Magnetism, electronic spectra, and structure of transition metal alkoxides. II. The preparation and magnetism of iron(III) alkoxides

1966 ◽  
Vol 19 (3) ◽  
pp. 363 ◽  
Author(s):  
RW Adams ◽  
RL Martin ◽  
G Winter
Keyword(s):  
Room Temperature ◽  
Benzene Solution ◽  
Magnetic Moments ◽  
Exchange Interactions ◽  
Metal Alkoxides ◽  
Antiferromagnetic Exchange ◽  
Crystal Data ◽  
Magnetic Susceptibilities ◽  
X Ray ◽  
The Core

The iron(III) alkoxides, Fe(OMe)3, Fe(OEt)3, and Fe(Obun)a have been prepared by a procedure alternative to those previously described in the literature. The trimeric nature of the three compounds in benzene is confirmed by cryoscopy, and preliminary X-ray single crystal data for the ethoxide are consistent with trimeric entities in the solid. The temperature variation of the magnetic susceptibilities for the three compounds follows the Curie-Weiss law between 90 and 300�K but with large values of θ=- 200�K. The unusually low magnetic moments vary markedly with temperature, and at room temperature remain depressed in benzene solution at peer μeff 4.4 B.M. This anomalous behaviour is ascribed to the presence of weak antiferromagnetic exchange interactions within the cluster of iron atoms which forms the core of the trimeric species Fe3(0R)9. The compounds are sensitive both to hydrolysis and to heating. Hydrolysis decreases and pyrolysis increases the magnetic susceptibility. This provides a convenient method for following the progress of both types of reaction.

The anomalous paramagnetism of iron(III) NN-dialkyldithiocarbamates

1964 ◽  
Vol 17 (3) ◽  
pp. 294 ◽  
Author(s):  
AH White ◽  
R Roper ◽  
E Kokot ◽  
H Waterman ◽  
RL Martin
Keyword(s):  
Molecular Weight ◽  
Thermal Equilibrium ◽  
Room Temperature ◽  
Chemical Nature ◽  
Magnetic Moments ◽  
Chloroform Solution ◽  
Exchange Interactions ◽  
Magnetic Behaviour ◽  
Antiferromagnetic Exchange ◽  
Molecular Type

The magnetic moments of a series of 19 NN-disubstituted dithiocarbamates of iron(III), [Fe(S2C.NR?R")3], are anomalous in that their behaviour is neither "high-" nor "low-spin". Values of μeff. at room temperature lie between 2.62 and 5.83 B.M., the datum for each compound depending on the chemical nature of the substituents R' and R". This anomalous situation persists in benzene or chloroform solution. Cryoscopic and ebullioscopic molecular weight determinations establish that all the compounds are monomeric, which excludes the possibility that the magnetic behaviour arises from the presence of antiferromagnetic exchange interactions of either the inter- or intra-molecular type. These observations strongly support the early and generally overlooked work of Cambi who in 1932 proposed a thermal equilibrium between "magnetic isomers" of spins S = � and S = 5/2 to account for the origin of the magnetic anomaly.

scholarly journals The Isomorphous Structures of Ammonium trans-Diiodobis(ethanedial-dioximato-(1–)-N,N′)cobaltate(III) and Ammonium trans-Diiodobis(ethanedial-dioximato-(1–)-N,N′)rhodate(III): Extended Metaloximate Chains with a Novel ···I–M–I···I–M–I··· Zigzagged Structure

1990 ◽  
Vol 45 (11) ◽  
pp. 1508-1512 ◽  
Author(s):  
Michel Mégnamisi-Bélombé ◽  
Bernhard Nuber
Keyword(s):  
Room Temperature ◽  
Ammonium Salts ◽  
Monoclinic Space Group ◽  
Hydroxyl Groups ◽  
Coordination Geometry ◽  
Crystal Data ◽  
X Ray Diffraction ◽  
X Ray ◽  
Anionic Complexes ◽  
Complex Anions

