Magnetic properties of a new cobalt hydrogen vanadate with a dumortierite‐like structure: Co13.5(OH)6(H0.5VO3.5)2(VO4)6

The magnetic properties of a novel cobalt‐based hydrogen vanadate, Co_13.5(OH)₆(H_0.5VO_3.5)₂(VO₄)₆, are reported. This new magnetic material was synthesized in single‐crystal form using a conventional hydrothermal method. Its crystal structure was determined from single‐crystal X‐ray diffraction data and was also characterized by scanning electron microscopy. Its crystal framework has a dumortierite‐like structure consisting of large hexagonal and trigonal channels; the large hexagonal channels contain one‐dimensional chains of face‐sharing CoO₆ octahedra linked to the framework by rings of VO₄ tetrahedra, while the trigonal channels are occupied by chains of disordered V₂O₄ pyramidal groups. The magnetic properties of this material were investigated by DC magnetic measurements, which indicate the occurrence of antiferromagnetic interactions.     

Cadmium in tetragonal pyramidaler Koordination im Barium-Cadmium-Oxovanadat: Ba2Cd3(VO4)2(V2O7)

Cadmium in Square Pyramids of Oxygen in the Barium Cadmium Oxovanadate: Ba₂Cd₃(VO₄)₂(V₂O₇) Single crystals of Ba₂Cd₃(VO₄)₂(V₂O₇) have been prepared by crystallization of a melt of BaCO₃, CdO and V₂O₅. It shows orthorhombic symmetry, space group D? P2₁2₁2₁, a = 7.206(2), b = 9.978(1), c = 19.617(3) Å, Z = 4. The crystal structure is characterized by (VO₄)^3? and (V₂O₇)^4? groups, CdO₆ octahedra, BaO₁₂ and BaO₉ polyhedra and with respect to Cd containing oxides unusual square pyramids of O^2? around Cd²⁺. The observed [CdO₄] zickzack chains are connected by VO₄ tetrahedra, V₂O₇ double tetrahedra and CdO₅ pyramids, forming a tunnel structure along [100]. The tunnels are filled by barium.     

Magnesium perchlorate anhydrate,Mg(ClO4)2, from laboratory X‐ray powder data

The previously unknown crystal structure of magnesium perchlorate anhydrate, determined and refined from laboratory X‐ray powder diffraction data, represents a new structure type. The title compound was obtained by heating magnesium perchlorate hexahydrate at 523 K for 2 h under vacuum and it crystallizes in the monoclinic space group P2₁/c. The asymmetric unit contains one Mg (site symmetry on special position 2a), one Cl and four O sites (on general positions 4e). The structure consists of a three‐dimensional network resulting from the corner‐sharing of MgO₆ octahedra and ClO₄ tetrahedra. Each MgO₆ octahedron share corners with six ClO₄ tetrahedra. Each ClO₄ tetrahedron shares corners with three MgO₆ octahedra, with one O‐atom corner dangling. The ClO₄ tetrahedra are oriented in such a way that one‐dimensional channels parallel to [100] are formed between the dangling O atoms.     

Two caesium vanadium hydrogenphosphates with tunnelled structures: Cs2V2O3(PO4)(HPO4) and Cs2[(VO)3(HPO4)4(H2O)]·H2O

Dicaesium divanadium trioxide phosphate hydrogenphosphate, Cs₂V₂O₃(PO₄)(HPO₄), (I), and dicaesium tris[oxidovanadate(IV)] hydrogenphosphate dihydrate, Cs₂[(VO)₃(HPO₄)₄(H₂O)]·H₂O, (II), crystallize in the monoclinic system with all atoms in general positions. The structures of the two compounds are built up from VO₆ octahedra and PO₄ tetrahedra. In (I), infinite chains of corner‐sharing VO₆ octahedra are connected to V₂O₁₀ dimers by phosphate and hydrogenphosphate groups, while in (II) three vanadium octahedra share vertices leading to V₃O₁₅(H₂O) trimers separated by hydrogenphosphate groups. Both structures show three‐dimensional frameworks with tunnels in which Cs⁺ cations are located.     

