Field-Induced Single Molecule Magnets of Phosphine- and Arsine-Oxides

Abstract

The coordination chemistry of dysprosium and terbium toward phosphine and arsine oxides was further explored. Thus, the new nitrate [M(NO3)3(Ph3PO)3] (M = Tb, 1; Dy, 2), [Dy(NO3)3(EtOH)(Ph3XO)2] (X = P, 3; As, 4), chloride [DyCl2(Ph3AsO)4]Cl (5), triflate [Dy(OTf)2(MePh2PO)4]OTf (6; OTf = triflate) and hexafluoroacetylacetonate [M(hfa)3(Ph3PO)2] (hfa = hexafluoroacetylacetonate; M = Tb, 7; Dy, 8) complexes were isolated and fully characterized. The crystal structures of 1·CH3CN, 2·CH3CN, 4, 5·2.75EtOH·1.25H2O, 6, 7, and 8 show MO9 cores in 1, 2, and 4, with highly distorted geometry, between spherical capped square antiprism and muffin-like, hexacoordinated environments for the dysprosium ions in 5 and 6, with octahedral geometry, and octa-coordination for the lanthanoid metals in 7 and 8, with geometry closer to square antiprism. Comparison of the magnetic behavior of all the complexes allows analyzing which metal ion (Tb or Dy), phosphine or arsine oxide, or anionic ligand favor more the slow relaxation of the magnetization. Alternating current magnetic measurements show that only 2, 4, and 8 present slow relaxation of the magnetization in the presence of an external magnetic field, 8 being the complex with the highest Ueff (44.85 K) of those described herein.

Improving the luminescent properties of a dysprosium complex with in the presence of Zn^II: an emissive Zn₂Dy compound

“…Computations with the SHAPE software [9] indicate that the geometry about the Dy 3+ ion is now closest to spherical capped square antiprism (Figure 4), but with a significant distortion towards muffin-like. Once again, all the bond distances and bond angles in Zn2Dy (Table 2) are in the usual range [10][11]. …”

“…1635 and 1300 cm -1 are also present, indicating the existence in both compounds of imine [6,8] moieties and nitrate groups [8], respectively. In this structure, all the distances and angles about the metal ion are within their usual range and do not merit further consideration [10][11].…”

Field-Induced Single-Molecule Magnets of Dysprosium Involving Quinone Derivatives

“…The compounds 1 and 2 displayed a magnetic relaxation mainly through a pure Raman process (Figure 4, Figure 6 and Figure S9), which could be justified by the applied magnetic field (cancelling of the QTM), the moderate value of the field (the direct process is not the fastest magnetic relaxation process) and the low temperature range at which the relaxation times are extracted (below 10 K), leading to a negligible Orbach contribution. Recently, several Dy III -based SMMs displaying pure Raman magnetic relaxation under moderate applied field in the low temperature range have been reported [43][44][45][46][47][48][49]. For some of the reported example in Table 1, an Orbach process can be involved in the magnetic relaxation in the high temperature range, in which an out-of-phase contribution of the magnetic susceptibility was measured.…”

Octahedral Hexachloro Environment of Dy3+ with Slow Magnetic Relaxation and Luminescent Properties

“…In order to have further insight in the magnetic behaviour, we have examined the structures of compounds showing Dy 3 + ions in different octahedral environments (Figure 7 and Table S6) and some characteristic values describing their magnetic behaviours are given in Table 1. [35][36][37][38][39][40][41][42][43] Since the local geometry influences the magnetic properties, we have limited this research to compounds containing Dy 3 + ions surrounded by six ligands in an octahedral geometry (see CShM values in Table 1). As one can observe, the majority of these compounds showing SIM properties tends to exhibit the shorter distances along the axial direction and angle values comprised between 170°and 180°.…”

“…Regarding SIMs, only few examples of mononuclear compounds containing lanthanide ions in octahedral environment were reported. [35][36][37][38][39][40][41][42][43][44][45] Possibility to achieve unusual coordination environments for Ln 3 + ions was observed with the use of Ionic Liquids (ILs). [46] In particular, the formation and stabilization of octahedral entities of formula [LnCl 6 ] 3À in the solid state was described using phosphonium or alkyl imidazolium ILs with Ln chloride salts.…”