The ammonium salts of the complex anions trans-diiodobis(ethanedial-dioximato)-cobaltate(III), [Col2(GH)2]-, and trans-diiodobis(ethanedial-dioximato)rhodate(III), [RhI2(GH)2]- (GH- = ethanedial dioximate or glyoximate), have been synthesized and their structures determined from single crystal X-ray diffraction data at room temperature. The crystals of the two salts are monoclinic, space group C2/c. NH4[CoI2(GH)2] (I) crystallizes as dark-brown prisms with a greenish reflectance; its crystal data are: C4H10Col2N5O4, Mr = 504.90; a = 8.910(6), b = 11.700(9), c = 11.691(6) Å; β = 93.55(5)°; V = 1216.4 Å3; Z = 4; Dc = 2.78 Mg m-3. NH4[RhI2(GH)2] (II) crystallizes as yellow-brown blocks with crystal data: C4H10I2N5O4Rh, Mr = 548.88; a = 9.038(4), b = 11.949(5), c = 11.770(3) Å; β = 95.54(3)°; V = 1265.16 A3; Z = 4; Dc = 2.87 Mg m-3. The two structures were refined to a final RW = 0.045 for 1209 observed independent reflections and 95 parameters for I, and to a final RW = 0.040 for 1922 observed independent reflections and 87 parameters for II. The coordination geometry around Co or Rh in the anionic complexes is a distorted (4 + 2) octahedron of four equatorial chelating N atoms and two apical iodides. The H atoms of the hydroxyl groups are involved, as usual, in intramolecular O—H—O bridges with uniform Ο···Ο separations of 2.582 Å for I, and 2.713 Å for II. The rectilinear I—Co—I or I—Rh—I triads form “infinite” zigzag chains extending parallel to the ab plane, with a weak I—I contact of 3.988 Å for I, and 4.010 Å for II.

Rb2CaCu6(PO4)4O2, a novel oxophosphate with a shchurovskyite-type topology: synthesis, structure, magnetic properties and crystal chemistry of rubidium copper phosphates

2019 ◽  
Vol 75 (5) ◽  
pp. 903-913
Author(s):  
Sergey M. Aksenov ◽  
Elena Yu. Borovikova ◽  
Vladimir S. Mironov ◽  
Natalia A. Yamnova ◽  
Anatoly S. Volkov ◽  
...  
Keyword(s):  
Multicomponent System ◽  
Exchange Interactions ◽  
Magnetic Behavior ◽  
Molar Ratio ◽  
Monoclinic Space Group ◽  
Antiferromagnetic Exchange ◽  
X Ray ◽  
Low Dimensional ◽  
Fierce Competition ◽  
Ordered State

Single crystals of Rb2CaCu6(PO4)4O2 were synthesized by a hydrothermal method in the multicomponent system CuCl2–Ca(OH)2–RbCl–B2O3–Rb3PO4. The synthesis was carried out in the temperature range from 690 to 700 K and at the general pressure of 480–500 atm [1 atm = 101.325 kPa] from the mixture in the molar ratio 2CuO:CaO:Rb2O:B2O3:P2O5. The crystals studied by single-crystal X-ray analysis were found to be monoclinic, space group C2, a = 16.8913 (4), b = 5.6406 (1), c = 8.3591 (3) Å, β = 93.919 (3)°, V = 794.57 (4) Å3. The crystal structure of Rb2CaCu6(PO4)4O2 is similar to that of shchurovskyite and dmisokolovite and is based upon a heteropolyhedral open framework formed by polar layers of copper polyhedra linked via isolated PO4 tetrahedra. The presence of well-isolated 2D heteropolyhedral layers in the title compound suggests low-dimensional magnetic behavior which is masked, however, by the fierce competition between multiple ferromagnetic and antiferromagnetic exchange interactions. At T C = 25 K, Rb2CaCu6(PO4)4O2 reaches a magnetically ordered state with large residual magnetization.

