Pr Compounds Research Articles

Modulation of Proinflammatory Cytokines by Parmotrema reticulatum Derived Dioxepine Derivative and Benzoic Methyl Ester in Adjuvant-Induced Arthritis.

The present investigation aims to study the therapeutic effect and to identify the lead molecules from lichen Parmotrema reticulatum (Pr) that can solve the complications associated with arthritis. Purification of Pr extract led to isolation of two lead molecules i.e. Compound A (a Dioxepine derivative) as 3-Hydroxy-9-hydroxymethyl-1,8-dimethyl-11-oxo-11H-dibenzo[b,e][1,4]dioxepine-4,7 dicarboxylic acid 7-methyl ester with molecular formula C19H16O9; molecular weight 388.34. Compound B as 3-Hydroxy-5-methoxy-4-methyl-benzoic acid (a Benzoic methyl ester) with molecular formula C9H10O4; molecular weight 182.2. In-silico investigation specific for inflammation revealed good binding affinity of both the compounds with the targeted proteins. Further continuous administration of Pr and novel compound A & B to CFA (Freund's complete adjuvant) induced arthritis rat revealed reduction in arthritis complication possibly by inhibiting the formation of edema. The variations in relative body weight along with paw swelling and arthritic scores were identified. Inhibition of expressions of RA markers like RF, CRP, TNF-𝛼, IL-1𝛽, IL-6, ALP, AST, ALT and LDH were observed there by inhibiting inflammation of synovial cavity and cartilage damage effectively. Hence from our results it is evident that Pr, Compound A & B has down regulated the inflammatory cytokines and can be a potential candidate to treat arthritis.

Low-Basicity 5-HT6 Receptor Ligands from the Group of Cyclic Arylguanidine Derivatives and Their Antiproliferative Activity Evaluation

The serotonin 5-HT6 receptor (5-HT6R), expressed almost exclusively in the brain, affects the Cdk5 signaling as well as the mTOR pathway. Due to the association of 5-HT6R signaling with pathways involved in cancer progression, we decided to check the usefulness of 5-HT6R ligands in the treatment of CNS tumors. For this purpose, a new group of low-base 5-HT6R ligands was developed, belonging to arylsulfonamide derivatives of cyclic arylguanidines. The selected group of molecules was also tested for their antiproliferative activity on astrocytoma (1321N1) and glioblastoma (U87MG, LN-229, U-251) cell lines. Some of the molecules were subjected to ADMET tests in vitro, including lipophilicity, drug binding to plasma proteins, affinity for phospholipids, drug–drug interaction (DDI), the penetration of the membrane (PAMPA), metabolic stability, and hepatotoxicity as well as in vivo cardiotoxicity in the Danio Rerio model. Two antagonists with an affinity constant Ki < 50 nM (PR 68 Ki = 37 nM) were selected. These compounds were characterized by very high selectivity. An analysis of pharmacokinetic parameters for the lead compound PR 68 confirmed favorable properties for administration, including passive diffusion and acceptable metabolic stability (metabolized in 49%, MLMs). The compound did not exhibit the potential for drug–drug interactions.

Oxygen Plasma‐Induced Modification of Structural and Electrical Properties of Pr0.5Sr0.5MnO3 Manganites

Herein, the impact of exposing the perovskite compound Pr0.5Sr0.5MnO3 to oxygen plasma is explored by comparing the structural and transport properties of the exposed samples to those of the unexposed ones. The Pr is oxidized to PrO2 in the investigated samples due to plasma exposure. The alterations in the transport properties can be linked to the changes in MnOMn bond angle and MnO bond length due to plasma exposure, as indicated by X‐ray diffraction analysis. Additionally, exposure to oxygen plasma increases the conductivity by incorporating oxygen into the exposed samples, making them oxygen‐rich. Detailed analysis of the resistivity and thermoelectric power data indicates that small polarons are responsible for conduction at high temperatures, while at low temperatures, variable range polarons take over. The negative value of the thermopower at all temperatures proclaims that the electrons behave as the dominant charge carriers.

