共查询到20条相似文献,搜索用时 15 毫秒
1.
J. Escobal J.L. Mesa J.M. Rojo M.I. Arriortua 《Journal of solid state chemistry》2005,178(9):2626-2634
The Ni3(PO4)2 phosphate was synthesized by the ceramic method in air atmosphere. The crystal structure consists of a three-dimensional skeleton constructed from Ni3O14 edge-sharing octahedra, which are interconnected by (PO4)3− oxoanions with tetrahedral geometry. The magnetic behavior was studied on powdered sample by using susceptibility, specific heat and neutron diffraction data. The nickel(II) orthophosphate exhibits a three-dimensional magnetic ordering at approximately 17.1 K. However, its complex crystal structure hampers any parametrization of the J-exchange parameter. The specific heat measurements of Ni3(PO4)2 exhibit a three-dimensional magnetic ordering (λ-type) peak at 17.1 K. Measurements above TN suggest the presence of a small short-range order in this phase. The total magnetic entropy was found to be 28.1 KJ/mol at 50 K. The magnetic structure of the nickel(II) phosphate exhibits ferromagnetic interactions inside the Ni3O14 trimers which are antiferromagnetically coupled between them, giving rise to a purely antiferromagnetic structure. 相似文献
2.
Theocharis C. StamatatosCatherine P. Raptopoulou Spyros P. PerlepesAthanassios K. Boudalis 《Polyhedron》2011,30(18):3026-3033
The combined use of di-2-pyridyl ketone [(py)2CO] and azides (N3−) in nickel(II) and cobalt(II) pivalate chemistry has afforded complexes [Ni9(N3)2(O2CCMe3)8{(py)2CO2}4] (1) and [Co9(N3)2(O2CCMe3)8{(py)2CO2}4] (2), where (py)2CO22− is the gem-diolate(−2) form of (py)2CO. The complexes are isostructural and crystallize in the monoclinic P21/c space group. Their molecular structures consist of nine metal(II) ions, eight of which are arranged as two parallel squares flanking the ninth. DC magnetic susceptometry on powdered samples of 1 (1-p) reveal an overall antiferromagnetic behavior, leading to an S = 0 ground state. AC susceptometry reveals out-of-phase signals between 10 and 27 K, and ZFC and FC experiments show a divergence of the two curves below ∼27 K. Magnetization-decay and field-sweep experiments verify the relaxation behavior of the sample. Samples of the complex arising from carefully washed single crystals (1-cr) reveal a similar DC behavior, without however the appearance of cusps in the χΜΤ versus T curves, and no relaxation. The relaxation behavior has been assigned to NiO impurities. The results illustrate the extreme care that should be taken when examining the magnetic properties of apparently analytically pure materials obtained under heating. Complex 2 exhibits an overall antiferromagnetic behavior, without observation of any relaxation phenomena. 相似文献
3.
Yukio Hinatsu Yuki Izumiyama Abdolali Alemi Makoto Wakeshima Yukio Morii 《Journal of solid state chemistry》2004,177(1):38-44
Magnetic properties of double perovskite compounds Ba2HoRuO6 and Ba2HoIrO6 have been reported. Powder X-ray and neutron diffraction measurements show that these compounds have a cubic perovskite-type structure with the space group and the 1:1 ordered arrangement of Ho3+ and Ru5+ (or Ir5+) over the 6-coordinate B sites. Results of the magnetic susceptibility and specific heat measurements show that Ba2HoRuO6 exhibits two magnetic anomalies at 22 and 50 K. Analysis of the temperature dependence of magnetic specific heat indicates that the anomaly at 50 K is due to the antiferromagnetic ordering of Ru5+ ions and that the anomaly at 22 K is ascribable to the magnetic interaction between Ho3+ ions. Neutron diffraction data collected at 10 and 35 K show that the Ba2HoRuO6 has a long range antiferromagnetic ordering involving both Ho3+ and Ru5+ ions. Each of their magnetic moments orders in a Type I arrangement and these magnetic moments are anti-parallel in the ab-plane with each other. The magnetic moments are aligned along the c-direction. On the other hand, Ba2HoIrO6 is paramagnetic down to 1.8 K. 相似文献
4.
