Nature of copper(II)-lanthanide(III) magnetic interactions and generation of a large magnetic moment with magnetic anisotropy of 3d-4f cyclic cylindrical tetranuclear complexes [CuIILLnIII(hfac)2]2, (H3L = 1-(2-hydroxybenzamido)-2-(2-hydroxy-3-methoxybenzylideneamino)ethane and Hhfac = hexafluoroacetylacetone,LnIII = Eu,Gd, Tb,Dy)

A cyclic cylindrical 3d-4f tetranuclear structure, in which the 3d and 4f magnetic ions are arrayed alternately, has been found to be a suitable molecular design to produce a large magnetic moment and large magnetic anisotropy. Complexes 3-10 with the chemical formula [MLLn(hfac)2]2 ((MII, LnIII) = (Cu, Eu) (3), (Cu, Gd) (4), (Cu, Tb) (5), (Cu, Dy) (6), (Ni, Eu) (7), (Ni, Gd) (8), (Ni, Tb) (9), (Ni, Dy) (10)) have been synthesized, where H3L = 1-(2-hydroxybenzamido)-2-(2-hydroxy-3-methoxybenzylideneamino)ethane and Hhfac = hexafluoroacetylacetone. The powder X-ray diffractions and FAB-mass spectra demonstrated that these complexes assume a similar tetranuclear structure. The crystal structures of 4 and 5 showed that each complex has a cyclic cylindrical tetranuclear CuII2LnIII2 structure, in which the CuII complex functions as a "bridging ligand-complex" to two adjacent LnIII ions. The temperature-dependent magnetic susceptibilities from 2 to 300 K and the field-dependent magnetizations at 2 K from 0 to 5 T have been measured for four pairs of CuII2LnIII2 and NiII2LnIII2, in which compound NiII2LnIII2 containing diamagnetic NiII ion was used as the reference complex to evaluate the CuII-LnIII magnetic interaction. Comparison of the magnetic properties of the CuII2LnIII2 complex with those of the corresponding NiII2LnIII2 complex showed that the magnetic interaction between CuII and EuIII ions is weakly ferromagnetic and that between CuII and either of GdIII, TbIII, and DyIII ions is ferromagnetic. Complex CuII2GdIII2, 4, has an S = 8 spin ground state, due to the ferromagnetic spin coupling between SGd = 7/2 and SCu = 1/2 with coupling constants of J1 = +3.1 cm-1 and J2 = +1.2 cm-1. The magnetic measurements showed that compounds 5 and 6, CuII2LnIII2 (LnIII = Tb, Dy), exhibit large magnetic moments and large magnetic anisotropy due to the LnIII ion.     

Microwave-assisted construction of ferromagnetic coordination polymers of [W(V)(CN)8]3- with Cu(II)-pyrazole synthons

The microwave-mediated self-assembly of [W(V)(CN)(8)](3-) with Cu(II) in the presence of pyrazole ligand resulted in the formation of three novel assemblies: Cu(II)(2)(Hpyr)(5)(H(2)O)[W(V)(CN)(8)](NO(3))·H(2)O (1), {Cu(II)(5)(Hpyr)(18)[W(V)(CN)(8)](4)}·[Cu(II)(Hpyr)(4)(H(2)O)(2)]·9H(2)O (2), and Cu(II)(4)(Hpyr)(10)(H(2)O)[W(V)(CN)(8)](2)(HCOO)(2)·4.5H(2)O (3) (Hpyr =1H-pyrazole). Single-crystal X-ray structure of 1 consists of cyanido-bridged 1-D chains of vertex-sharing squares topology. The structure of 2 reveals 2-D hybrid inorganic layer topology with large coordination spaces occupied by {Cu(Hpyr)(2)(H(2)O)(4)}(2+) ions. Compound 3 contains two types of cyanido-bridged 1-D chains of vertex-sharing squares linked together by formate ions in two directions forming hybrid inorganic-organic 3-D framework (I(1)O(2)). The magnetic measurements for 1-3 reveal a weak ferromagnetic coupling through Cu(II)-NC-W(V) bridges.     