Synthesis, spectroscopic properties, crystal structure and Hirshfeld surface analysis of Pr(III), Sm(III), Gd(III), Dy(III), and Ho(III) coordination compounds with Schiff base ligand derived from 4-aminoantipyrine

Under reflux condition five new lanthanide coordination compounds, [Pr(L)2(NO3)3(CH3OH)] (1), [Sm(L)2(NO3)3(CH3OH)] (2), [Gd(L)2(NO3)3(CH3OH)] (3), [Dy(L)2(NO3)3(CH3OH)] (4) and [Ho(L)2(NO3)3(CH3OH)] (5), were synthesized in methanol where L is the Schiff base ligand prepared from the reaction of 4-aminoantipyrine and 5-bromosalicylaldehyde. Elemental analysis, FT-IR, UV/Vis and photoluminescence spectroscopic methods and single crystal X-ray analysis were used to investigate the crystal structure and properties of the synthesized compounds. Using X-ray analysis, it was found that all crystals are isomorphous and the Ln ion (Ln = Pr, Sm, Gd, Dy and Ho) in all of the synthesized compounds is nine-coordinated and the geometry around them is slightly distorted tricapped trigonal prism. Six oxygen atoms are coordinated to the central lanthanide atom by three nitrate groups, one oxygen atom from the methanol group and two oxygen atoms of the Schiff base ligand (L) which create the LnO9 coordination environment. Intermolecular interactions and the distribution of these interactions in all of these crystals were calculated by Hirshfeld surface analysis using Crystal Explorer 17.5 software. The emission spectrum of these compounds was recorded and the obtained results showed that the intensity of peaks has differences and the emission spectrum of the complexes changes by changing the lanthanide ions.

Unusual superconductivity in crystallographically disordered RT2−xSn2 compounds

The discovery of new superconducting materials represents a complementary and crucial tile to shed light on the mechanism controlling the phenomenon of superconductivity. During the search for new superconducting materials, we discovered a new series of intermetallic compounds with the general composition RZn2−xSn2 (R = La, Ce, Pr, Nd). Their formation and crystal structure have been investigated. The Zn content decreases along the series from ≈ 1.50 in LaZn1.50(1)Sn1.98(2) to ≈ 1.32 in NdZn1.321(8)Sn2.01(2), due to the partial occupation of one of the two Zn sites [the Zn1 (2c) site, which from ≈ 50% in the La compound drops to ≈ 42%, ≈ 37% and ≈ 32% in the Ce, Pr and Nd compounds, respectively]. Both the Zn occupation factor and unit cell volume follow the lanthanide contraction. No such compound has been observed with Sm. AC and DC magnetic susceptibility and transport measurements revealed LaZn1.5Sn2 to undergo a sharp superconducting transition at Tc = 5.5 K. In order to search for further possible superconductive homologues, the lanthanum substituted phases La(Zn,T)2–xSn2 (T = Ti, Mn, Fe, Co, Ni, Cu, Pd, Ag, Pt, Au, Cd; x ≈ 0.5) were also prepared. The crystal structure of the ternary compounds is a disordered defective derivative of the tetragonal CaBe2Ge2-type (tP10, P4/nmm), with a partially occupied Zn Wyckoff site and a disordered Sn position. Three related isostructural series, corresponding to three new prototypes, have been identified; they all contain conventional checkered pyramidal layers characteristic of the archetype. The magnetic and transport properties have been measured for some of these substituted quaternary La compounds and we found that superconductivity is preserved in them but in the orthorhombic compounds or when T was a magnetic transition metal (e.g., Ni or Mn). A slight decrease in Tc down to about 4.0 K was detected as a result of the Zn by T atomic substitution.

First-order phase transition in perovskites Pr0.67Sr0.33MnO3 – magneto-caloric properties – effect of multi-spin interaction

We show by extensive Monte Carlo simulations that we need a multi-spin interaction in addition to pairwise interactions in order to reproduce the temperature dependence of the experimental magnetization observed in the perovskite compound Pr0.67Sr0.33MnO3. The multi-spin interaction is introduced in the Hamiltonian as follows: each spin interacts simultaneously with its four nearest-neighbors. It does not have the reversal invariance as in a pairwise interaction where reversing the directions of two spins leaves the interaction energy invariant. As a consequence, it competes with the pairwise interactions between magnetic ions. The multi-spin interaction allows the sample magnetization M to increase, to decrease or to have a plateau with increasing T. In this paper we show that M increases with increasing T before making a vertical fall at the transition temperature TC, in contrast to the usual decrease of M with increasing T in most of magnetic systems. This result is in an excellent agreement with the experimental data observed in Pr0.67Sr0.33MnO3. Furthermore, we show by the energy histogram taken at TC that the transition is clearly of first order. We also calculate the magnetic entropy change |ΔSm| and the Relative Cooling Power (RCP) by using the set of curves of M obtained under an applied magnetic field H varying from 0 to 5 T across the transition temperature region. We obtain a good agreement with experiments on |ΔSm| and the values of RCP. This perovskite compound has a good potential in refrigeration application due to its high RCP.