Ramon S. Vilela Thiago L. Oliveira Felipe T. Martins Javier A. Ellena Francesc Lloret Miguel Julve Danielle Cangussu 《Comptes Rendus Chimie》2012,15(10):856-865
The preparation, crystal structure and magnetic properties of a new oxalate-containing copper(II) chain of formula {[(CH3)4N]2[Cu(C2O4)2] · H2O}n (1) [(CH3)4N+ = tetramethylammonium cation] are reported. The structure of 1 consists of anionic oxalate-bridged copper(II) chains, tetramethylammoniun cations and crystallization water molecules. Each copper(II) ion in 1 is surrounded by three oxalate ligands, one being bidentate and the other two exhibiting bis-bidenate coordination modes. Although all the tris-chelated copper(II) units from a given chain exhibit the same helicity, adjacent chains have opposite helicities and then an achiral structure results. Variable-temperature magnetic susceptibility measurements of 1 show the occurrence of a weak ferromagnetic interaction through the oxalate bridge [J = +1.14(1) cm−1, the Hamiltonian being defined as H = –J ∑nmSi · Sj]. This value is analyzed and discussed in the light of available magneto-structural data for oxalate-bridged copper(II) complexes with the same out-of-plane exchange pathway. 相似文献
5.
6.
The interaction of diethyl (pyridyn-2-ylmethyl)phosphonate (2-pmpe) with Cu(NO3)2 · 6H2O leads to a partial hydrolysis of the starting ligand and formation of the compound of the formula Cu2(2-mpmpe)2(H2O)2(NO3)2, where 2-mpmpe = monoethyl (pyridyn-2-ylmethyl)phosphonate. The crystal and molecular structure of a copper(II) compound was determined by single X-ray diffraction method. Its structure consists of five-coordinated in distorted square planar geometry (CuNO4 chromophore) copper(II) ions doubly bridged by OPO from phosphonate. The Cu?Cu distance is 4.69 Å. The crystal packing is determined by the interdinuclear hydrogen bond system, which leads to a three-dimensional (3D) H-bonds network. The compound was characterized by infrared, ligand field, EPR spectroscopy, and magnetic studies. The magnetic properties of the title compound investigated over the 1.8–300 K, revealed the occurrence of a weak ferromagnetic coupling through phosphonate bridge (J = 1.86 cm−1) and interdimer superexchange coupling through H-bond network (zJ′ = −0.17 cm−1). Spectroscopic and magnetic properties are presented in the light of crystal structure. 相似文献
7.
The crystal structure of Na3RuO4 determined by powder neutron diffraction is reported. The structure consists of isolated tetramers of edge sharing RuO6 octahedra in the ab plane, creating isolated four-member plaquettes of Ru atoms comprised of two equilateral triangles sharing an edge. Magnetic susceptibility measurements reveal an antiferromagnetic transition at ∼29 K, with . Neutron diffraction data indicate the onset of three-dimensional magnetic ordering at 29 K. 相似文献
8.
Magnetic properties of S=1/2 linear trimer cluster compounds A3Cu3(PO4)4 (A=Ca, Sr, and Pb) were investigated. Magnetic susceptibility data for the three compounds showed that paramagnetic copper spins form trimers with the total spin of 1/2 below about 45 K. Specific heat and magnetization measurements indicated that the trimer clusters undergo ferromagnetic long-range ordering at for A=Ca and antiferromagnetic long-range ordering at for A=Sr and for A=Pb. A3Cu3(PO4)4 exhibited 1/3-magnetization plateau at least up to magnetic field of 55 T at 1.3 and 4.2 K. A3Cu3(PO4)4 with A=Sr and Pb showed a spin-flop transition near 0.03 T in the antiferromagnetic state at 0.08 K. Specific heat data at magnetic fields clearly showed broad maxima at low temperatures due to the finite intra-chain interaction in one-dimensional arrays of the trimers. 相似文献
9.
Elvira M. Bauer Marcello Colapietro Said A. Ibrahim Gustavo Portalone 《Journal of solid state chemistry》2006,179(2):389-397
Co[(CH3PO3)(H2O)] (1) and Co[(C2H5PO3)(H2O)] (2) were prepared by the hydrothermal method and isolated as blue-violet platelet crystals. They were characterized by X-ray diffraction, FT-IR, TGA-DSC techniques and their magnetic properties studied by a dc-SQUID magnetometer. Compound (1) shows an hybrid layered structure, made of alternating inorganic and organic layers along the a-direction of the unit cell. The inorganic layers contain Co(II) ions six-coordinated by five phosphonate oxygen atoms and one from the water molecule. These layers are separated by bi-layers of methyl groups and van der Waals contacts are established between them. In compound (2), the layered hybrid structure is rather similar to that described for compound (1), but the alternation of the inorganic and organic layers is along the b-direction of the unit cell. The magnetic behavior of (1) and (2) as function of temperature and magnetic field was studied. The compounds obey the Curie-Weiss law at temperatures above 100 K, the Curie C, and Weiss θ constants for the methyl derivative being and and for the ethyl derivative and , respectively. The observed magnetic moments for Co atom at room temperature (i.e. μeff=5.18 and 5.38 BM, respectively) are higher than those expected for a spin-only value for high spin Co(II) (S=3/2), revealing a substantial orbital contribution to the magnetic moment. The negative values of θ are an indication of the presence of antiferromagnetic exchange couplings between the near-neighbors Co(II) ions, within the layers. [Co(CnH2n+1PO3)(H2O)] (n=1,2) are 2D Ising antiferromagnets at low temperatures. 相似文献
10.
