Exchange Interactions and Magnetic Properties of a Molecular Mn18 -Ring Complex
Jascha Bandemehr1, Mihail Atanasov2, Shashank Vittal Rao2
1Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Str. 4, 35032, Marburg, Germany.
Abstract:
[Mn3 O(OAc)7 (HOAc)]6 ⋅ x AcOH (x=6-9) represents a rare example of a compound containing molecular Mn18 -rings. These are formed by Mn3 (μ3 -O) subunits in which the high-spin Mn(III) centers are bridged by three pairs of acetate anions (AcO- ). An AcOH molecule coordinates to one of the Mn atoms leading to [Mn3 (μ3 -O)(μ2 -OAc)6 (AcOH)]-units, designated in short as Mn3 -units, that are interconnected by acetate anions via the other two Mn atoms to form Mn18 -rings. Magnetic measurements show weak ferromagnetic interactions between them that are suppressed in strong magnetic field. Quantum-chemical calculations on Mn3 model complexes using independently DFT and ab-initio multi reference methods (CASSCF/NEVPT2) show a correlation between the orientation of the pseudo-Jahn-Teller axes of pairs of Mn(III) magnetic centers and corresponding exchange coupling energies. Weak coupling between Mn3 -units within the Mn18 -ring allowed to simulate the magnetic susceptibility versus temperature dependence in terms of basically uncoupled magnetic moments of each Mn3 -unit within the ring.
More Related Videos
07:24Paramagnetic Relaxation Enhancement for Detecting and Characterizing Self-Associations of Intrinsically Disordered Proteins
Published on: September 23, 2021
07:42Optimizing Magnetic Force Microscopy Resolution and Sensitivity to Visualize Nanoscale Magnetic Domains
Published on: July 20, 2022
Related Concept Videos
Colors and Magnetism
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human...
Valence Bond Theory
Atomic Nuclei: Nuclear Relaxation Processes
NMR Spectroscopy: Spin–Spin Coupling
π Electron Effects on Chemical Shift: Aromatic and Antiaromatic Compounds
Crystal Field Theory - Octahedral Complexes
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