Effect of Pr(NO3)3 doping on the characteristics of TC4 micro-arc oxidation coatings

Micro-arc oxidation coatings were prepared on the surface of TC4 by adding different contents of rare-earth compound Pr(NO3)3 to the aluminate and phosphate-based electrolyte. The results showed that the change in oxidation voltage increased at first and then decreased with the raised of Pr(NO3)3 addition. At 0.05 g L−1, the oxidation voltage reached the maximum, the number of discharge micropores decreased, while the size increased, the thickness and hardness of the coatings reached the peak values. The coatings mainly included Al2TiO5, anatase, γ-Al2O3 and a little of Pr2O3. Pr(NO3)3-doped coatings showed excellent corrosion resistance in 3.5% NaCl electrochemical workstation and oilfield simulation fluid containing 5% NaCl, and the corrosion resistance of the coatings reached the best at 0.05 g L−1.

Extended investigation of the conductive characteristics of monoclinic tungstates with a Bi3.24Ln2W0.76O10.14 (Ln = La, Pr or Nd) composition.

δ-Bi2O3-based materials have long been a focus of interest as potential solid oxide fuel cell materials due to their high electrical conductivity. Here, extensive studies of thermal stability, polymorphism and conductivity have been carried out for the first time on Bi3.24Ln2W0.76O10.14 (Ln = La, Pr or Nd) compounds in the ternary Bi2O3-Ln2O3-WO3 system, mentioned more than 20 years ago by Watanabe. The obtained single-phase materials were found to be sufficiently dense (more than 94%) and thermally stable (up to 900 °C). Emphasis was placed on studying the nature of the electrical transport of these phases, which was investigated through high-throughput calculations and experimental measurements. Theoretical studies included a crystal chemical evaluation of conductivity channels and migration energy, calculation of ionic conductivities using the kinetic Monte Carlo method, and determination of band gaps using a quantum-chemical approach. Experimental conductivity investigations were carried out over a wide temperature range (up to 900 °C) and at various oxygen partial pressures. For Bi3.24Ln2W0.76O10.14, the anionic type of conductivity is predominant with a share of the electronic component. The total conductivity values reached about 10-2 S cm-1 at 900 °C for all samples, confirmed by both calculation and measurement. These theoretical and experimental findings enhance the understanding of the nature and mechanism of Watanabe's phase conductivity.

A comparative ab initio study on mechanical and thermal properties of rare-earth scandate LnScO3 (Ln = La, Pr, Nd, Sm, Eu and Tb) compounds

To comparatively examine the mechanical and thermal properties of rare-earth scandate LnScO3 (Ln = La, Pr, Nd, Sm, Eu and Tb) compounds, ab initio calculation based on density functional theory was used within the framework of the generalized gradient approximation. The elastic moduli, Pugh’s criterion, Poisson’s ratio, Vickers hardness, linear compressibility, Debye temperature, Grüneisen parameter, elastic wave velocities, minimum thermal conductivities of LnScO3 were successfully obtained from independent single crystal elastic coefficients. The computed elastic constants indicate that these compounds have mechanical stability. The ductile and brittle properties of LnScO3 compounds were investigated using the B H /G H , Poisson’s ratio and Cauchy pressure. The mechanical anisotropic properties of LnScO3 compounds were discussed using universal anisotropic index, shear anisotropy factors, percentage shear (compressible) anisotropy index. Minimum thermal conductivities of LnScO3 were determined using Cahill’s and Clark’s model. Except for the elastic coefficients of NdScO3, SmScO3 and TbScO3 compounds, many physical properties of LnScO3 compounds were calculated for the first time in this study. We compared our calculation results with experimental and other theoretical data available in the literature.

NaLn(IO3)4 Iodates (Ln = Pr, Tb): New Representatives of Nonlinear Optical Crystals with the NaY(IO3)4 Structure

Interaction of rare-earth oxides (Pr, Tb, Er) with periodic acid or sodium iodate under hydrothermal conditions in the presence of Na2HPO4⋅12H2O leads to formation of complex NaLn(IO3)4 iodates. The compounds of Pr and Tb are reported for the first time. Single-crystal studies reveal that they are isostructural to the previously reported analogs of other rare-earths and adopt the non-centrosymmetric space group Сс. Polycrystalline samples generate a strong SHG signal above that of the potassium dihydrogen phosphate reference standard. They also exhibit wide optical transparency areas and high thermal stability.

