Multifaceted magnetization dynamics in the mononuclear complex [Re^IVCl₄(CN)₂]²⁻

Abstract

The mononuclear complex (BuN)[ReCl(CN)]·2DMA (DMA = N,N-dimethylacetamide) displays intricate magnetization dynamics, implying Orbach, direct, and Raman-type relaxation processes. The Orbach relaxation process is characterized by an energy barrier of 39 K (27 cm) that is discussed based on high-field electron paramagnetic resonance (EPR), inelastic neutron scattering and frequency-domain THz EPR investigations.

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

“…Besides, the energy barrier value of 2 remains practically unaffected with increasing the dc applied magnetic field. The τ o parameter for 1 and 2 shows values that are in agreement with those that were reported for similar Re IV complexes displaying SIM behaviour [20][21][22][23].…”

“…Indeed, the effective energy barrier value obtained at the optimal dc field (H dc = 5000 G) for 1 [43.3 [21,22]. The computed values of τ o and τ QTM for 1 agree with those that were reported for other 5d-SIMs [20][21][22][23]. On the other hand, the n values for 1 lie between 4.3 and 5.5 and fall into the range typical of metal ions with relaxation through optical and acoustic Raman-like process (n being equal to 9 for the Raman relaxation of Kramer ions) [12].…”

“…The frequency-dependent ac magnetic susceptibility data of compounds 1 and 2 were modelled to give the Cole-Cole plots that are shown in Figure 6. The obtained values for the α parameter are in the ranges of 0.09-0.17 (1) and 0.06-0.11 (2), with these values suggesting a narrow distribution of the relaxation times for these mononuclear Re IV complexes [20][21][22][23][24][25]. The frequency-dependent ac magnetic susceptibility data of compounds 1 and 2 were modelled to give the Cole-Cole plots that are shown in Figure 6.…”

“…Indeed, the first SIMs based on a 5d metal ion, namely, the (NBu 4 ) 2 [ReX 4 (ox)] systems (X = Cl and Br; ox = oxalate anion), were published by some of us in 2013 [20]. Just one year later, Pedersen et al reported the research work that deals with the study of the (PPh 4 ) 2 [ ]•2DMA (DMA = N,N-dimethylacetamide) compound, that as the previously reported 5d-SIMs display field-induced slow magnetic relaxation, were also studied and published [22,23]. These last systems complete the short list of SIMs that are based on the highly anisotropic Re IV metal ion.…”

Enhancement of Intermolecular Magnetic Exchange through Halogen···Halogen Interactions in Bisadeninium Rhenium(IV) Salts

“…Anionic halorhenate(IV) salts are very appealing because of their unique magnetic properties, which include both slow relaxation and quantum tunneling of the magnetization and long-range magnetic order originating from single-ion or cooperative magnetic behaviours, respectively. [27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46] In particular, the simple hexahalorhenate(IV) salts [Re IV X6] 2-(X = F, Cl, Br, and I) of paramagnetic and diamagnetic cations generally show significant short-range intermolecular ferro-or antiferromagnetic interactions, which are mainly transmitted through relatively short intermolecular Re-X•••X-Re contacts, occasionally leading to collective magnetic phenomena such as ferromagnetism and spin canting (weak ferromagnetism). [47][48][49][50][51][52][53][54][55][56][57][58][59] Herein we report the synthesis and magneto-structural characterization of two novel Re IV compounds of general formula [H2ade]2[Re IV X6]X2•4H2O [H2ade 2+ = 9H-adenine-1,7-diium; X = Cl (1) and Br (2)].…”