High-Field EPR Investigation and Detailed Modeling of the Magnetoanisotropy Tensor of an Unusual Mixed-Valent Mn2IVMn2IIIMnII Cluster

• Published in: Applied magnetic resonance 2023, Vol.54 (1), p.77-91
• Main Authors: Wang, Xiaoling, Hale, Ashlyn R., Hill, Stephen, Christou, George
• Format: Article
• Language: English
• Subjects: Atoms and Molecules in Strong Fields; Clusters; Crystal structure; Electron paramagnetic resonance; Electrons; Fine structure; Jahn-Teller effect; Laser Matter Interaction; Magnetic anisotropy; Magnetic fields; Organic Chemistry; Original Paper; Oxidation; Physical Chemistry; Physics; Physics and Astronomy; Simulation; Solid State Physics; Spectroscopy/Spectrometry; Splitting; Temperature; Tensors
• ISSN: 0937-9347; 1613-7507
• DOI: 10.1007/s00723-022-01517-4

Multifrequency (128 and 256 GHz) high-field electron paramagnetic resonance measurements up to 14.5 T over the temperature range 8.0 to 30.0 K were performed on powder samples of a recently reported salt of the cluster cation [Mn 5 O 4 (phth) 3 (phthH)(bpy) 4 ] + ( 1 ; Mn 2 IV Mn 2 III Mn II ). Spectral simulations were performed to quantify the zero-field splitting parameters of 1 , further supporting the previously assigned S  =  7 / 2 ground state. 1 possesses a highly biaxial zero-field splitting tensor ( E/D  = 0.227) with overall easy-plane anisotropy ( D  > 0) arising from the near-perpendicular angle between the Jahn–Teller axes of the two Mn III that contribute a majority of the magnetic anisotropy. A microscopic model has been developed that relates the sign of D and the degree of ortho-rhombicity, E/D , to the angle between the two Jahn–Teller axes. The additional fine structure and peak-splitting features not represented by the simulations were attributed to population of excited states or the weak intermolecular interactions previously observed in the crystal structure.