Spin ½ Delafossite honeycomb compound Cu5SbO6

Cu(5)SbO(6) is found to have a monoclinic, Delafossite-derived structure consisting of alternating layers of O-Cu(I)-O sticks and magnetic layers of Jahn-Teller distorted Cu(II)O(6) octahedra in an edge sharing honeycomb arrangement with Sb(V)O(6) octahedra. This yields the structural formula Cu(I)(3)Cu(II)(2)Sb(V)O(6). Variants with ordered and disordered layer stacking are observed, depending on the synthesis conditions. The spin ? Cu(2+) ions form dimers in the honeycomb layer. The magnetic susceptibility measured between 5 and 300 K is characteristic of the presence of a singlet-triplet spin gap of 189 K. High resolution synchrotron X-ray diffraction studies indicate that changes in the intra- or interdimer distances between 300 and 20 K, such as might indicate an increase in strength of the Peierls-like distortion through the spin gap temperature, if present, are very small. A comparison to the NaFeO(2)-type Cu(2+) honeycomb compounds Na(3)Cu(2)SbO(6) and Na(2)Cu(2)TeO(6) is presented.     

Hydrothermal Synthesis, Crystal Structure and Magnetic Property of a Novel Pentanuclear Copper(II) Complex:[Cu_5(SIP)_2(HSIP)_2(H_2O)_(18)](H_2O)_5

The pentanuclear complex, Cu5(SIP)2(HSIP)2(H2O)18(H2O)5(H3SIP = 5-sulfoi-sophthalic acid), has been synthesized by the hydrothermal reaction of CuCl2 with NaH2SIP at 160 ℃, and characterized by single-crystal X-ray diffraction and IR spectrum.The crystal of the complex crystallizes in a triclinic system, space group P1-, with a = 7.0018(5), b = 11.9725(8), c = 19.0424(13) , α = 78.8540(10), β = 85.1710(10), γ = 83.6080(10)o, V = 1553.24(19) 3, Z = 1, C32H60O51S4Cu5, Mr = 1706.74, Dc = 1.825 g/cm3, μ = 1.937 mm-1, F(000) = 869, the final R = 0.0709 and wR = 0.1503 for 4235 observed reflections with I > 2σ(I).The five Cu2+ ions are connected by two symmetry-related tridentate SIP3-ligands and charge-balanced by two monodentate HSIP2-ligands, giving a discrete pentanuclear structure.The pentanuclear copper molecules are linked by hydrogen bonds to form a three-dimensional supramolecular structure.The temperature-dependent magnetic susceptibility data revealed weak ferromagnetic magnetic interactions between the Cu2+ ions.     

Hydrothermal Synthesis, Crystal Structure and Magnetic Property of a Novel Pentanuclear Copper(Ⅱ) Complex: [Cu5(SIP)2(HSIP)2(H2O)18](H2O)5

The pentanuclear complex, [Cu5(SIP)2(HSIP)2(H2O)18](H2O)5 (H3SIP=5-sulfoi-sophthalic acid), has been synthesized by the hydrothermal reaction of CuCl2 with NaH2SIP at 160 ℃, and characterized by single-crystal X-ray diffraction and IR spectrum. The crystal of the complex crystallizes in a trielinic system, space group P1, with a = 7.0018(5), b = 11.9725(8), c = 19.0424(13) A, α = 78.8540(10), β = 85.1710(10),γ = 83.6080(10)~, V = 1553.24(19) A3, Z = 1, C32H60O51S4Cu5, Mr= 1706.74, Dc= 1.825 g/cm3,μ = 1.937 mm-1, F(000) = 869, the final R = 0.0709 and wR = 0.1503 for 4235 observed reflections with I > 2σ(I). The five Cu2+ ions are connected by two symmetry-related tridentate SIP3- ligands and charge-balanced by two monodentate HSIP2- ligands, giving a discrete pentanuclear structure. The pentanuclear copper molecules are linked by hydrogen bonds to form a three-dimensional supramolecular structure. The temperature-dependent magnetic susceptibility data revealed weak ferromagnetic magnetic interactions between the Cu2+ ions.     

