2, in agreement with the structural disorder previously established for this complex by X-ray crystallography. The CoO2E2 complexes were shown to be field-induced SIMs, i.e., they exhibit slow relaxation of magnetization in the presence of an external DC magnetic field. Advanced quantum-chemical calculations on CoO2E2 provided additional insight into their electronic and structural properties.