Heterobimetallische 3d-4f-Komplexe mit Bis(1,2-dithiooxalato)nickelat(II) als planarem Brückenbaustein / Heterobimetallic 3d-4f-Complexes with Bis(1,2-dithiooxalato)nickelate(II) as Planar Bridging Block

2005 ◽  
Vol 60 (11) ◽  
pp. 1149-1157 ◽  
Author(s):  
Matthias Siebold ◽  
Alexandra Kelling ◽  
Uwe Schilde ◽  
Peter Strauch
Keyword(s):  
Room Temperature ◽  
Magnetic Moments ◽  
Lanthanide Ions ◽  
Water Molecules ◽  
Unit Cell Parameters ◽  
Ionic Radii ◽  
X Ray ◽  
Cell Parameters ◽  
Heterobimetallic Complexes ◽  
The Individual

Planar bis(1,2-dithiooxalato)nickelates(II) react in aqueous solutions of lanthanide ions to form pentanuclear, heterobimetallic complexes of the general composition [{Ln(H2O)n}2- {Ni(dto)2}3]・xH2O (Ln = Y3+, La3+, Ce3+, Pr3+, Nd3+, Sm3+, Eu3+, Gd3+, Tb3+, Dy3+, Ho3+, Er3+, Tm3+, Yb3+, Lu3+; n = 4 or 5; x = 9 - 12). With [{Nd(H2O)5}2{Ni(S2C2O2)2}3]・xH2O (x = 10 - 12) (1) and [{Er(H2O)4}2{Ni(S2C2O2)2}3]・xH2O (x = 9 - 10) (2) we were able to isolate two complexes of this series as single crystals, which were characterized by X-ray structure analysis. Depending on the individual ionic radii of the lanthanide ions, the compounds crystallize in two different crystal systems with the following unit cell parameters: 1, monoclinic in P21/c with a = 11.3987(13), b = 11.4878(8), c = 20.823(2) Å , β = 98.907(9)° and Z = 2; 2, triclinic in P1̅ with a = 10.5091(6), b = 11.0604(6), c = 11.2823(6) Å , α = 107.899(4)°, β = 91.436(4)°, γ = 112.918(4)° and Z = 1. The channels and cavities appearing in the packing of the molecules are occupied by uncoordinated water molecules. High magnetic moments up to 14.65 BM./f.u. have been observed at room temperature due to the combined moments of the individual lanthanide ions.

N-Chlor-Nitrenokomplexe des Molybdäns: MoF4(NCl) und [CH3CN-MoF4(NCl)] / N-Chloro-Nitrene Complexes of Molybdenum: MoF4(NCl) and [CH3CN-MoF4(NCl)]

1987 ◽  
Vol 42 (11) ◽  
pp. 1398-1402 ◽  
Author(s):  
Dieter Fenske ◽  
Karin Völp ◽  
Kurt Dehnicke
Keyword(s):  
Nmr Spectra ◽  
Room Temperature ◽  
Yellow Crystal ◽  
Trans Position ◽  
Crystal Data ◽  
Acetonitrile Molecule ◽  
X Ray ◽  
Data Space ◽  
Monomeric Complex ◽  
Independent Molecules

MoF4(NCl) has been prepared as a yellow crystal powder by the reaction of diluted fluorine with MoCl3(N3S2) at room temperature. The compound is associated via fluorine bridges, according to the IR spectrum. With acetonitrile, the monomeric complex [CH3CN -MoF4(NCl)] is obtained, which was characterized by its IR and 19F NMR spectra as well as by an X-ray structure determination. Crystal data: space group Pm, Z = 2 (1068 observed, independent reflexions, R = 0.03). Lattice dimensions at -90 °C: a = 507.1. b = 704.8, c = 995.8 pm, β = 102.02°. The unit cell contains two crystallographically independent molecules [CH3CN -MoF4(NCl)], the Mo≡N-Cl groups being linear (bond angles 176°, 178°) with bond lengths MoN = 172 and NCI = 159, 162 pm. In the trans position to the MoNCl group, the nitrogen atom of the acetonitrile molecule is coordinated.