I. de Pedro J.M. Rojo J. Rodríguez Fernández T. Rojo 《Journal of solid state chemistry》2011,184(8):2075-2082
The Co2−xCux(OH)AsO4 (x=0 and 0.3) compounds have been synthesized under mild hydrothermal conditions and characterized by X-ray single-crystal diffraction and spectroscopic data. The hydroxi-arsenate phases crystallize in the Pnnm orthorhombic space group with Z=4 and the unit-cell parameters are a=8.277(2) Å, b=8.559(2) Å, c=6.039(1) Å and a=8.316(1) Å, b=8.523(2) Å, c=6.047(1) Å for x=0 and 0.3, respectively. The crystal structure consists of a three-dimensional framework in which M(1)O5-trigonal bipyramid dimers and M(2)O6-octahedral chains (M=Co and Cu) are present. Co2(OH)AsO4 shows an anomalous three-dimensional antiferromagnetic ordering influenced by the magnetic field below 21 K within the presence of a ferromagnetic component below the ordering temperature. When Co2+ is partially substituted by Cu2+ions, Co1.7Cu0.3(OH)AsO4, the ferromagnetic component observed in Co2(OH)AsO4 disappears and the antiferromagnetic order is maintained in the entire temperature range. Heat capacity measurements show an unusual magnetic field dependence of the antiferromagnetic transitions. This λ-type anomaly associated to the three-dimensional antiferromagnetic ordering grows with the magnetic field and becomes better defined as observed in the non-substituted phase. These results are attributed to the presence of the unpaired electron in the dx2−y2 orbital and the absence of overlap between neighbour ions. 相似文献
11.
Victor N. Khrustalev Ivan A. Portnyagin Irina V. Borisova Mikhail Yu. Antipin 《Journal of organometallic chemistry》2005,690(4):1056-1062
New stable azido derivatives of divalent germanium and tin [N3-E14-OCH2CH2NMe2]2 (E14 = Ge (1), Sn (2)) have been synthesized by use of the β-dimethylaminoethoxy ligand that forms the intramolecular E14 ← N coordination bond. Their crystal structures have been determined by X-ray diffraction analysis. Compounds 1 and 2 are centrosymmetric dimers via two intermolecular dative E14 ← O interactions with essentially linear monodentate azide ligands. The dominant canonical form of the E14-azide moieties is E14-N-NN. 相似文献
12.
Two novel Ni(II) complexes {[Ni(en)2(pot)2]0.5CHCl3} (3) {pot = 5-phenyl-1,3,4-oxadiazole-2-thione} (1) and [Ni(en)2](3-pytol)2 (4) {3-pytol = 5-(3-pyridyl)-1,3,4-oxadiazole-2-thiol} (2) have been synthesized using en as coligand. The metal complexes have been characterized by physical and analytical techniques and also by single crystal X-ray studies. The complexes 3 and 4 crystallize in monoclinic system with space group P21/a and P121/c, respectively. The complex 3 has a slightly distorted octahedral geometry with trans (pot)− ligands while 4 has a square planar geometry around the centrosymmetric Ni(II) center with ionically linked trans (3-pytol)− ligands. The π?π (face to face) interaction plays an important role along with hydrogen bondings to form supramolecular architecture in both complexes. 相似文献
13.
The crystal structure of the quasi-one-dimensional oxide PbNi1.88Mg0.12V2O8 has been studied by Rietveld analysis of combined high-resolution neutron and X-ray powder diffraction data at 300 K and at low temperatures. The (Ni/Mg)O6 octahedral units share a common edge and form spiral chains along the c-axis of the tetragonal unit cell, without deviating the I41cd (Z=8) symmetry upon cooling. DC magnetic susceptibility measurements show that the system undergoes a magnetic phase transition below TN≅3.4 K. Rietveld analysis of the medium resolution neutron powder diffraction data confirms that impurity-induced antiferromagnetic order (with propagation vector, ) takes over from the Haldane ground state of the parent compound. The power-law [β=0.31(3)] temperature evolution of the strongest magnetic Bragg peak intensity indicates three-dimensional Ising-type magnetic interactions, while the reduced magnitude of the Ni2+ moment [〈μ〉=0.98(3) μB] suggests important zero-point spin fluctuations. Structural considerations are consistent with small changes in the interatomic distances around the bridging tetrahedral VO4 entities separating the chains. However, no bulk structural phase transition concurrent to the Néel ordering is found. We show that the modification of intra- and inter-chain Ni-Ni distances upon cooling promotes the magnetic coupling of the end-of-chain liberated S=1/2 spins and leads to antiferromagnetic ordering. 相似文献
14.