ZnVSe2O7 and Cd6V2Se5O21: new d10 transition-metal selenites with V(IV) or V(V) cations

Two new metal selenites with a combination of vanadium(IV) or vanadium(V) cations, namely, ZnVSe 2O 7 and Cd 6V 2Se 5O 21, have been synthesized by hydrothermal and high-temperature solid-state reactions, respectively. The structure of ZnVSe 2O 7 features a 3D network of vanadium(IV) selenite with 1D tunnels occupied by zinc(II) ions. The 3D network of vanadium(IV) selenite is formed by corner-sharing V (IV)O 6 octahedral chains bridged by selenite groups. In Cd 6V 2Se 5O 21, the interconnection of cadmium(II) ions by bridging and chelating selenite groups led to a 3D framework with large tunnels along the b axis, and the 1D chains of corner-sharing V (V)O 4 tetrahedra are inserted in the above large tunnels and are bonded to the cadmium selenite framework via Cd-O-V bridges. Both compounds exhibit broad emission bands in the blue-light region. Results of magnetic property measurements show there is significant antiferromagnetic interaction between V (4+) centers in ZnVSe 2O 7. The electronic structure calculations for both compounds have been also performed.     

Importance of the O-M-O bridges (M = V5+, Mo6+) for the spin-exchange interactions in the magnetic oxides of Cu2+ ions bridged by MO4 tetrahedra: spin-lattice models of Rb2Cu2(MoO4)3, BaCu2V2O8, and KBa3Ca4Cu3V7O28

The spin-lattice models relevant for the magnetic oxides Rb2Cu2(MoO4)3, BaCu2V2O8, and KBa3Ca4Cu3V7O28 were determined by evaluating the relative strengths of the spin-exchange interactions between their Cu2+ ions on the basis of spin dimer analysis. Our study shows that the O-M-O bridges (M = V5+, Mo6+) between the magnetic ions Cu2+, provided by the MO4 tetrahedra, are crucial for the spin-exchange interactions and hence for deducing the spin-lattice models needed to interpret the magnetic properties of these oxides. The spin-lattice model of Rb2Cu2(MoO4)3 is not a uniform chain but two interpenetrating spin ladders that interact weakly with geometric spin frustration. The spin-lattice model of BaCu2V2O8 is an alternating chain as expected, but the spin-exchange paths responsible for it differ from those expected. With respect to the strongest spin exchange of BaCu2V2O8, the spin exchange of KBa3Ca4Cu3V7O28 is only slightly weaker, but the strongest spin exchange of Rb2Cu2(MoO4)3 is much weaker. This difference in the spin-exchange strengths is caused by the difference in the bridging modes of the MO4 tetrahedra leading to these spin-exchange interactions.     

Structures and magnetic behavior of 1-, 2-, and 3D coordination polymers in the Cu(II)-dicyanamide-pyrimidine family

