Hexakis(dimethylformamide)iron(II) complex cation in hexahalorhenate(IV)-based salts: synthesis, X-ray structure and magnetic properties

Abstract

Figure S1. PXRD plots for samples of compounds 1 (blue) and 2 (red).

Field-Induced Single-Ion Magnet Phenomenon in Hexabromo- and Hexaiodorhenate(IV) Complexes

“…A field dependence of the molar magnetisation (M) plot for 1 and 2 at 2.0 K is given in the respective insets of Figure 3a(1),b(2). In all the cases, the M values display a continuous increase with the applied magnetic field, the higher M values being 1.57 (1) and 1.53 µB (2) at 5.0 T, which are in agreement with those of similar mononuclear Re IV complexes that were reported in the literature [18,[27][28][29][30][31][32][33][34][35][36][37][38][39][40][41]. Given that no significant intermolecular interactions are observed in the crystal structures of 1 and 2, as indicated in the structure description, the shortest intermolecular Re-X•••X-Re distances are covering the range of 5.93-6.52 Å, we have performed the treatment of the experimental data of the χMT versus T plots through the anisotropic Hamiltonian of Equation (1) (where Ŝz is the easy-axis spin operator, H is the applied field, β is the Bohr magneton, g is the Landé factor, and D is the ZFS for the Re IV ion).…”

“…The solid red line, indicating the fit in Figure 3a(1),b(2), matches quite well the experimental curves in both cases. The g and D values that are computed for 1 and 2 are in agreement with those calculated for previously reported mononuclear Re IV complexes [18,[27][28][29][30][31][32][33][34][35][36][37][38][39][40][41]. The |D| value that is obtained for 2 is somewhat greater than that of the complex 1.…”

“…1.0 cm 3 mol −1 K), as previously reported [18]. The decrease of the χ M T values observed for complexes 1 and 2 is mainly due to zero-field splitting (ZFS) effects, which are very significant in Re IV -based systems [18,[27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42].…”

“…Both of the compounds exhibit a very similar behaviour that is represented in the form of χ M T versus T plots (χ M being the molar magnetic susceptibility per Re IV ion) for 1 and 2 in Figure 3. At room temperature, the χ M T values are approximately 1.58 (1) and 1.54 cm 3 mol −1 K (2), which fall into the range that was reported for systems containing a magnetically isolated Re IV (S = 3/2 with g = 1.80-1.90) metal ion [18,[27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42]. Upon cooling, the χ M T values for these compounds decrease first slowly and, around 70-80 K, they decrease faster, reaching minimum values of approximately 0.95 (1) and 0.96 cm 3 mol −1 K (2) at 2.0 K. These minimum values obtained at very low temperature are close to that expected for a magnetically isolated Re IV ion (ca.…”

“…We have studied further hexahalorhenate(IV) salts of the PPh 4 + cation to develop our investigation in 5d-SIMs. Thus, by means of this bulky cation, the well-known intermolecular Re-X•••X-Re (X = halide ion) interactions, with pathways that can mediate significant magnetic exchanges between neighbouring [ReX 6 ] 2− complexes in the crystal lattice, hence annulling the SIM behaviour of such systems, are avoided [18,[27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42].…”