title: Structural Dependence of the Ising-type Magnetic Anisotropy and of the Relaxation Time in Mononuclear Trigonal Bipyramidal Co(II) Single Molecule Magnets.
abstract: This paper describes the correlation between Ising-type magnetic anisotropy and structure in trigonal bipyramidal Co(II) complexes. Three sulfur-containing trigonal bipyramidal Co(II) complexes were synthesized and characterized. It was shown that we can engineer the magnitude of the Ising anisotropy using ligand field theory arguments in conjunction with structural parameters. To prepare this series of compounds, we used, on the one hand, a tetradentate ligand containing three sulfur atoms and one amine (NS3tBu) and on the other hand three different axial ligands, namely, Cl-, Br-, and NCS-. The organic ligand imposes a trigonal bipyramidal arrangement with the three sulfur atoms lying in the trigonal plane with long Co-S bond distances. The magnetic properties of the compounds were measured, and ab initio calculations were used to analyze the anisotropy parameters and perform magneto-structural correlations. We demonstrate that a smaller axial zero-field splitting parameter leads to slower relaxation time when the symmetry is strictly axial, while the presence of very weak rhombicity decreases the energy barrier and speeds the relaxation of the magnetization.
authors.affiliation: Institut de Chimie Moléculaire et des Matériaux d'Orsay, CNRS, Université Paris Sud, Université Paris Saclay , 91405 Orsay Cedex, France.
authors.forename: Feng
authors.identifier: http://orcid.org/0000-0002-6518-1274
authors.initials: F
authors.lastname: Shao
authors.affiliation: Institut de Chimie Moléculaire et des Matériaux d'Orsay, CNRS, Université Paris Sud, Université Paris Saclay , 91405 Orsay Cedex, France.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Cahier
authors.affiliation: Institut de Chimie Moléculaire et des Matériaux d'Orsay, CNRS, Université Paris Sud, Université Paris Saclay , 91405 Orsay Cedex, France.
authors.forename: Eric
authors.initials: E
authors.lastname: Rivière
authors.affiliation: Institut de Chimie Moléculaire et des Matériaux d'Orsay, CNRS, Université Paris Sud, Université Paris Saclay , 91405 Orsay Cedex, France.
authors.forename: Régis
authors.initials: R
authors.lastname: Guillot
authors.affiliation: Laboratiore de Chimie et Physique Quantiques, Université Toulouse III , 118 route de Narbonne, 31062 Toulouse, France.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Guihéry
authors.affiliation: Institut de Chimie Moléculaire et des Matériaux d'Orsay, CNRS, Université Paris Sud, Université Paris Saclay , 91405 Orsay Cedex, France.
authors.forename: Victoria E
authors.identifier: http://orcid.org/0000-0002-6469-5759
authors.initials: VE
authors.lastname: Campbell
authors.affiliation: Institut de Chimie Moléculaire et des Matériaux d'Orsay, CNRS, Université Paris Sud, Université Paris Saclay , 91405 Orsay Cedex, France.
authors.forename: Talal
authors.initials: T
authors.lastname: Mallah