Coexistence of Two Different Distorted Octahedral [MnF6]3− Sites in K3[MnF6]: Manifestation in Spectroscopy and Magnetism. Issue 38 (28th May 2021)

• Record Type: Journal Article
• Authors: Stoll, Christiane; Atanasov, Mihail; Bandemehr, Jascha; Neese, Frank; Pietzonka, Clemens; Kraus, Florian; Karttunen, Antti J.; Seibald, Markus; Heymann, Gunter; Huppertz, Hubert
• Is Part Of: Chemistry. Volume 27:Issue 38(2021)
• Page Start: 9801
• Page End: 9813
• Publication Date: 2021-05-28
• Subjects: ab initio calculations -- fluorides -- single-crystal determination -- solid-state reactions; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.202005496
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: As a consequence of the static Jahn‐Teller effect of the 5 E ground state of Mn III in cubic structures with octahedral parent geometries, their octahedral coordination spheres become distorted. In the case of six fluorido ligands, [MnF6 ] 3− anions with two longer and four shorter Mn−F bonds making elongated octahedra are usually observed. Herein, we report the synthesis of the compound K3 [MnF6 ] through a high‐temperature approach and its crystallization by a high‐pressure/high‐temperature route. The main structural motifs are two quasi‐isolated, octahedron‐like [MnF6 ] 3− anions of quite different nature compared to that met in ideal octahedral Mn III Jahn‐Teller systems. Owing to the internal electric field of Ci symmetry dominated by the next‐neighbour K + ions acting on the Mn III sites, both sites, the pseudo‐rhombic (site 1) and the pseudo‐tetragonally elongated (site 2) [MnF6 ] 3− anions are present in K3 [MnF6 ]. The compound was characterized by single‐crystal and powder X‐ray diffraction, and magnetometry as well as by FTIR, Raman, and ligand field spectroscopy. A theoretical interpretation of the electronic structure and molecular geometry of the two Mn sites in the lattice is given by using a vibronic coupling model with parameters adjusted from multireference ab‐initio cluster calculations. Abstract : Distorted octahedra : Using a high‐temperature/high‐pressure synthesis, K3 [MnF6 ] with two different kinds of distorted [MnF6 ] 3− octahedra – a pseudo‐rhombic and an pseudo‐tetragonally elongated distorted octahedron – was structurally, magnetically and spectroscopically characterized. A theoretical interpretation of the electronic structure and molecular geometry is given.