Using aqueous conditions, three new coordination polymers containing Cu(2+) cations, dicyanamide (dca) anions, and pyrimidine (pym) were isolated and structurally and magnetically characterized. Comprising the bulk of the product yield, Cu(dca)(2)(pym)(2), 1, crystallizes in the monoclinic space group P2(1)/c with a = 7.3569(5) A, b = 13.4482(9) A, c = 7.4559(5) A, beta = 98.984(3) degrees, and V = 728.6(1) A and forms linear 1D chains. The second compound, Cu(dca)(NO(3))(pym)(H(2)O), 2, is also monoclinic, P2(1)/n, with a = 7.6475(3) A, b = 12.2422(5) A, c = 11.0286(4) A, beta = 106.585(2) degrees, and V = 989.6(1) A(3). A 2D network structure consisting of both bridging mu-dca and pym ligands is formed while the NO(3)(-) and H(2)O are axially bonded to the Cu center. Cu(3)(dca)(6)(pym)(2).0.75H(2)O, 3, is triclinic, Ponemacr;, with a = 7.7439(4) A, b = 9.3388(5) A, c = 10.1779(5) A, alpha = 86.014(2) degrees, beta = 88.505(2) degrees, gamma = 73.623(2) degrees, and V = 704.46(9) A(3). The structure of 3 is quite unique in that [Cu(3)(pym)(2)](6+) trimers are interconnected via mu-dca ligands affording a complex 3D self-penetrating framework. Magnetically, 1 exhibits extremely weak exchange interactions along the Cu-(dca)(2)-Cu ribbons while 2 and 3 display very strong magnetic couplings mediated by the mu-bonded pym ligands. Moreover, 2 shows a broad maximum in chi(T) at 40 K and behaves as a uniform 1D antiferromagnetic chain with g = 2.09(1), J/k(B) = -42.6(1) K, and TIP = -66 x 10(-)(6) emu/mol. An S = (1)/(2) trimer model that includes intertrimer interactions successfully described the magnetic behavior of 3, yielding g = 2.10(1), J/k(B) = -69.4(5) K, theta = -0.28(3) K, and TIP = -180 x 10(-)(6) emu/mol. It is found that mu-bonded dca and pym ligands mediate very weak and very strong exchange interactions, respectively, between Cu(2+) centers.     

Ligand influences on copper molybdate networks: the structures and magnetism of [Cu(3,4'-bpy)MoO(4)], [Cu(3,3'-bpy)(0.5)MoO(4)], and [Cu(4,4'-bpy)(0.5)MoO(4)].1.5H(2)O

The reactions of a Cu(II) salt, MoO(3), and the appropriate bipyridine ligand yield a series of bimetallic oxides, [Cu(3,4'-bpy)MoO(4)] (1), [Cu(3,3'-bpy)(0.5)MoO(4)] (2), and [Cu(4,4'-bpy)(0.5)MoO(4)].1.5H(2)O (3.1.5H(2)O). The structures of 1-3 exhibit three-dimensional covalent frameworks, constructed from bimetallic oxide layers tethered by the dipodal organoimine ligands. However, the [CuMoO(4)] networks are quite distinct. For structure 1, the layer consists of corner-sharing [MoO(4)] tetrehedra and [CuN(2)O(3)] square pyramids, while the layer of 2 is constructed from [MoO(4)] tetrehedra and binuclear [Cu(2)O(6)N(2)] units of edge-sharing copper square pyramids. The oxide substructure of 3 consists of [MoO(4)] tetrahedra corner-sharing with tetranuclear clusters of edge-sharing [CuO(5)N] octahedra. Crystal data: C(10)H(8)N(2)O(4)CuMo (1), orthorhombic Pbca, a = 12.4823(6) A, b = 9.1699(4) A, c = 19.5647(9) A, V = 2239.4(1) A(3), Z = 8; C(5)H(4)NO(4)CuMo (2), triclinic P, a = 5.439(1) A, b = 6.814(1) A, c = 10.727(2) A, alpha = 73.909(4)(o), beta = 78.839(4)(o); gamma = 70.389(4)(o); V = 357.6(1) A(3), Z = 2; C(10)H(8)N(2)O(8)Cu(2)Mo(2).3H(2)O 3.1.5H(2)O, triclinic P, a = 7.4273(7) A, b = 9.2314(8) A, c = 13.880(1) A, alpha = 71.411(2)(o), beta = 88.528(2)(o), gamma = 73.650(2)(o), V = 863.4(1) A(3), Z = 2. The magnetic properties of 1-3 arise solely from the presence of the Cu(II) sites, but reflect the structural differences within the bimetallic oxide layers. Compound 1 exhibits magnetic behavior consistent with ferromagnetic chains which couple antiferromagnetically at low temperature. Compound 2 exhibits strong antiferromagnetic dimeric interactions, with the magnetic susceptibility data consistent with the Bleaney-Bowers equation. Similarly, the magnetic susceptibility of 3 is dominated by antiferromagnetic interactions, which may be modeled as a linear S = 1/2 Heisenberg tetramer.     