Synthesis, Crystal Structure, and Electrical and Magnetic Characterizations of the Monoclinic Compounds Ln3Mo4+xSi1–xO14 (Ln = La, Ce, Pr, and Nd; x = 0 and 0.35) Containing Mo3 Clusters and Mo2 Dimers

Powder samples of the new monoclinic compounds Ln3Mo4SiO14 (Ln = La, Ce, Pr, and Nd) and single crystals of Pr3Mo4.35Si0.65O14 were obtained by the solid-state reaction. The crystal structure of Pr3Mo4.35Si0.65O14 was determined by single-crystal X-ray diffraction. Pr3Mo4.35Si0.65O14 crystallizes in the monoclinic space group P21/n with unit-cell parameters a = 5.6361 (2) Å, b = 17.5814 (8) Å, c = 10.9883 (4) Å, and Z = 4. Full-matrix least-squares refinement on F2 using 7544 independent reflections for 203 refinable parameters results in R1 = 0.0359 and wR2 = 0.0831. The structure contains chains of Mo3O13 clusters and chains of edge-sharing MoO6 octahedra with alternately short (2.508 Å) and long (3.161 Å) Mo-Mo distances running parallel to the a axis that are separated by 8- or 10-coordinate Pr-O polyhedra. Magnetic susceptibility measurements on the Ln3Mo4SiO14 (Ln = La, Ce, Pr, and Nd) are in agreement with a trivalent state of the rare earths for the Ce, Pr, and Nd compounds, while that on the lanthanum compound confirms the presence of one unpaired electron per Mo3 as expected. Resistivity measurements on a single crystal show that Pr3Mo4.35Si0.65O14 is a small band gap semi-conductor.

Blue-Emitting Ligand-Mediated Assembly of Rare-Earth MOFs toward White-Light Emission, Sensing, Magnetic, and Catalytic Studies.

New lanthanide carboxylate compounds with two- (2D) and three-dimensional (3D) structures have been prepared by employing 2,5-bis(prop-2-yn-1-yloxy)terephthalic acid (2,5-BPTA) as an organic linker. The compounds, [Ln(C14H8O6)(C7O3H4)·2H2O]·4(H2O), Ln = Y, Pr, Nd, Sm, Eu, Gd, Tb, Dy and [Ln(C7O3H4)3·(C3H7ON)·(H2O)]·2(H2O)(C3H7NO), Ln = La, Ce, Pr, have two- and three-dimensional structures, respectively. In all compounds, lanthanide ions are connected together, forming a dimer, which is connected by the 2,5-BPTA ligand. In the two-dimensional structure, there are two 2,5-BPTA moieties present, and in the three-dimensional structure, there are three 2,5-BPTA moieties present. The lanthanide centers are nine-coordinated, the 2D structure has a tricapped trigonal prismatic arrangement, and the 3D structure has a monocapped distorted square antiprismatic arrangement. The Pr compound forms in both 2D and 3D structures, whose formation depends on the time of the reaction (2 days─2D and 5-6 days─3D). The ligand emits in the blue region, and using the characteristic emission of Eu3+ (red) and Tb3+ (green) ions, we achieve white light emission in the (Y0.96Tb0.02Eu0.02) compound. The overall quantum yield for the white light emission is 28%. The strong green luminescence of the Tb3+-containing compound was employed to selectively sense the Cr3+ and Fe3+ ions in aqueous solution with limits of detection (LODs) at 0.41 and 8.6 ppm, respectively. The Tb compound was found to be a good heterogeneous catalyst for the Ullman-type O-arylation reaction between phenol and bromoarene with yields of 95%. Magnetic studies on the Gd-, Tb-, and Dy-containing compounds showed weak exchange interactions within the dimeric Ln2 units. The present work demonstrates the many utilities of the rare-earth-containing MOFs, especially toward white-light emission, metal-ion sensing, and heterogeneous catalysis.

