Heptairon bis(phosphate) tetrakis(hydrogenphosphate)

A new iron hydrogen phosphate, heptairon bis­(phosphate) tetrakis­(hydrogen­phosphate), Fe₇(PO₄)₂(HPO₄)₄, has been prepared hydro­thermally and characterized by single‐crystal X‐ray diffraction. The compound has one Fe atom on an inversion centre and is isostructural with Mn₇(PO₄)₂(HPO₄)₄ and Co₇(PO₄)₂(HPO₄)₄. The structure is based on a framework of edge‐ and corner‐sharing FeO₆, Fe₅ and PO₄ polyhedra, isotypic with that found in the mixed‐valence iron phosphate Fe₇(PO₄)₆. The Fe atoms in the title compound are purely in the divalent state, just like the Co atoms in Co₇(PO₄)₂(HPO₄)₄, the necessary charge balance being maintained by the addition of H atoms in the form of bridging Fe—OH—P groups.     

FeII2(PO4)(OH), a synthetic analogue of wolfeite

This paper reports the hydrothermal synthesis and crystal structure refinement of diiron(II) phosphate hydroxide, Fe^II₂(PO₄)(OH), obtained at 1063 K and 2.5 GPa. This phosphate is the synthetic analogue of the mineral wolfeite, and has a crystal structure topologically identical to those of minerals of the triplite–triploidite group. The complex framework contains edge‐ and corner‐sharing FeO₄(OH) and FeO₄(OH)₂ polyhedra, linked via corner‐sharing to the PO₄ tetrahedra (average P—O distances are between 1.537 and 1.544 Å). Four five‐coordinated Fe sites are at the centers of distorted trigonal bipyramids (average Fe—O distances are between 2.070 and 2.105 Å), whereas the coordination environments of the remaining Fe sites are distorted octahedra (average Fe—O distances are between 2.146 and 2.180 Å). The Fe—O distances are similar to those observed in natural Mg‐rich wolfeite, except for two Fe—O bond distances, which are significantly longer in synthetic Fe²⁺₂(PO₄)(OH).     

The solid solution (Fe0.81Al0.19)(H2PO4)3 with a strong hydrogen bond

Single crystals of the solid solution iron aluminium tris(dihydrogenphosphate), (Fe_0.81Al_0.19)(H₂PO₄)₃, have been prepared under hydrothermal conditions. The compound is a new monoclinic variety (γ‐form) of iron aluminium phosphate (Fe,Al)(H₂PO₄)₃. The structure is based on a two‐dimensional framework of distorted corner‐sharing MO₆ (M = Fe, Al) polyhedra sharing corners with PO₄ tetrahedra. Strong hydrogen bonds between the OH groups of the H₂PO₄ tetrahedra and the O atoms help to consolidate the crystal structure.     

CsAlZr2(PO4)4: an anhydrous aluminium zirconium phosphate with a novel three‐dimensional framework

Caesium aluminium dizirconium tetrakis[phosphate(V)], CsAlZr₂(PO₄)₄, has been synthesized by high‐temperature reaction and studied by single‐crystal X‐ray diffraction at room temperature. This represents the first detailed structural analysis of an anhydrous phosphate containing both zirconium and aluminium. The structure features a complicated three‐dimensional framework of [AlZr₂(PO₄)₄] constructed by PO₄, AlO₄ and ZrO₆ polyhedra interconnected via corner‐sharing O atoms, and one‐dimensional Cs chains which are located in the infinite tunnels within the [AlZr₂(PO₄)₄] framework, which run along the c axis. The Cs, Al, one P and two O atoms lie on a mirror plane, while a second P atom lies on a twofold axis.     

