Crystal structure and magnetic properties of the magnetically isolated zigzag chain in KGaCu(PO4)2

Magnetism of any material depends on its crystal structure. However, two isostructural compounds such as MCuMoO4(OH) (M = Na, K) can have markedly different magnetic properties. Herein, we introduce a new method to describe the linkages between the O-atoms and their bridged Cu2+ ions in order to clearly illustrate the structure-magnetic property relationships. This new method can account for magnetic differences between the two isostructural MCuMoO4(OH) and is further confirmed by the rational design and development of a new compound KGaCu(PO4)2 with different linkages. The title compound crystalized in a space group of P21/c adopts a one-dimensional (1D) magnetically isolated S = 1/2 zigzag chain composed of elongated [CuO6] octahedra via sharing alternately equatorial and skew edges. O atoms at the skew edges bridge the equatorial and axial orbitals of neighbouring Cu2+ ions (denoted EOA), while those at the equatorial edges bridge the equatorial orbitals of Cu2+ ions (EOE). The nearest-neighbour (NN) magnetic coupling of Cu2+ ions with the EOA linkage at 2.821 Å in the title compound is negligible, whereas the NN magnetic coupling of Cu2+ ions with the EOE linkage at 2.974 Å is essential. Therefore, the zigzag chain containing alternating spin-exchange dimers and no-spin-exchange ones is similar in electronic configuration to the dimerization of the quasi-one-dimensional antiferromagnet. Magnetic investigation of analogous compounds with a 'trans-cis-trans-cis' configuration observed in the title compound may shed light on structural evolutions associated with spin-Peierls (SP) transition.

A 3D Cu(ii) tetrazolate coordination polymer based on pentanuclear units with a large coercive field

A 3D Cu(ii) coordination polymer with the ligand 1,2-bis(tetrazol-5-yl) exhibits spin-canting magnetic behavior with a large coercive field of 2.3 kOe.

Two tartratoborates with hybrid anionic groups from unusual condensation reactions

Two novel tartratoborates, namely, K₂[(C₄H₂O₆)(B₃O₄H)](H₂O) (1) and KCu₂[(C₄H₂O₆)₂B](H₂O)_2.5 (2), have been successfully synthesized by solvothermal reactions. They feature different kinds of structural types based on hybrid borate-tartrate motifs. The structure of compound 1 features a 3D network composed of novel [(C₄H₂O₆)₂(B₃O₄H)₂]^4- anionic groups interconnected by K⁺ cations. The [(C₄H₂O₆)₂(B₃O₄H)₂]^4- anion was formed by the condensation of two (B₃O₈H)^6- groups and two tartrate anions, and such condensation reaction has never been reported previously. Compound 2 exhibits a novel 3D network structure in which 2D {Cu₂[(C₄H₂O₆)₂B](H₂O)₂}^- layers are further interconnected via K⁺ ions. The [(C₄H₂O₆)₂B]^5- anion was formed by the condensation of two tartrate anions with a B(OH)₄^- unit. Magnetic measurements reveal a dominant antiferromagnetic interaction between neighboring Cu²⁺ ions in compound 2. Furthermore, UV-vis and infrared spectra and thermal analyses were also performed.

Na2Cu7(SeO3)4O2Cl4: a selenite chloride compound with Cu7 units showing spin-frustration and a magnetization plateau

A selenite chloride, Na2Cu7(SeO3)4O2Cl4 (), was prepared via a conventional hydrothermal method. Na2Cu7(SeO3)4O2Cl4 crystallizes in the triclinic space group P1[combining macron] and features an isolated reverse triangular dipyramid Cu7, which is assembled with two corner-shared Cu4 tetrahedral units. Magnetic measurements suggest that shows the spin-frustration effect with antiferromagnetic ordering at ∼5 K, while an unusual magnetization plateau is observed at an applied field of >4 T.

Spin-frustration in a new spin-1/2 oxyfluoride system (Cu13(VO4)4(OH)10F4) constructed by alternatively distorted kagome-like and triangular lattices

A novel copper compound, Cu13(VO4)4(OH)10F4, featuring two types of two-dimensional extended kagome-like and triangular lattices, exhibits long-range antiferromagnetic ordering at ∼3 K, a strong spin-frustration effect with f = 21 and a spin-flop transition at 5 T.

Structural and magnetic studies on three new mixed metal copper(II) selenites and tellurites

Three new transition metal copper(II) selenites or tellurites, namely, CdCu(SeO3)2 (1), HgCu(SeO3)2 ()2, and Hg2Cu3(Te3O8)2 (3), have been obtained by conventional hydrothermal reactions of CdO (or Hg2Cl2), CuO and SeO2 (or TeO2). Compounds 1 and 2 are isostructural and crystallize in P2(1)/c. Their structures feature a 3D anionic framework of Cu(SeO3)2(2-) with 1D channels of eight-membered rings (MRs) along the c-axis and a-axis, respectively, which are filled by Cd(2+) or Hg(2+) cations. Compound 3 crystallizes in a tetragonal system of space group P42(1)2. Its structure is characterized by a [Cu3(Te3O8)2](2-) honeycomb layer composed of [Te3O8](4-) anions interconnected by Cu(2+) ions with 1D channels of 8-MRs along the c-axis. TOPOS analysis indicates that the copper(ii) tellurite layer exhibits a new topological structure with a Schläfli symbol of {4(6)·8(9)}(2){4(6)}(3). The above anionic copper(II) tellurite layers are further linked by dumbbell Hg2(2+) cations to form a novel 3D framework. Magnetic measurements based on magnetic susceptibility and heat capacity indicate that compounds 1 and 2 show a spin-singlet ground state with a spin gap based on the [Cu2O8](12-) dimeric model, whereas compound e3 xhibits a 2D spin-system with an antiferromagnetic ordering around 25 K correlated with its honeycomb [Cu3(Te3O8)2](2-) layer. Furthermore, crystalline structures, thermal stabilities, IR spectra and UV-Vis diffuse reflectance spectra have also been studied.

Dimanganese(II) hydroxide vanadate, Mn2(OH)[VO4]

Dimanganese(II) hydroxide vanadate was obtained from hydro-thermal reactions. The crystal structure of the title compound is isotypic with that of Zn2(OH)[VO4]. Three crystallographically independent Mn(2+) ions are present, one (site symmetry .m.) with a distorted trigonal-bipyramidal and two (site symmetries .m. and 1) with distorted octa-hedral coordination spheres. These polyhedra are linked through common edges, forming a corrugated layer-type of structure extending parallel to (100). A three-dimensional framework results via additional Mn-O-V-O-Mn connectivities involving the two different tetra-hedral [VO4] units (each with point-group symmetry .m.). O-H⋯O hydrogen bonds (one bifurcated) between the OH functions (both with point-group symmetry .m.) and the [VO4] units complete this arrangement.