Six-Coordinate Ln(III) Complexes with Various Coordination Geometries Showing Distinct Magnetic Properties

Abstract

Abstract:The syntheses, structural characterization, and magnetic properties of three lanthanide complexes with formulas [Ln(L 1 ) 3 ] (Ln = Dy (1Dy); Er (1Er)); and [Dy(L 2 ) 2 ] (2Dy) were reported. Complexes 1Dy and 1Er are isostructural with the metal ion in distorted trigonal-prismatic coordination geometry, but exhibit distinct magnetic properties due to the different shapes of electron density for Dy III (oblate) and Er III (prolate) ions. Complex 1Dy shows obvious SMM behavior under a zero direct current (dc) field with an effective energy barrier of 31.4 K, while complex 1Er only features SMM behavior under a 400 Oe external field with an effective energy barrier of 23.96 K. In stark contrast, complex 2Dy with the octahedral geometry only exhibits the frequency dependence of alternating current (ac) susceptibility signals without χ peaks under a zero dc field.

Synthesis, structure and magnetic properties of a series of Ln(iii) complexes with radical-anionic iminopyridine ligands: effect of lanthanide ions on the slow relaxation of the magnetization

“…[27][28] However, the presented systems exhibit a crystalloprahically imposed trigonal symmetry which should provide mixed m J states. Although, zero-field slow relaxation in six-coordinate lanthanide complexes is rather scarce, [45][46][47] complex 2 is the first example of a zero-field undiluted SMM with such imposed symmetry. This suggests that despite being weak, the exchange interactions may affect the relaxation.…”

Mononuclear Lanthanide(III)-Salicylideneaniline Complexes: Synthetic, Structural, Spectroscopic, and Magnetic Studies

“…Such a difference is also clear for the two Tb(III) complexes 6_Tb and 17_Tb. Complex 6_Tb has no magnetic response at all while 17_Tb shows χ" M dependence upon T. For a given Ln III center, the different magnetic response between the two complexes (7_Dy and 18_Dy and 6_Tb and 17_Tb) is a consequence of the different crystal fields around the metal ion in the two families [5,6,10,[15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33]. The different crystal fields arise mainly from the (i) different coordination geometries around the Ln III centers (tricapped trigonal prismatic in 6_Tb and 7_Dy vs. capped square anti-prismatic in 17_Tb and 18_Dy), (ii) different coordinated solvent molecules (H 2 O in 6_Tb and 7_Dy vs. MeOH in 17_Tb and 18_Dy), and (iii) the "cis" disposition of the salanH ligands in 6_Tb and 7_Dy as opposed to the "trans" disposition of the ligands in 17_Tb and 18_Dy (vide supra).…”

“…Currently trivalent lanthanides, Ln(III), have entered the area in a dynamic way [5][6][7][8][9][10][11][12][13][14] by virtue of their large magnetic moments and single-ion anisotropies. Mononuclear Ln(III) complexes are central "players" in this "game" because they represent one of the smallest, magnetically bi-stable units and can, thus, be considered as ideal candidates for high-density storage or quantum computing [5,6,10,[15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33]. Mononuclear Ln(III) Single-Molecule Magnets (SMMs), which are often called Single-Ion Magnets (SIMs), have been reported with a blocking temperature (~60 K) approaching that of the liquid nitrogen [34][35][36].…”

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.…”