Structural and magnetic behavior of the kinked chain Cu(hfac)2(tan) and its relevance to Cu(NO3)2(tan) (hfac = hexafluoroacetylacetonate; tan = 1,4,5-triazanaphthalene)

When stoichiometric amounts of Cu(hfac)(2).H(2)O and 1,4,5-triazanaphthalene (tan) were combined in methanol, green crystals of Cu(hfac)(2)(tan) were formed. Its structure was determined at low temperature (P2(1)/c; a = 8.3308(4) A, b = 14.8945(7) A, c = 18.3046(10) A, beta = 99.298(2) degrees, V = 2241.5(3) A(3)) and found to consist of a novel kinked-chain arrangement where N atoms on opposite sides of the tan ligand bridge Cu(hfac)(2) moieties together. Long axial Cu-N bonds lead to rather weak (J/k(B) = -0.06(5) K) antiferromagnetic interactions according to a Bonner-Fisher fit of the magnetic susceptibility data. The magnetic behavior demonstrated by Cu(hfac)(2)(tan) contrasts markedly with that of Cu(NO(3))(2)(tan), as reported by Hatfield and co-workers, and is attributed to the differing orientations of the Cu d(x)2(-)(y)2 magnetic orbital.     

Ab initio study on the electronic, magnetic, and mechanical properties of CaCu3V4O12

The electronic, magnetic, and mechanical properties of CaCu3V4O12 are investigated by use of the density functional theory method. The calculated results indicate that CaCu3V4O12 is a half-metallic and ferrimagnetic compound. The magnetic coupling for Cu-V is antiferromagnetic, while those for Cu-Cu and V-V are ferromagnetic. The obtained elastic constants suggest that the compound is mechanically stable. The calculated oxidation states and density of states reveal the existence of a mixed valence for Cu and V. This supports the experimental observation of the mixed valence in Ca(2+)Cu(2+)Cu2(+)(V2(5+)V2(4+))O12.     

Solid state coordination chemistry of the copper(ii)-terpyridine/oxovanadium organophosphonate system: hydrothermal syntheses, structural characterization and magnetic properties

The hydrothermal reactions of CuSO4.5H2O, Na3VO4, 2,2':6':2'-terpyridine (terpy), and the appropriate organophosphonate ligand yield a series of materials of the Cu(ii)-terpy/oxovanadium organophosphonate family. The complexes exhibit distinct structures spanning one-, two- and three-dimensions and exhibiting diverse oxovanadium building blocks. Thus, [{Cu(terpy)}(V2O4)(O3PPh)(HO3PPh)2] (1) is one-dimensional and constructed from binuclear units of corner-sharing V(v) square pyramids. While [{Cu(terpy)}VO(O3PCH2PO3)] (2), [{Cu(terpy)}2(V4O10)(O3PCH2CH2PO3)] (3), and [{Cu(terpy)}(V2O4){O3P(CH2)3PO3}].2.5H(2)O (4.2.5H2O) are similarly one-dimensional, the V/O structural components consist of isolated V(iv) square pyramids, tetranuclear V(v) units of three tetrahedra and one square pyramid in a corner-sharing arrangement, and isolated V(v) tetrahedra and square pyramids, respectively. The second propylenediphosphonate derivative, [{Cu(terpy)}(V2O4){O3P(CH2)3PO3}] (5) is three-dimensional and exhibits isolated V(v) tetrahedra as the vanadate component. The two-dimensional structure of [{Cu(terpy)(H2O)}(V3O6){O3P(CH2)4PO3}] (6) is mixed valence with isolated V(iv) square pyramids and binuclear units of corner-sharing V(v) tetrahedra providing the V/O substructures.     