Pavel Kopel Jiří Kameníček Václav Petříček Aleš Kurečka Božena Kalinska Jerzy Mrozinski 《Polyhedron》2007
Nickel and copper complexes containing 1,3,5-benzenetricarboxylic acid, with a combination of selected N-donor ligands and Schiff bases, of the composition Ni3(bimz)6(btc)2 · 12H2O (1), Ni3(btz)9(btc)2 · 12H2O (2), Ni2(L1)(btc) · 7H2O (3), Ni3(L2)2(Hbtc) · 9H2O (4), Ni2(L3)(btc) · 4H2O (5), Cu2(L4)(btc) · 7H2O (6), [Cu3(pmdien)3(btc)](ClO4)3 · 6H2O (7) and [Cu3(mdpta)3(btc)](ClO4)3 · 4H2O (8); H3btc = 1,3,5-benzenetricarboxylic acid, bimz = benzimidazole, btz = 1,2,3-benztriazole, L1 = 2-[(phenylimino)methyl]phenol, L2 = N,N′-bis-(salicylidene)propylenediamine, L3 = 2-{[(2-nitrophenyl)methylene]amino}phenol, L4 = 2-[(4-methoxy-phenylimino)methyl]phenol, pmdien = N,N,N′,N″,N″-pentamethyldiethylenetriamine, mdpta = N,N-bis-(3-aminopropyl)methylamine, have been synthesized. The complexes have been studied by elemental analysis, IR, UV–Vis spectroscopies, magnetochemical and conductivity measurements and selected compounds also by thermal analysis. The crystal and molecular structure of complex 8 was solved. The complex is trinuclear with btc3−-bridge. The coordination polyhedron around each copper atom can be described as a distorted square with a CuON3 chromophore formed by one oxygen atom of carboxylate and three nitrogen atoms of mdpta. The magnetic properties of 8 have been studied in the 1.8–300 K temperature range revealing a very weak antiferromagnetic exchange interaction with J = −0.56 cm−1 for g = 2.13(9). The antimicrobial activities against selected strains of bacteria were evaluated. It was found that only complex 5 is able to inhibit the growth of Staphylococcus strains. 相似文献
15.
Victor N. Khrustalev Ivan A. Portnyagin Irina V. Borisova Yuri A. Ustynyuk Valery Lunin 《Journal of organometallic chemistry》2005,690(5):1172-1177
New stable heteroleptic germanium(II) and tin(II) compounds [(SiMe3)2N-E14-OCH2CH2NMe2]n (E14 = Ge, n = 1 (1), Sn, n = 2 (2)) have been synthesized and their crystal structures have been determined by X-ray diffraction analysis. While compound 1 is monomer stabilized by intramolecular Ge ← N coordination, compound 2 is associated to dimer via intermolecular dative Sn ← O interactions. 相似文献
16.
Makoto Wakeshima Nobuyuki Taira Aya Tobo Yasuo Yamaguchi 《Journal of solid state chemistry》2003,174(1):159-164
Magnetic and electrical properties are investigated for quaternary neodymium sulfides BaNd2TS5 (T=Co, Zn) through the specific heat, neutron diffraction, and electrical conductivity measurements. Their electrical conductivities show semiconductive behavior, which follows the Arrhenius temperature dependence with the activation energy of Ea=1.46 eV for BaNd2ZnS5 and Ea=1.19 eV for BaNd2CoS5. The specific heat of BaNd2ZnS5 has a λ-type anomaly at 2.8 K due to the antiferromagnetic ordering of the Nd3+ moments and a Schottky-type anomaly at around 60 K, which results from the crystal field splitting of the 4I9/2 ground state of the Nd3+ ion. The specific heat of BaNd2CoS5 shows two λ-type anomalies at 5.7 K due to the antiferromagnetic ordering of Nd3+ and at 58 K due to the antiferromagnetic ordering of Co2+. The latter overlaps with the Schottky-type anomaly due to the crystal field splitting of the Nd3+ ion. Neutron diffraction measurements for BaNd2CoS5 show that a magnetic arrangement of the Co2+ moments has a collinear antiferromagnetic structure, while that of the Nd3+ moments has a noncollinear one. 相似文献
17.