A novel In3O16 fragment in Cs3In3(PO4)4

The double phosphate Cs₃In₃(PO₄)₄, prepared by a flux technique, features a fragment of composition In₃O₁₆ formed by three corner‐sharing InO₆ polyhedra. The central In atom resides on a twofold rotation axis, while the other two In atoms are on general positions. The O atoms in this fragment also belong to PO₄ tetrahedra, which link the structure into an overall three‐dimensional anionic In–O–P network that is penetrated by tunnels running along c. Two independent Cs⁺ cations reside inside the tunnels, one of which sits on a centre of inversion. In general, the organization of the framework is similar to that of K₃In₃(PO₄)₄, which also contains an In₃O₁₆ fragment. However, in the latter case the unit consists of one InO₇ polyhedron and one InO₆ polyhedron sharing an edge, with a third InO₆ octahedron connected via a shared corner. Calculations of the Voronoi–Dirichlet polyhedra of the alkali metals give coordination schemes for Cs of [9+2] and [8+4] ( symmetry), and for K of [8+1], [7+2] and [7+2]. This structural analysis shows that the coordination requirements of the alkali metals residing inside the tunnels cause the difference in the In₃O₁₆ geometry.     

Eine neue Kolorierungsvariante des α‐Mn‐Strukturtyps mit Hauptgruppenelementen in K5Pb24 – Kristallstruktur,Supraleitung und Struktur‐Eigenschafts‐Beziehung

Novel Coloring of the α‐Mn Structure Type with Main Group Elements in K₅Pb₂₄ – Crystal Structure, Superconductivity, and Structure Property Relationship K₅Pb₂₄ was synthesized from the elements in a welded niobium ampoule at 800 °C. The crystal structure was determined from X‐ray single crystal data. Space group I 4 3m, a = 12.358(1) Å, Z = 2, Pearson symbol cI58. The structure of K₅Pb₂₄ shows an ordered atomic distribution on the four crystallographic sites of the α‐Mn structure type. The aristotype is decomposed into cluster units consisting of 48 Pb atoms. The structural subunits are built from four 16‐vertex Frank Kasper polyhedra, which consist of 15 Pb and one K atom (K1). The 16‐vertex polyhedra are centered with another K atom (K2). Four such polyhedra share a common corner (K1) and several edges. 18 shared edges form a truncated tetrahedra of twelve Pb atoms. These atoms form together with four K1 atoms (located in the center of the Frank Kasper polyhedra) a Friauf polyhedra. The result is a ‘supratetrahedra‘ of 48 Pb atoms enclosing five K atoms. The body centered arrangement of this units results in a three‐dimensional framework of Pb atoms. The title compound is the lead‐richest phase of the K/Pb system. Superconducting properties are observed from temperature dependent susceptibility measurements. Field dependent measurements reveal a hard type II superconductor. LMTO and EH band structure calculations verify the metallic behavior. An analysis of the density of states with the help of the electron localization function (ELF) shows the presence of lone pairs in this intermetallic phase. The role of lone pairs is discussed with respect to the superconducting property.     

A layered tin(II) phosphonate, [Sn(C6H5O3P)]n

Poly­[tin(II)‐μ‐phenyl­phospho­nato], [Sn(C₆H₅O₃P)]_n, was synthesized solvothermally at 423 K and crystallized in the monoclinic system, space group Cc. The inorganic layers consist of alternating pyramidal Sn and tetrahedral P centers, joined by doubly bridging O atoms. The corner‐sharing SnO₃ and PO₃C₆H₅ polyhedra define a corrugated layer of six‐membered rings. The layers are connected along the unique b axis by interdigitated phenyl rings of the phenyl­phospho­nate groups.     

A New Type of Anionic Framework in Microporous Potassium Iron(II) Phosphate K[Fe(PO4)]

A new iron(II) orthophosphate K[Fe(PO₄)] has been obtained by hydrothermal synthesis and its crystal structure was determined by single‐crystal X‐ray diffraction: space group P2₁/n, Z = 8, a = 9.6199(10), b = 8.6756(8), c = 10.8996(13) Å, β = 115.577(8)° at 193 K, R = 0.023. Fe^II shows coordination numbers (CN) 4 (distorted tetrahedral) and CN 5 (distorted trigonal bipyramidal). The [FeO₄] and [FeO₅] units form together with the [PO₄] tetrahedra a microporous 3D para‐framework with open channels along the a and b directions. The potassium ions positioned in the channels show CN 7 and 8. The structural relations within the morphotropic row of non‐isotypic K[M(PO₄)] structures (M = Zn, Ni, Mn, Fe) are discussed on the basis of common basic structural units.     