Interpretation of the magnetic structures of Cu2Te2O5X2 (X = Cl,Br) and Ca3.1Cu0.9RuO6 on the basis of electronic structure considerations: cases for strong super-superexchange interactions involving Cu2+ ions

For super-superexchange interactions between Cu(2+) ions, a qualitative rule was formulated to assess their strengths based on the geometrical parameters of the exchange paths. Spin dimer analysis was carried out for Cu(2)Te(2)O(5)X(2) (X = Cl, Br) and Ca(3.1)Cu(0.9)RuO(6) to evaluate the relative strengths of their superexchange and super-superexchange interactions. The strongest antiferromagnetic interactions in Cu(2)Te(2)O(5)X(2) (X = Cl, Br) are given by the super-superexchange interactions involving the most linear Cu-X.X-Cu paths between tetrahedral clusters Cu(4)O(8)X(4) along the (a +/- b)-directions. The adjacent CuRuO(6) chains of Ca(3.1)Cu(0.9)RuO(6) are antiferromagnetically coupled through the most linear Cu-O.O-Cu paths along the direction perpendicular to the plane of the CuRu zigzag chain. The spin lattices of Cu(2)Te(2)O(5)X(2) and Ca(3.1)Cu(0.9)RuO(6) deduced from our spin dimer analysis are consistent with the available magnetic data. The spin lattice of a magnetic solid should be determined on the basis of appropriate electronic structure considerations.     

Symmetry-based magnetic anisotropy in the trigonal bipyramidal cluster [Tp2(Me3tacn)3Cu3Fe2(CN)6]4+

Reaction of [(Me3tacn)Cu(H2O)2]2+ (Me3tacn = N,N',N' '-trimethyl-1,4,7-triazacyclononane) with [TpFe(CN)3]- (Tp- = hydrotris(pyrazolyl)borate) in a mixture of ethanol and acetonitrile affords the pentanuclear cluster [Tp2(Me3tacn)3Cu3Fe2(CN)6]4+. Single-crystal X-ray analysis reveals a trigonal bipyramidal structure featuring a D3h-symmetry core in which two opposing FeIII (S = 1/2) centers are linked through cyanide bridges to an equatorial triangle of three CuII (S = 1/2) centers. Fits to variable-temperature dc magnetic susceptibility data are consistent with ferromagnetic coupling to give an S = 5/2 ground state, while fits to low-temperature magnetization data indicate the presence of a large axial zero-field splitting (D = -5.7 cm-1). Frequency dependence observed in the ac magnetic susceptibility data confirms single-molecule magnet behavior, with an effective spin reversal barrier of Ueff = 16 cm-1. When compared with the much lower anisotropy barrier previously observed for the face-centered cubic cluster [Tp8(H2O)6Cu6Fe8(CN)6]4+, the results demonstrate the enormous influence of the geometry in which a given set of metal ions are arranged.     

Determination of the spin-lattice relevant for the quaternary magnetic oxide Bi4Cu3V2O14 on the basis of tight-binding and density functional calculations

The quaternary magnetic oxide Bi4Cu3V2O14 consists of Cu4O8 triple chains made up of corner-sharing CuO4 square planes. To determine its spin-lattice, the spin exchange interactions of Bi4Cu3V2O14 were evaluated by performing a spin dimer analysis based on tight-binding calculations and a mapping analysis based on first principles density functional theory calculations. Both calculations show that the spin-lattice of Bi4Cu3V2O14 is not an antiferromagnetically coupled diamond chain, which results from an idealized view of the structure of the Cu4O8 triple chain and a neglect of super-superexchange interactions. The correct spin-lattice is an antiferromagnetic chain made up of antiferromagnetic linear trimers coupled through their midpoints via super-superexchange interaction, which predicts that Bi4Cu3V2O14 has an antiferromagnetic spin ground state and has no spin frustration, both in agreement with experiment.     