Zuzana Hugonin Mats Johnsson Sven Lidin Dirk Wulferding Peter Lemmens Reinhard K. Kremer 《Journal of solid state chemistry》2008,181(10):2776-2782
We report the synthesis, crystal structure determination, magnetic and low-temperature structural properties of a new cobalt antimony oxo-bromide. CoSb2O3Br2 crystallizes in the triclinic crystal system, space group P−1, with the following lattice parameters: a=5.306(3) Å, b=7.812(4) Å, c=8.0626(10) Å, α=88.54(3)°, β=82.17(3)°, γ=80.32(4)°, and Z=2. The crystal structure was solved from single crystal X-ray data and refined on F2, R1=3.08. The structure consists of layers made up by three building blocks, [CoO4Br2], [SbO3Br], and [SbO3] that are connected via edge- and corner-sharing so that structural Co-Co dimers are formed. The layers have no net charge and are only weakly connected by van der Waals forces to adjacent layers. Above ∼25 K the magnetic susceptibility is independent of the magnetic field and can be very well described by a Curie-Weiss law. Below 25 K the susceptibility passes through a maximum and decreases again that is typical for the onset of long-range antiferromagnetic correlations. Long-range antiferromagnetic ordering is observed below TN∼9 K indicating substantial inter-dimer exchange coupling between Co-Co dimers within the layers. However, according to the heat capacity results only a minute fraction of the entropy is associated with the long-range ordering transition. The phonon anomalies observed for T<6 K in Raman scattering and an anomaly in the specific heat point to a structural instability leading to a loss of inversion symmetry at lowest temperatures. 相似文献
18.
A three-dimensional (3D) cobalt phosphate: Co5(OH2)4(HPO4)2(PO4)2 (1), has been synthesized by hydrothermal reaction and characterized by single-crystal X-ray diffraction, thermogravimetric analysis, and magnetic techniques. The title compound is a template free cobalt phosphate. Compound 1 exhibits a complex net architecture based on edge- and corner-sharing of CoO6 and PO4 polyhedra. The magnetic susceptibility measurements indicated that the title compound obeys Curie-Weiss behavior down to a temperature of 17 K at which an antiferromagnetic phase transition occurs. 相似文献
19.
Sofia I. Pascu Karl S. Coleman Nicholas H. Rees 《Journal of organometallic chemistry》2005,690(6):1645-1658
Treatment of the bulky iminophosphine ligand [Ph2PCH2C(Ph)N(2,6-Me2C6H3)] (L) with [M(CH3CN)2(ligand)]+n, where for M = Pd(II): ligand = η3-allyl, n = 1, and for M = Rh(I), ligand: 2(C2H4), 2(CO) or cod, n = 0, yields the mono-cationic iminophosphine complexes [Pd(η3-C3H5)(L)][BF4] (1), [Rh(cod)(L)][BF4] (2), [Rh(CO)(CH3CN)(L)][BF4] (3), and cis-[Rh(L)2][BF4] (4). All the new complexes have been characterised by NMR spectroscopy and X-ray diffraction. Complex 1 shows moderate activity in the copolymerisation of CO and ethene but is inactive towards Heck coupling of 4-bromoacetophenone and n-butyl acrylate. 相似文献
20.
Deng-Ke Cao 《Journal of solid state chemistry》2006,179(2):573-578
This paper reports the syntheses and characterization of two phosphonate compounds Cd{(2-C5H4NO)CH(OH)PO3}(H2O)2 (1) and Zn{(4-C5H4NO)CH(OH)PO3} (2) based on hydroxy(2-pyridyl N-oxide)methylphosphonic and hydroxy(4-pyridyl N-oxide)methylphosphonic acids. Compound 1 has a chain structure in which dimers of edge-shared {CdO6} octahedra are linked by {CPO3} tetrahedra through corner-sharing. The pyridyl rings reside on the two sides of the inorganic chain. Compound 2 has a layer structure where the inorganic chains made up of corner-sharing {ZnO4} and {CPO3} tetrahedra are covalently connected by pyridyl N-oxide groups. Crystal data for 1: triclinic, space group , a=6.834(1) Å, b=7.539(1) Å, c=10.595(2) Å, α=84.628(3)°, β=74.975(4)°, γ=69.953(4)°. For 2: triclinic, space group , a=5.219(1) Å, b=8.808(2) Å, c=9.270(2) Å, α=105.618(5)°, β=95.179(4)°, γ=94.699(4)°. 相似文献