Temperature Independent Isotropic EPR Spectra of [(CH₃)₄N]₂MnCl₄ and [(CH₃)₄N]₂FeCl₄ Single Crystals

Abstract

Electron paramagnetic resonance of [(CH3) 4 N] 2 MnCl 4 and [(CH 3 ) 4 N] 2 FeCl 4 single crystals was studied between 20 and 400 K. The peak-to-peak derivative linewidths of these crystals seem not to change in this temperature interval and approximately 100 mT for [(CH 3 ) 4 N] 2 MnCl 4 and -20 mT for [(CH 3 ) 4 N] 2 FeCl 4 . The spectra were found to be isotropic, with g = 2.0039 for [(CH 3 ) 4 N] 2 MnCl 4 and g = 2.0042 for [(CH 3 ) 4 N] 2 FeCl 4 . This temperature independence is attributed to isotropic strong exchange interactions of Mn 2+ and Fe 2+ nuclei, and it seems that hindered rotation of the MnCl 4 " and FeCl 4 " tetrahedra does not occur in this temperature interval.

Tunable Dielectric Switching of (Quinuclidinium)[MnCl4] Hybrid Compounds

“…The EPR spectra of powdered QMnCl (presented in Figure ) consist of a strong line with g -factor g = 2.01 and very weak satellite lines from fine structure, clearly visible at Phase II. In some cases, a strong dipole broadening and/or exchange interaction between Mn 2+ ( S = 5/2, I = 5/2) ions may smear the fine structure and EPR spectra consist of only a single line, as shown before. , On the other hand, if the symmetry of the Mn-coordinating environment is not high and the dipole broadening is small enough, a fine structure can still be observed . The last case corresponds to our EPR studies and is consistent with the X-ray data (Figure ).…”

Crystal structure of imidazo[1,5-a]pyridinium-based hybrid salt (C13H12N3)2[MnCl4]

“…ZFS is highly sensitive to the coordination environment of the metal ion and if all bonds in the MnCl 4 tetrahedron are equal, one may expect only a strong and broadened single resonance line at g = 2 recorded in the EPR spectra. Indeed, one isotropic line with an unchanged linewidth of about 100 mT and a g-value of 2.0039 was observed in the X-band EPR spectrum of the organic-inorganic hybrid [(CH 3 ) 4 N] 2 -MnCl 4 from 400 down to 20 K (Kö ksal et al, 1999). The EPR spectra of another hybrid, [(C 2 H 5 ) 4 N] 2 MnCl 4 , also consist of a broadened line with the isotropic g-value of 2.001 (3) in the temperature range 170-300 K (Ostrowski & Ciżman, 2008).…”