Grid-type two-dimensional magnetic multinuclear metal complex: strands of ([CuII(mu-4,4'-bpy)]2+)n cross-linked by octacyanotungstate(V) ions

Reaction of the preorganized strands of ([Cu(II)(mu-4,4'-bpy)](2+))n (4,4'-bpy = 4,4'-bipyridine) with [W(V)(CN)(8)](3)(-) leads to a novel cyano-bridged Cu(II)(3)W(V)(2) complex [Cu(mu-4,4'-bpy)(DMF)(2)][Cu(mu-4,4'-bpy)(DMF)](2)[W(V)(CN)(8)](2).2DMF. 2H(2)O 1. The structure of 1 consists of the expected 2-dimensional grid-type network which is built of infinite ([Cu(II)(mu-4,4'-bpy)](2+))n chains cross-linked by octacyanotungstate units. The Cu(II)-NC-W(V)-CN-Cu(II) linkage exhibits the topology of a 3,2-chain. The skeleton of the layer is additionally stabilized by a hydrogen bond network formed by terminal cyano ligands of the [W(CN)(8)](3-) moiety and water molecules. The distance between the adjacent Cu(3)(II)W(2)(V) chains within the layer is 11.12 A along the a axis. The layers are connected by H-bonds of NCN-NDMF-NCN linkages into 3-D supramolecular architecture. The magnetic properties correspond to a dominant ferromagnetic coupling within the Cu(II)(3)W(V)(2) pentamer units (J = +35(4) cm(-1)) and much weaker effective AF interunit coupling which include both intra- and inter-3,2-chain interactions between pentamers (J' = -0.05(1) cm(-1)).     

Metal-biradical chains from a high-spin ligand and bis(hexafluoroacetylacetonato)copper(II)

The synthesis, X-ray crystal structure, and magnetic studies of a rare example of organic/inorganic spin hybrid clusters extended in infinite ladder-type chain [Cu(C5F6HO2)2]7(C35H35N5O4)2 ([Cu(hfac)2]7(pyacbisNN)2, 2) formed by the reaction of a high spin nitronylnitroxide biradical C35H35N5O4 (pyacbisNN, 1) and bis(hexafluroacetylacetonate)copper(II) = Cu(hfac)2 are described. Single-crystal X-ray structure analysis revealed the triclinic P1 space group of 2 with the following parameters: a = 10.6191(4) A, b = 19.6384(7) A, c = 21.941(9) A, alpha = 107.111(7) degrees, beta = 95.107(8) degrees, gamma = 94.208(0) degrees , Z = 2. Each repeating unit in 2 carries a centrosymmetric cyclic six spin and a linear five spin cluster with four different copper coordination environments having octahedral and square planar geometries. These clusters are interconnected to form infinite chains which are running along the crystallographic b axis. The magnetic measurements show nearly paramagnetic behavior with very small variations over a large temperature range. The magnetic properties are thus result of complex competitions of many weak ferro- and antiferromagnetic interactions, which appear as small deviations from quite linear mu(eff) vs T dependence at low temperature. At high temperature (300-14 K), antiferromagnetic behavior dominates a little, while at very low temperature (14-2 K), a small increase of mu(eff) was observed. The magnetic susceptibility data are described by the Curie-Weiss law [chi = C/(T - theta)] with the optimal parameters C = 4.32 +/- 0.01 emuK/mol and theta = - 0.6 +/- 0.3 K, where C is the Curie constant and theta is the Weiss temperature.     