Phase Transitions in Hoalga

1983 ◽  
Vol 21 ◽  
Author(s):  
M. Doukoure ◽  
D. Gignoux ◽  
F. Sayetat
Keyword(s):  
Thermal Expansion ◽  
Room Temperature ◽  
Magnetic Order ◽  
Magnetocrystalline Anisotropy ◽  
Exchange Interactions ◽  
Thermal Anomaly ◽  
Antiferromagnetic State ◽  
Hexagonal Symmetry ◽  
X Ray ◽  
Magnetic Structures

ABSTRACTHoAlGa is hexagonal at room temperature. It undergoes two magnetic transitions succesively at TN = 32 K from a paramagnetic to a triangular antiferromagnetic state where the Ho moments lie in the basal plane and at Tt = 18 K in the course of which the moments rotate toward c giving rise to a colinear antiferromagnetic arrangement. X-ray experiments performed between 5 and 300 K allow to determine the crystal evolution through the two transitions. The hexagonal symmetry is not lowered through the transitions; this result is compatible with the observed magnetic groups. The thermal expansion curves show a very anisotropic behaviour of the lattice parameters. The “c” parameter shrinks below TN and this anomaly is to be related to the magnetic order. Along a, a positive thermal anomaly appears below 70 K and this can be interpreted by crystal field effects. Stability of magnetic structures is discussed with regard to exchange interactions and magnetocrystalline anisotropy.

Synthesis and Magnetic Properties of CoAl2O4 Coated Co Solid Solution Nanocapsules

2010 ◽  
Vol 663-665 ◽  
pp. 1256-1259
Author(s):  
Gui Mei Shi ◽  
Ge Song ◽  
Shu Lian ◽  
Jin Bing Zhang
Keyword(s):  
Solid Solution ◽  
Photoelectron Spectrum ◽  
Room Temperature ◽  
Ferromagnetic State ◽  
Antiferromagnetic Order ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Core ◽  
New Type ◽  
The Magnetic Field

A new type of antiferromagnetic CoAl2O4 coated ferromagnetic Co solid solution is synthesized by arc-discharging. Typical HRTEM images show that the nanocapsules form in a core-shell structure. The size of the nanocapsules is in range of 10-90 nm and the thickness of the shell is about 3-10 nm. X-ray photoelectron spectrum (XPS) and X-ray diffraction (XRD) reveal that the core consists of Co solid solution, while the shell is CoAl2O4. The magnetic field and temperature dependence of magnetizations confirm that the Co solid solution nanocapsules are basically in the ferromagnetic state below Curie temperature. In addition, the antiferromagnetic order occurs with Neél temperature TN of about 5 K. The saturation magnetization of Ms = 76.1 Am2/kg and the coercive force of Hc= 23.28 kA/m are achieved at room temperature for the Co solid solution nanocapsules.

Identification of Nanocrystalline Inclusions in Bismuth-Doped Silica Fibers and Preforms

2016 ◽  
Vol 22 (5) ◽  
pp. 987-996 ◽  
Author(s):  
Liudmila D. Iskhakova ◽  
Filipp O. Milovich ◽  
Valery M. Mashinsky ◽  
Alexander S. Zlenko ◽  
Sergey E. Borisovsky ◽  
...  
Keyword(s):  
Optical Fibers ◽  
Room Temperature ◽  
Optical Loss ◽  
Laser Generation ◽  
Dopant Distribution ◽  
X Ray ◽  
The Core ◽  
Silica Fibers ◽  
Transmission Electron ◽  
Bismuth Concentration

AbstractThe nature of nanocrystalline inclusions and dopant distribution in bismuth-doped silicate fibers and preforms are studied by scanning and transmission electron microscopy, and energy and wavelength-dispersive X-ray microanalysis. The core compositions are Bi:SiO2, Bi:Al2O3–SiO2, Bi:GeO2–SiO2, Bi:Al2O3–GeO2–SiO2, and Bi:P2O5–Al2O3–GeO2–SiO2. Nanocrystals of metallic Bi, Bi2O3, SiO2, GeO2, and Bi4(GeO4)3 are observed in these glasses. These inclusions can be the reason for the background optical loss in bismuth-doped optical fibers. The bismuth concentration of 0.0048±0.0006 at% is directly measured in aluminosilicate optical fibers with effective laser generation (slope efficiency of 27% at room temperature).