Exploring the structural stability and optical properties of rare-earth doped K3LuSi2O7 phosphor from first-principles calculations

The newly developed rare-earth doped K3LuSi2O7 phosphor have promising applications in phosphor-converted light-emitting diodes that achieve broadband high-efficiency near-infrared emission. However, the further development of such luminescent materials is hindered by the difficulty in establishing the quantitative relationship between the microstructure and optical properties from experiments. This work performed first-principles calculations to study the optical properties of K3LuSi2O7:x (x = Eu, Nd, Pr) compounds in relation to the atomic structure and external pressure, within the framework of hybrid functional. It is found that the direct band gap of K3LuSi2O7 can be dramatically narrowed by doping rare-earth elements into K sites and applying external pressure, with distinct microscopic mechanisms. We predicted the energy-dependent absorption spectra of these compounds by assuming that the probabilities of different atomic configurations appearing follows the Boltzmann distribution when the real material is in a thermodynamically stable state. The results demonstrate that the absorption spectrum of K3LuSi2O7:x (x = Eu, Nd, Pr) can be effectively tuned in the visible and near-infrared regions, making it a phosphor with specific luminescence characteristics.

Functional integral approach for temperature dependence of the magnetic hyperfine field at a Cd site in RCd (R = Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho and Er)

A theoretical study of the local moment formation and of the magnetic hyperfine field at a non-magnetic s-p site, namely Cd, embedded in RCd (R = Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho and Er) compounds is reported. The functional integral approach in the static approximation is adopted to calculate the temperature dependence of the local magnetic moments and hyperfine magnetic interactions, which is an extension of conventional mean field approach. Our calculations are performed in the temperature range from T=0K up to the critical temperatures TC of each compound, when they become paramagnetic. The local magnetic moments at a Cd, as a function of the temperature, were calculated from the perturbed densities of states. The results of our self-consistent calculations for the magnetic hyperfine field at the impurity site are in very good agreement with recent experimental reports. Furthermore, at T=0 K our results are compared with those obtained from ab initio calculations.

Emergent flat-band physics in d9−δ multilayer nickelates

Recent experiments showed that the reduced multilayer rare-earth (RE) nickel oxides of form $\mathrm{R}{\mathrm{E}}_{p+1}{\mathrm{Ni}}_{p}{\mathrm{O}}_{2p+2}$ may belong to the novel family of superconducting lanthanide nickelates. Here, the correlated electronic structure of ${\mathrm{Pr}}_{4}{\mathrm{Ni}}_{3}{\mathrm{O}}_{8}$ and ${\mathrm{Nd}}_{6}{\mathrm{Ni}}_{5}{\mathrm{O}}_{12}$ is studied by means of an advanced realistic many-body framework. It is revealed that the low-energy physics of both systems is dominated by an interplay of Ni-${d}_{{x}^{2}\ensuremath{-}{y}^{2}}$ and Ni-${d}_{{z}^{2}}$ degrees of freedom. While the Ni-${d}_{{x}^{2}\ensuremath{-}{y}^{2}}$ orbitals are always highly correlated near a (orbital-selective) Mott-insulating regime, the Ni-${d}_{{z}^{2}}$ orbitals give rise to intriguing nondispersive features. At low temperature, the Pr compound still displays quasiparticle-like Ni-${d}_{{x}^{2}\ensuremath{-}{y}^{2}}$-derived states at the Fermi level, but the interacting fermiology of the Nd compound is outshined by an emergent Ni-${d}_{{z}^{2}}$-controlling flat band. These findings translate well to the previous characterization of doped infinite-layer nickelates, and hence further make the case for a mechanism of unconventional superconductivity, which is distinct from the one in high-${T}_{\mathrm{c}}$ cuprates.

Studies toward the Use of Ionic Liquids and Supercritical CO2 for the Recovery and Separation of Praseodymium from Waste Streams

Waste streams from the incineration of metal-containing materials like such as computer processor boards and batteries may contain critical rare earth elements like praseodymium. Data on the solubility of Pr compounds and on their distribution coefficients in supercritical CO2/ionic liquid two-phase systems are important to determine if an ionic liquid/supercritical CO2 two-phase approach is feasible toward the recovery of a particular metal. This work provides data on the solubility of various praseodymium compounds in butyl-methyl-pyrrolidinium bis(trifluoromethylsulfonyl)imide (BMPyTf2N) ionic liquid and on the distribution coefficients of these praseodymium compounds in the supercritical CO2 phase of the two-phase BMPyTf2N ionic liquid/supercritical CO2 system, with and without a tributyl phosphate additive.