Das erste Vanadium(III)‐Borophosphat: Darstellung und Kristallstruktur von CsV3(H2O)2[B2P4O16(OH)4]

The First Vanadium(III) Borophosphate: Synthesis and Crystal Structure of CsV₃(H₂O)₂[B₂P₄O₁₆(OH)₄] CsV₃(H₂O)₂[B₂P₄O₁₆(OH)₄] was prepared under mild hydrothermal conditions (T = 165 °C) from mixtures of CsOH_(aq), VCl₃, H₃BO₃, and H₃PO₄ (molar ratio 1 : 1 : 1 : 2). The crystal structure was determined by X‐ray single crystal methods (monoclinic; space group C2/m, No. 12): a = 958.82(15) pm, b = 1840.8(4) pm, c = 503.49(3) pm; β = 110.675(4)°; Z = 2. The anionic partial structure contains oligomeric units [BP₂O₈(OH)₂]^5–, which are built up by a central BO₂(OH)₂ tetrahedron and two PO₄ tetrahedra sharing common corners. V^III is octahedrally coordinated by oxygen of adjacent phosphate tetrahedra and OH groups of borate tetrahedra as well as oxygen of phosphate tetrahedra and H₂O molecules, respectively (coordination octahedra VO₄(OH)₂ and VO₄(H₂O)₂). The oxidation state +3 for vanadium was confirmed by measurements of the magnetic susceptibility. The trimeric borophosphate groups are connected via vanadium centres to form layers with octahedra‐tetrahedra ring systems, which are likewise linked via V^III‐coordination octahedra. Overall, a three‐dimensional framework constructed from VO₄(OH)₂ and VO₄(H₂O)₂ octahedra as well as BO₂(OH)₂ and PO₄ tetrahedra results. The structure contains channels running along [001], which are occupied by Cs⁺ in a distorted octahedral coordination (CsO₄(H₂O)₂).     

Darstellung,Ramanspektren und Kristallstrukturen von V2O3(SO4)2, K[VO(SO4)2] und NH4[VO(SO4)2]

Preparation, Raman Spectra, and Crystal Structures of V₂O₃(SO₄)₂, K[VO(SO₄)₂], and NH₄[VO(SO₄)₂] The oxo-sulfato-vanadates(V) V₂O₃(SO₄)₂, K[VO(SO₄)₂], and NH₄[VO(SO₄)₂] have been prepared as crystals suitable for X-ray structure determination. In all structures sulfate acts as an unidentate ligand only toward a single vanadium atom. The structure of V₂O₃(SO₄)₂ consists of a threedimensional network of pairs of cornershared VO₆ octahedra with one terminal oxygen atom each, and SO₄ tetrahedra. All oxygen atoms of the sulfate ions are coordinated. NH₄[VO(SO₄)₂] and K[VO(SO₄)₂] are isostructural. VO₆ octahedra with one terminal oxygen atom and pairs of sulfate tetrahedra form infinite chains by corner sharing. The chains are weakly interlinked to layers. The sulfate ions are distorted towards planar SO₃ molecules and single oxygen atoms attached to vanadium. This structural detail gives an explanation for the mechanism of the reversible reaction K[VO(SO₄)₂] ? K[VO₂(SO₄)] + SO₃ at 400°C. Raman spectra of the compounds have been recorded and interpreted with respect to their structures. Crystal data: V₂O₃(SO₄)₂, monoclinic, space group P2₁/a, a = 947.2(4), b = 891.3(3), c? 989.1(4) pm, β = 104.56(3)°, Z = 4, 878 unique data, R(R_w) = 0.039(0,033); K[VO(SO₄)₂], orthorhombic, space group P2₁2₁2₁, a = 495.3(2), b = 869.6(9), c = 1 627(1)pm, Z = 4, 642 unique data, R(R_w) = 0,11(0,10); NH₄[VO(SO₄)₂], orthorhombic, space group P2₁2₁2₁, a = 495.3(1), b = 870.0(2), c = 1 676.7(4)pm, Z = 4, 768 unique data, R(R_w) = 0.088(0.083).     

