Magnetic Studies of Redox‐Active Tetrathiafulvalene‐Based Complexes: Dysprosium vs. Ytterbium Analogues

Abstract

The two mononuclear complexes [Ln(tta)3(L)]·C6H14 {Ln = DyIII and YbIII} (tta– = 2‐thenoyltrifluoroacetonate, L = 2‐{1‐methylpyridyl‐4,5‐[4,5‐bis(propylthio)tetrathiafulvalenyl]‐1H‐benzimidazol‐2‐yl}pyridine) are isostructural. The lanthanide ions adopt a distorted‐square‐antiprism coordination polyhedron (D4d symmetry). The DyIII compound behaves like a single‐molecule magnet (SMM), whereas no out‐of‐phase component of the magnetic susceptibility is measured for YbIII. The crystal‐field splitting of the 2F7/2 and 6H15/2 ground multiplets of YbIII and DyIII, respectively, were determined by means of ab initio calculations and confirmed by the emission energy lines of the 2F5/2→2F7/2 luminescence spectrum in the case of YbIII. The nature of the MJ ground states indicates that YbIII is not an Ising system, whereas DyIII is. The experimental and calculated anisotropy axes for DyIII lie along the most negatively charged direction, whereas those for YbIII lie almost perpendicularly. Finally, the gz values corroborate the uniaxiality of the anisotropy axis for DyIII.

Slow Magnetic Relaxation in Unprecedented Mono-Dimensional Coordination Polymer of Ytterbium Involving Tetrathiafulvalene-Dicarboxylate Linker

“…Clearly, the anisotropy is more planar than axial. This is in contradiction with what has been observed in 8-coordinated Yb III complexes in which gz is much larger than the two other components [31]. This is probably due to the peculiar environment around the Yb III ion.…”

Slow Magnetic Relaxation in Chiral Helicene-Based Coordination Complex of Dysprosium

“…This is confirmed by the calculated composition of MJ = 0.94 |±15/2> + 0.06 |±11/2> for the ground doublet state of 1 (see Table S5 for the wavefunction composition). The calculated groundstate easy axis (Figure 6) for the Dy III ion is oriented perpendicular to the plane formed by the 2,2′-bipyridine moieties as expected for an oblate ion with this coordination sphere [31,36]. Even if the uniaxiality of the anisotropy is not strictly associated to slow relaxation of the magnetization [46], in most of the cases reported in the literature for Dy III this assumption is valid.…”

“…This is confirmed by the calculated composition of M J = 0.94 |±15/2> + 0.06 |±11/2> for the ground doublet state of 1 (see Table S5 for the wavefunction composition). The calculated ground-state easy axis (Figure 6) for the Dy III ion is oriented perpendicular to the plane formed by the 2,2 -bipyridine moieties as expected for an oblate ion with this coordination sphere [31,36]. …”

“…Indeed, it is well known that the swapping of these two ligands in such specific N 2 O 6 environment enhances the magnetic properties [36][37][38], even if in other coordination environments the opposite effect has been recently observed [39]. Therefore, we report the synthesis, the single crystal X-ray structural analysis and the magnetic characterization along with extensive ab initio calculations of the novel compound [Dy(L)(tta) 3 ] (1).…”

Luminescence and Single‐Molecule‐Magnet Behaviour in Lanthanide Coordination Complexes Involving Benzothiazole‐Based Tetrathiafulvalene Ligands

“…The rationalization of the spectra through time-dependent DFT (TD-DFT) calculations was performed through a computational strategy that has already been used successfully for TTF-based systems (see Computational Details; Figure 7b and d). [46,47] The Figure 8. The experimental absorption spectrum of L 1 was decomposed into six bands ( Figure 7a and Table 2).…”