Synthesis, structure and characterization of Pr[B5O8(OH)]NO3·2H2O

A new rare earth metal borate crystalline compound Pr[B5O8(OH)]NO3·2H2O (1) containing nitrate anions was obtained using a hydrothermal method. The crystal structure was examined using single-crystal X-ray diffraction. The compound crystallises in the monoclinic system (space group P21/n) with a = 6.4619(5) Å, b = 15.4518(13) Å, c = 10.5754(8) Å, β = 90.357(2)° and V = 1055.91(14) Å3. The basic building block of the compound was a [B5O10(OH)]6− polyanion cluster, which forms a two-dimensional B–O layered structure; The Pr3+ ions fill the windows of the B–O layers, whereas the nitrates and water molecules occupy the gaps between the B–O layers. The crystal structure was further characterised using powder diffraction, infrared transmission spectroscopy and thermogravimetric analysis. In addition, the solid-state fluorescence emission spectra of the crystal were measured, showing the characteristic emission peaks of Pr3+.

Near Room-Temperature Temperature Magnetocaloric Effect in Pr0.63-xHoxSr0.37MnO3 Manganites

"Near room-temperature magnetic and magnetocaloric properties of the compounds Pr0.63-xHoxSr0.37MnO3 (x=0, 0.05) were investigated. The parent compound Pr0.63Sr0.37MnO3 has a large magnetocaloric effect around its Curie temperatures of about 300 K. Partially replacing of Pr3+ ions with Ho3+ ions in Pr0.63Sr0.37MnO3 gives rise to disorder which leads to the decrease of the Curie temperature without a significant reduction of the magnetocaloric effect. The samples were prepared by solid state reaction and were found to be single phase by x-ray diffraction. The magnetic measurements reveal paramagnetic to ferromagnetic second order phase transitions. For the sample with x = 0, the magnetic entropy change |ΔSM| was in the range from 1.91 J/kg٠K (RCP = 42 J/kg) forμ0 ΔH = 1 T to 4.86 J/kg٠K (RCP = 184 J/kg) for μ0 ΔH = 4 T. For the sample with x = 0.05, the magnetic entropy change |ΔSM| was in the range from 1.61 J/kg٠K (RCP = 57.9 J/kg) forμ0 ΔH = 1 T to 4.38 J/kg٠K (RCP = 236 J/kg) for μ0 ΔH = 4 T and Tc = 216 K. These values recommend these materials to be potential candidates to be used in near room-temperature refrigeration applications. Keywords: Perovskite manganites, phase transition, magnetocaloric effect. "

Evolution of non-Kramers doublets in magnetic field in PrNi2Cd20 and PrPd2Cd20

Praseodymium-based 1-2-20 cage compounds Pr$T_2X_{20}$ ($T$ is generally Ti, V, Nb, Ru, Rh, Ir; and $X$ is either Al, Zn or Cd) provide yet another platform to study non-trivial electronic states of matter ranging from topological and magnetic orders to unconventional multipolar orders and superconductivity. In this paper, we report measurements of the electronic heat capacity in two Pr-based 1-2-20 materials: PrNi$_2$Cd$_{20}$ and PrPd$_2$Cd$_{20}$. We find that the lowest energy multiplet of the Pr $4f^2$ valence configuration is a $\Gamma_3$ non-Kramers doublet and the first excited triplet is assumed to be a magnetic $\Gamma_5$. By analyzing the dependence of the energy splitting between the ground and first excited singlet states on external magnetic field, we found that the maximum in the heat capacity corresponding to the Schottky anomaly in PrPd$_2$Cd$_{20}$, unlike PrNi$_2$Cd$_{20}$, shows pronounced linear dependence on external magnetic field at higher field values. This effect is associated with the exchange interactions between the field-induced magnetic dipole moments.

Rare-Earth-Silyl ate-Complexes Opening a Door to Selective Manipulations.

The reactions of a number of rare-earth (RE) trichlorides and an oligosilanylene diide containing a siloxane unit in the backbone in DME are described. The formed products of the type [(DME)4·K][(DME)·RE(Cl)2{Si(SiMe3)2SiMe2}2O] (RE = Y, La, Ce, Pr, Sm, Tb, Dy, and Er) are disilylated dichloro metalate complexes and include the first examples of Si–La and Si–Pr compounds as well as the first structurally characterized example of a Si–Dy complex. A most intriguing aspect of the synthesis of these complexes is that they offer entry into a systematic study of the still largely unexplored field of silyl RE complexes by the possibility of ligand exchange reactions under preservation of the Si–RE interaction. This was demonstrated by the conversion of [(DME)4·K][(DME)·RE(Cl)2{Si(SiMe3)2SiMe2}2O] to [(DME)4·K][Cp2Y{Si(SiMe3)2SiMe2}2O].