Synthesis,Magnetism, and Crystal Structure of Li2Fe[(PO4)(HPO4)] and its Hydrogen Position Refinement

Lithium iron(III) monophosphate-monohydrogen-monophosphate, Li₂Fe[(PO₄)(HPO₄)], was synthesized under mild hydrothermal conditions and its crystal structure was determined by single crystal X-ray diffraction methods. Crystallographic data: monoclinic, P12₁/n1 (no. 14), a = 4.8142(2) Å, b = 7.9898(4) Å, c = 7.4868(4) Å, β = 104.398(3)°, V = 278.93(2) ų, Z = 2, D_x = 3.104 g · cm^-3. The structure is characterized by FeO₆ octahedra sharing common O-corners with six neighbouring PO₄ tetrahedra to form a three-dimensional framework. Lithium cations are located within channels running along [100]. The channels are formed by eight-membered rings resulting from the connection of alternating FeO₆ octahedra (4×) and phosphate tetrahedra (4×). High-resolution diffraction data allowed to refine a split model for the position of the hydrogen atom. Magnetization data confirm the valence state 3+ for iron and detect an antiferromagnetic ordering of the iron moments below 23.6 K. Thermal decomposition of the compound was investigated by DTA/TG methods.     

A layered fluorinated gallium phosphate organically templated by propane‐1,3‐diaminium,an analog of the aluminophosphate MIL‐12: Ga2(PO4)F5·C3H12N2

Crystals of the oxyfluorinated gallium phosphate MIL‐12 (digallium phosphate penta­fluoride propane‐1,3‐diaminium), (C₃H₁₂N₂)[Ga₂(PO₄)F₅], were synthesized hydro­thermally at 453 K under autogenous pressure using propane‐1,3‐diamine as the structure‐directing agent. The title compound is isomorphous with the aluminium phosphate having the MIL‐12 structural type. The structure is built up from a two‐dimensional anionic network inter­calated by the diamine species. The inorganic layer is composed of corner‐linked GaO₂F₄ octa­hedra and PO₄ tetra­hedra. The diprotonated diamine group is located on a mirror plane, between the inorganic sheets, and inter­acts preferentially via hydrogen bonding through the ammonium groups and the terminal F and bridging O atoms of the inorganic layer. One of the Ga atoms lies on an inversion centre and the other lies on a mirror plane, as does the P atom, two of the phosphate O atoms and one of the F atoms.     

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.     

Solvothermal Syntheses and Structure of a New Polyoxomolybdate Functionalized with Carboxyphosphonate

A new functionalized polyoxomolybdate [(HOOCC₅H₉NCH₂PO₃)₂Mo₅O₁₅]^4– ( 1 ) was synthesized by solvothermal reaction at 120 °C and structurally characterized by X‐ray single‐crystal diffraction, X‐ray powder diffraction as well as with infrared spectroscopy, elemental analysis, and thermogravimetric analysis. The title polyoxoanion consists of a ring of five distorted MoO₆ octahedra linked through four edge‐sharing and one corner‐sharing junctions. Two pending carboxyphosphonate ligands are attached on opposite sides of the ring by the two PO₃ groups. As a result the two dangling arms with their terminal carboxylate groups protrude away from the {Mo₅O₁₅} framework in diametrically opposed directions. Each Mo₅‐ring is further connected to adjacent Mo₅‐ring through hydrogen bonds, which consist in the protonated nitrogen atoms, the carboxyl oxygen atoms from L^3– ligands and oxygen atoms from {Mo₅O₁₅} cluster to form a 2D framework structure.     

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.     

New Structure Type among Octahydrated Rare‐Earth Sulfates, β‐Ce2(SO4)3·8H2O,and a new Ce2(SO4)3·4H2O Polymorph