Ba[Co3(VO4)2(OH)2] with a regular Kagomé lattice

The new layered title compound, barium di‐μ‐hydroxido‐di‐μ‐vanadato‐tricobaltate(II), was prepared under low‐temperature hydrothermal conditions. Its crystal structure comprises Co²⁺ and O²⁻ ions in the Kagomé geometry. The octahedral Co₃O₆(OH)₂ Kagomé layers, made up of edge‐shared CoO₄(OH)₂ octahedra with Co on a site of 2/m symmetry, alternate along the c axis with barium vanadate heteropolyhedral layers, in which Ba is on a site of m symmetry and V is on a site of 3m symmetry. All three O atoms and the H atom also occupy special positions: two O atoms and the H atom are on sites with 3m symmetry and one O atom is on a site with m symmetry. Ba[Co₃(VO₄)₂(OH)₂] represents the first compound from the four‐component BaO–CoO–V₂O₅–H₂O system and its structure is topologically related to the minerals vesignieite, Ba[Cu₃(VO₄)₂(OH)₂], and bayldonite, Pb[Cu₃(AsO₄)₂(OH)₂].     

Isokite,CaMg(PO4)F0.8(OH)0.2, isomorphous with titanite

This study presents the first structural report of natural isokite (calcium magnesium phosphate fluoride), with the formula CaMg(PO₄)F_0.8(OH)_0.2 (i.e. some substitution of OH for F), based on single‐crystal X‐ray diffraction data. Isokite belongs to the C2/c titanite mineral group, in which Mg is on an inversion centre and the Ca, P and F/OH atoms are on twofold axes. The structure is composed of kinked chains of corner‐sharing MgO₄F₂ octahedra that are crosslinked by isolated PO₄ tetrahedra, forming a three‐dimensional polyhedral network. The Ca²⁺ cations occupy the interstitial sites coordinated by six O atoms and one F anion.     

Hydrothermal syntheses and crystal structures of two organic–inorganic hybrid molybdovanadates based on [V2Mo6(OH)2O24]4− and [VMo12O40]3− polyoxoanions

Two new organic–inorganic hybrid cobalt-molybdovanadates [Co(phen)₃]H₂[H₂V₂Mo₆O₂₆] · 7H₂O (1) and [Co(2,2′-bipy)₃][Na(H₂O)₇][VMo₁₂O₄₀] (2) have been hydrothermally synthesized and structurally characterized by elemental analyses, IR, UV, XPS spectroscopy, thermogravimetric (TG) analyses, and X-ray single crystal diffraction. The molecular structure of 1 consists of a [V₂Mo₆(OH)₂O₂₄]^4? polyoxoanion, a [Co(phen)₃]²⁺, two H⁺ and seven lattice water molecules. The structure of [V₂Mo₆(OH)₂O₂₄]^4? consists of six MoO₆ octahedra and two VO₄ tetrahedra; six MoO₆ octahedra are linked by edge-sharing oxygens forming a {Mo₆} ring, and two VO₄ tetrahedra cap opposite sides of the {Mo₆} ring. The molecular structural unit of 2 is constructed from a typical Keggin-type [VMo₁₂O₄₀]^3? polyoxoanion and a [Co(2,2′-bipy)₃]²⁺ cation and a Na⁺ countercation; Co²⁺ is coordinated by six nitrogens from three 2,2′-bipyridines forming a distorted octahedron.     

Mg7(AsO4)2(HAsO4)4: a new magnesium arsenate with a very strong hydrogen bond

A new compound, heptamagnesium bis­(arsenate) tetrakis(hydrogenarsenate), Mg₇(AsO₄)₂(HAsO₄)₄, was synthesized by a hydro­thermal method. The structure is based on a three‐dimensional framework of edge‐ and corner‐sharing MgO₆, MgO₄(OH)₂, MgO₅, AsO₃(OH) and AsO₄ polyhedra. Average Mg—O and As—O bond lengths are in the ranges 2.056–2.154 and 1.680–1.688 Å, respectively. Each of the two non‐equivalent OH groups is bonded to both an Mg and an As atom. One OH group is involved in a very short hydrogen bond [O⋯O = 2.468 (3) Å]. The formula unit is centrosymmetric, with all atoms in general positions except for one Mg atom, which has site symmetry . The compound is isotypic with Mn₇(AsO₄)₂(HAsO₄)₄ and M₇(PO₄)₂(HPO₄)₄, where M is Fe, Co or Mn.     