Spin dimer analysis of the anisotropic spin exchange interactions in the distorted wolframite-type oxides CuWO4, CuMoO4-III, and Cu(Mo(0.25)W0.75)O4

The distorted wolframite-type oxides CuWO4 and CuMoO4-III have a structure in which CuO4 zigzag chains, made up of cis-edge-sharing CuO6 octahedra, run along the c-direction and hence exhibit low-dimensional magnetic properties. We examined the magnetic structures of these compounds and their isostructural analogue Cu(Mo(0.25)W0.75)O4 on the basis of the spin-orbital interaction energies calculated for their spin dimers. Our study shows that these compounds consist of two-dimensional (2D) magnetic sheets defined by one superexchange (intrachain Cu-O-Cu) and three super-superexchange (interchain Cu-O.O-Cu) paths, the strongly interacting spin units of these 2D magnetic sheets are the two-leg antiferromagnetic (AFM) ladder chains running along the (a + c)-direction, and the spin arrangement between adjacent AFM ladder chains leads to spin frustration. The similarities and differences in the magnetic structures of CuWO4, CuMoO4-III, and Cu(Mo(0.25)W0.75)O4 were discussed by examining how adjacent AFM ladder chains are coupled via the superexchange paths in the 2D magnetic sheets and how adjacent 2D magnetic sheets are coupled via another superexchange paths along the c-direction. Our study reproduces the experimental finding that the magnetic unit cell is doubled along the a-axis in CuWO(4) and along the c-axis in CuMoO4-III and predicts that the magnetic unit cell should be doubled along the a- and b-axes in Cu(Mo(0.25)W0.75)O4. In the understanding of the strength of a super-superexchange interaction, the importance of the geometrical factors controlling the overlap between the tails of magnetic orbitals was pointed out.     

新型氨基酸-钨砷多金属氧酸盐K6［Cu(Ala)2*(H2O)2］2［Cu4(H2O)2(AsW9O34)2］*16H2O的合成与晶体结构

The novel amino-acid-containing polyoxometalate K6［Cu(Ala)2(H2O)2］2［Cu4(H2O)2\5(AsW9O34)2］*16H2O was synthesized from the rea ction of K10［Cu4(H2O)2(AsW9O34)2］*20H2O with β-alanine. Its structure has been determined by single crystal X-ray diffraction. It crystallizes in the triclinic space group P1, with a=1.196 3(2) nm, b=1.536 5(3) nm, c=1.591 4(3) nm, α=93.97(3)°, β=110.88(3)°, γ=101.07(3)°, V=2.651 8(9) nm3 and Z=1. Least-squares refinement of the structure leads to R and Rw factors of 0.067 3 and 0.162 8, respectively. An unusual structural feature of the compound is that the polyanion ［Cu4(H2O)2(AsW9O34)2］10- is linked with the amino-acid complex of Cu2+ by a μ-oxygen atom.     

Syntheses and characterization of nine quaternary uranium chalcogenides among the compounds A2M3UQ6 (A = K, Rb, Cs; M = Pd, Pt; Q = S, Se)

Nine compounds from the series A(2)M(3)UQ(6) (A = K or Rb or Cs; M = Pd or Pt; Q = S or Se) were synthesized by reacting U, M, and Q in ACl or A(2)Q(x) fluxes. These compounds crystallize with eight formula units in the NaBa(2)Cu(3)O(6) structure type, in space group Fmmm of the orthorhombic system. The structure contains hexagons formed from six edge-sharing square-planar coordinated M atoms, which in turn edge-share with trigonal-prismatically coordinated U atoms, forming layers along (010). These layers are separated by A atoms. Electrical resistivity measurements along the [100] direction of Rb(2)Pd(3)US(6) show typical semiconductor behavior. Magnetic susceptibility measurements on Rb(2)Pd(3)US(6) display marked magnetic anisotropy and unusually low magnetic moments owing to crystalline electric field effects.