Spaltung von S4N4 zu S2N2 bei Raumtemperatur: Darstellung und Struktur von S2N2 • 2AlBr3 / Cleavage of S4N4 to S2N2 at Room Tem perature: Preparation and Structure of S2N2 • 2AlBr3

1984 ◽  
Vol 39 (2) ◽  
pp. 145-148 ◽  
Author(s):  
Ulf Thewalt ◽  
Konrad Holl
Keyword(s):  
Molecular Structure ◽  
Room Temperature ◽  
Crystal And Molecular Structure ◽  
Crystal Data ◽  
X Ray Diffraction ◽  
X Ray ◽  
Bond Lengths

The compound S2N2 • 2AlBr3 has been prepared by reaction of S4N4 with AlBr3 in 1,2-dibromoethane at room temperature. Its crystal and molecular structure have been determined by X-ray diffraction; R = 0.068. Crystal data: monoclinic, P 21/n, a = 9.594(5), b = 9.975(4), c = 7.528(4) Å , β = 111.36(5)°. The S2N2 ring of the centrosymmetrical complex is bonded via its nitrogen atoms to two AlBr3 units thus completing coordination tetrahedra around the Al atoms. Bond distances and angles within the S2N2 ring are d(S-N) = 1.629(13) and 1.651(13) Å, ∢ (S-N-S) = 95.8, and ∢ (N-S-N) - 84.2°. Whereas the S-N bond lengths agree closely with those of free S2N2, the angle at N is enlarged by ca. 5° and the angle at S is decreased by ca. 5°. The sulfur atoms form two close S···Br contacts of length 3.149 (intramolecular) and 3.193 (intermolecular) Å , respectively. The intermolecular attractive nonbonded S···Br interactions tie the complexes together in a way that leads to infinite chains which run parallel to the crystallographic z axis

Structure of TlSr2PrCu207−x by Rietveld analysis

1994 ◽  
Vol 9 (3) ◽  
pp. 194-199
Author(s):  
Hoong-Kun Fun ◽  
Ping Yang ◽  
Rusli Othman ◽  
Tsong-Jen Lee ◽  
Chiou-Chu Lai ◽  
...  
Keyword(s):  
Low Temperature ◽  
Crystalline Structure ◽  
Powder Diffraction ◽  
Room Temperature ◽  
Goodness Of Fit ◽  
Rietveld Analysis ◽  
Crystal Data ◽  
X Ray ◽  
Tetragonal System

The crystalline structure of new TlSr2PrCu207−x was obtained at room temperature (300 K) and low temperature (100 K) from X-ray powder diffraction with CuKα radiation using Rietveld analysis. TlSr2PrCu207−x has an isotypical structure with TlBa2CaCu207 (1212). At 300 K, crystal data: Tl0.864Sr2PrCu2O6.75, Mr=727.811, the tetragonal system, P4/mmm, a =3.85404(5) Å, c = 12.1046(2) Å, V=179.80 Å3, Z=1, Dx =6.7218 g cm−3, μ =1143.922 cm−1 (λ = 1.54051 Å), F(000)=317.0, the structure was refined with 28 parameters to Rwp=5.29%, Rp = 3.65% for 3551 step intensities and Rb=7.40%, Rf=639% for 155 peaks, “goodness of fit” 5=3.05. At 100 K, crystal data: Tl0.858Sr2PrCu2O6.61, Mr=724.345, the tetragonal system, P4/mmm, a =3.84872(6) Å, c = 12.0771(3) Å, V=178.89 Å3, Z=1, Dx=6.7235 g cm−3, μ=1146.939 cm−1 (λ= 1.54051 Å), F(000) = 315.4, the structure was refined with 26 parameters to Rwp=6.70%, Rp=5.11% for 2926 step intensities and Rb=7.83%, Rf=6.70% for 131 peaks, “goodness of fit” S = 1.75.

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