Crystal growth,structure, and properties of manganese orthovanadate Mn3(VO4)2

Manganese orthovanadate Mn₃(VO₄)₂ single crystals were grown for the first time from a flux of MnO/V₂O₅/MoO₃. The flux and oxygen partial pressure used are the key factors for the crystal growth and prevention of the oxidation of Mn²⁺ and the reduction of V⁵⁺ during the crystallization process. The reduction and oxidation chemistry of Mn₃(VO₄)₂ was studied. Mn₃(VO₄)₂ is isostructural with magnesium orthovanadate Mg₃(VO₄)₂, orthorhombic, space group Cmca, a=6.247(1) Å, b=11.728(2) Å, c=8.491(2) Å and Z=4, as determined by single crystal X-ray diffraction. Because it is a Mn²⁺ deficient spinel structure there are two-dimensional sheets of Mn²⁺O₆ octahedra within the structure which show unusual ferrimagnetic properties.     

Crystal Structure and Magnetic Properties of a Vanadium (IV) Pyrophosphate: Rb2V3P4O17

The crystal structure of Rb₂V₃P₄O₁₇ has been determined from single-crystal X-ray diffraction data. Rb₂V₃P₄O₁₇ crystallizes in the orthorhombic space group Pnma (No. 62) with a = 17.502(7), b = 7.292(2), c = 11.399(6) ų, V = 1455(1) ų, Z=4, R=0.0295, R_W = 0.0320 for 1129 unique reflections with I > 2.5 σ(I). The structure contains intersecting tunnels where the Rb⁺ cations are located. The framework can be described as consisting of V²O₁₀ units formed from one VO₅ square pyramid and one VO₆ octahedron sharing a corner, and infinite chains of corner-shared VO₆ octahedra, which are linked in three dimensions by pyrophosphate groups. The structural formula is Rb₂(VO)₃(P₂O₇)₂. A single-phase product can be obtained by heating appropriate amounts of Rb₄V₂O₇, VO₂, V, and P₂O₅ in an evacuated fused silica tube at 950°C. Powder magnetic susceptibility data confirm the presence of V⁴⁺ (d¹) ions without magnetic ordering down to 3 K.     

Barium vanadium(III) hydrogen ­phosphate,Ba3V2(HPO4)6

Hydro­thermally prepared Ba₃V₂(HPO₄)₆ contains a three‐dimensional network of V^IIIO₆ octahedra [d_av(V—O) = 2.014 (2) Å] and HPO₄ [d_av(P—O) = 1.537 (3) Å] tetrahedra, sharing vertices. 12‐coordinate Ba²⁺ cations [d_av(Ba—O) = 2.944 (4) Å] complete the structure.     

12‐Membered borophosphate rings in KNi5[P6B6O23(OH)13]

The title compound, potassium pentanickel hexaborophosphate tridecahydroxide, was synthesized under hydrothermal conditions from the NiCl₂–K₃PO₄–B₂O₃–K₂CO₃–H₂O system. The crystal structure was determined using single‐crystal X‐ray diffraction at 100 K. The KNi₅[P₆B₆O₂₃(OH)₁₃] phase is cubic. For the three crystallographically distinct Ni centers, two occupy sites with 3 symmetry, while the third Ni and the K atom are located on sites. The structure is built from alternating borate and phosphate tetrahedra forming 12‐membered puckered rings with K⁺ ions at the centers. These rings are arranged as in cubic dense sphere packing. A novel feature of the new crystal structure is the presence of linear trimers of face‐sharing [NiO₆] octahedra occupying the octahedral interstices of this sphere packing, and of single [NiO₆] octahedra in the tetrahedral interstices. All oxygen corners of the Ni octahedra are linked to phosphate or borate tetrahedra of the 12‐membered rings to form a mixed anionic framework.     

Synthesis and crystal structure of the binary molybdate Li8Bi2(MoO4)7

Single crystals of Li₈Bi₂(MoO₄)₇ were synthesized; the composition and crystal structure of this compound were determined from X-ray diffraction data (CAD-4 automatic diffractometer, MoK_a radiation, 1767 reflections, R = 0.031). The parameters of the tetragonal unit cell are as follows: a = 21.130, c = 5.287 Å, Z = 4, space group -14. The structure of the binary molybdate is a three-dimensional mixed framework of MoO₄ tetrahedra of four varieties, Bi eight-vertex potyhedra, and Li(l)O₆ and Li(2)O₆ octahedra. The large channels of the framework along the c axis contain MoO₄ tetrahedra of the fifth variety with Li(3)O₄ and Li(4)O₄ tetrahedra attached to them via common vertices and forming four symmetrically related chains of pyroxene type. The structure of Li₈Bi₂(MoO₄)₇ involves structural fragments of Li₃Fe(MoO₄)₃ and a-RbPr(MoO₄)₂ and is a new structural type in the class of binary molybdates and tungstates of uniand trivalent metals.     

