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Role of Coordination Number and Geometry in Controlling the Magnetic Anisotropy in Fe II , Co II , and Ni II Single‐Ion Magnets
Author(s) -
Sarkar Arup,
Dey Sourav,
Rajaraman Gopalan
Publication year - 2020
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.202003211
Subject(s) - anisotropy , magnetic anisotropy , lanthanide , ion , ab initio quantum chemistry methods , magnetization , transition metal , magnet , magnetic moment , ab initio , condensed matter physics , materials science , crystallography , chemistry , magnetic field , physics , molecule , biochemistry , organic chemistry , quantum mechanics , catalysis
Since the last decade, the focus in the area of single‐molecule magnets (SMMs) has been shifting constructively towards the development of single‐ion magnets (SIMs) based on transition metals and lanthanides. Although ground‐breaking results have been witnessed for Dy III ‐based SIMs, significant results have also been obtained for some mononuclear transition metal SIMs. Among others, studies based on Co II ion are very prominent as they often exhibit high magnetic anisotropy or zero‐field splitting parameters and offer a large barrier height for magnetisation reversal. Although Co II possibly holds the record for having the largest number of zero‐field SIMs known for any transition metal ion, controlling the magnetic anisotropy in these systems are is still a challenge. In addition to the modern spectroscopic techniques, theoretical studies, especially ab initio CASSCF/NEVPT2 approaches, have been used to uncover the electronic structure of various Co II SIMs. In this article, with some selected examples, the aim is to showcase how varying the coordination number from two to eight, and the geometry around the Co II centre alters the magnetic anisotropy. This offers some design principles for the experimentalists to target new generation SIMs based on the Co II ion. Additionally, some important Fe II /Fe III and Ni II complexes exhibiting large magnetic anisotropy and SIM properties are also discussed.