Mg5TiO4(BO3)2

Single crystals of pentamagnesium titanium(IV) tetraoxide bis(borate), Mg₅TiO₄(BO₃)₂, were prepared by slow cooling of the melt from 1623 K in air. The crystal is isostructural with the mineral ludwigite (Mg₂FeO₂BO₃). The Mg and Ti atoms are coordinated by six O atoms and the B atom is coordinated by three O atoms. There are three Mg sites and one mixed site statistically occupied by Mg and Ti atoms. Atoms are at the following special positions: 2a (0, 0, 0) and 2d (0, , ) for two Mg atoms, 4g (x, y, 0) for the mixed Ti/Mg site and the BO₃ group, and 4h (x, y, ) for a third Mg and two oxide O atoms. MgO₆ and (Ti/Mg)O₆ octahedra are connected by sharing of edges to form zigzag folding layers along the c axis. Triangular prismatic tunnels are formed between the folding layers by sharing apical O atoms of the MgO₆ and (Ti/Mg)O₆ octahedra.     

Synthese und Kristallstruktur von Vanadium(III)‐borophosphat,V2[B(PO4)3]

Synthesis and Crystal Structure of Vanadium(III) Borophosphate, V₂[B(PO₄)₃] By reaction of boron phosphate, BPO₄, and vanadium(IV)‐oxide, VO₂, at 1050 °C a hitherto unknown vanadium(III)‐borophosphate is formed. Its composition was found to be V₂BP₃O₁₂, its structure was elucidated by single crystal X‐ray diffraction, the cell parameters are: a = b = 13.9882Å; c = 7.4515Å; α = β = 90°, γ = 120°; Z = 6; space group: P6 3/m. Noteworthy features of the structure are V₂O₉ units (two V^IIIO₆ octahedra connected via their faces) and isolated trisphosphatoborate groups, B(PO₄)₃. By shared oxide ions, the aforementioned groups are interconnected, thus forming a three dimensional network. The structural relation between the title compound and an analogous chromium compound is discussed.     

Double molybdate Tl2Mg4(MoO4)3: Synthesis, structure, and properties

Single crystals of molybdate Tl₂Mg₂(MoO₄)₃ are grown, and its crystal structure is refined in an X-ray diffraction experiment (an automated diffractometer, MoK _α radiation, 914 F(hkl) reflections, R = 0.0459). The crystal are cubic with a = b = c = 10.700(1) Å, V = 1225.0(2) ų, Z = 4, space group P2₁3. The mixed 3D framework of the structure is built of MoO₄ tetrahedra and two types of corner-sharing MgO₆ octahedra. Two types of thallium atoms occupy large interstices.     

Effect of thermal transformations of constituent polyhedra of the crystal structure on the properties of Cd2V2O7

Analysis of variations in the linear and angular parameters of constituent polyhedra of the cadmium pyrovanadate Cd₂V₂O₇ structure, namely, VO₄ tetrahedra and CdO₆ octahedra, as calculated from the results of in situ high-temperature X-ray diffraction experiments in the range from 25 to 900°C, showed that, in the range from 600 to 720°C, the thermal expansion coefficient (tec) of CdO₆ polyhedra is near zero, whereas VO₄ tetrahedra increase in volume, although less strongly than in other temperature ranges. A structural interpretation is given to anomalous temperature dependences of cadmium ion emission and electrical conductivity on the basis of different thermal behavior patterns of the constituent polyhedra of the Cd₂V₂O₇ structure.     

One-step mild hydrothermal method to prepare low valent sodium vanadium(III) monohydrogenphosphate: NaV(HPO4)2

Green colored single crystals of a reduced sodium vanadium(III) monohydrogenphosphate, NaV(HPO₄)₂, were grown using a one-step mild hydrothermal method. The in situ reduction of V⁵⁺ to V³⁺ was performed using copper acetate as the reducing agent. The title compound crystalizes in the monoclinic space group Cc and exhibits a three-dimensional crystal structure that consists of distorted VO₆ octahedra connected to PO₃(OH) tetrahedra that are further connected via Na cations. The compound exhibits simple paramagnetic behavior at high temperatures and a discontinuity near 5 K is likely due to the onset of magnetic coupling. The compound was also characterized by TGA, IR and UV–vis spectroscopies.