Syntheses, crystal structures and thermal behavior of two new hydrated cerium(III) sulfates are reported, Ce₂(SO₄)₃·4H₂O ( I ) and β‐Ce₂(SO₄)₃·8H₂O ( II ), both forming three‐dimensional networks. Compound I crystallizes in the space group P2₁/n. There are two non‐equivalent cerium atoms in the structure of I , one nine‐ and one ten‐fold coordinated to oxygen atoms. The cerium polyhedra are edge sharing, forming helically propagating chains, held together by sulfate groups. The structure is compact, all the sulfate groups are edge‐sharing with cerium polyhedra and one third of the oxygen atoms, belonging to sulfate groups, are in the S–Oμ₃–Ce₂ bonding mode. Compound II constitutes a new structure type among the octahydrated rare‐earth sulfates which belongs to the space group Pn. Each cerium atom is in contact with nine oxygen atoms, these belong to four water molecules, three corner sharing and one edge sharing sulfate groups. The crystal structure is built up by layers of [Ce(H₂O)₄(SO₄)]_nⁿ⁺ held together by doubly edge sharing sulfate groups. The dehydration of II is a three step process, forming Ce₂(SO₄)₃·5H₂O, Ce₂(SO₄)₃·4H₂O and Ce₂(SO₄)₃, respectively. During the oxidative decomposition of the anhydrous form, Ce₂(SO₄)₃, into the final product CeO₂, small amount of CeO(SO₄) as an intermediate species was detected.     

Mn3(OAc)6·CH3CN: a porous dehydrated manganese(II) acetate

The crystal structure of a new form of dehydrated manganese(II) acetate, poly[[hexa‐μ₃‐acetato‐trimanganese(II)] acetonitrile solvate], {[Mn₃(CH₃COO)₆]·CH₃CN}_n, (I), reveals a three‐dimensional polymeric structure based on an {Mn₃} trimer. The {Mn₃} asymmetric unit contains three crystallographically independent Mn positions, comprising a seven‐coordinate center sharing a mirror plane with a six‐coordinate center, and another six‐coordinate atom located on an inversion center. Two of the four crystallographically independent acetate (OAc) ligands, as well as the acetonitrile solvent molecule, are also located on the mirror plane. The Mn atoms are connected by a mixture of Mn—O—Mn and Mn—OCO—Mn bridging modes, giving rise to face‐ and corner‐sharing interactions between manganese polyhedra within the trimers, and edge‐ and corner‐sharing connections between the trimers. The network contains substantial pores which are tightly filled by crystallographically located acetonitrile molecules. This structure represents the first porous structurally characterized phase of anhydrous manganese(II) acetate and as such it is compared with the closely related densely packed anhydrous manganese(II) acetate phase, solvent‐free β‐Mn(OAc)₂.     

The triple pyrophosphate Cs3CaFe(P2O7)2

The complex phosphate tricaesium calcium iron bis(diphosphate), Cs₃CaFe(P₂O₇)₂, has been prepared by the flux method. Isolated [FeO₅] and [CaO₆] polyhedra are linked by two types of P₂O₇ groups into a three‐dimensional framework. The latter is penetrated by hexagonal channels along the a axis where three Cs atoms are located. Calculations of caesium Voronoi–Dirichlet polyhedra give coordination schemes for the three Cs atoms as [8 + 3], [9 + 1] and [9 + 4]. The structure includes features of both two‐ and three‐dimensional frameworks of caesium double pyrophosphates.     

Structure and 31P NMR spectroscopy of a new phosphate,Na8Ca1.5Mg12.5(PO4)12

A new phosphate, sodium calcium magnesium tetrakis(phosphate), Na₈Ca_1.5Mg_12.5(PO₄)₁₂, has been synthesized by a flux method. Its novel structure consists of MgO_x (x = 5 and 6) polyhedra and MO₇ (M = Mg or Na) octahedra linked directly through common corners or edges to form a rigid three‐dimensional skeleton, reinforced by corner‐sharing between identical Mg₁₂MO₄₈ units. The connection of these units by the PO₄ tetrahedra induces cavities and crossing tunnels where the Na⁺ and Ca²⁺ cations are located. This structural model was supported by a ³¹P NMR spectroscopy study which confirmed the existence of 12 crystallographically independent sites for the P atoms.     

Sodium magnesium bis(vanadate) pyrovanadate: Na6Mg2(VO4)2(V2O7)

The crystal structure of the new complex vanadium oxide Na₆Mg₂(VO₄)₂(V₂O₇) was solved from X‐ray single‐crystal data. The structure contains VO₄ tetrahedra and MgO₆ octahedra, linked by corners and forming a complex three‐dimensional framework. A half of the VO₄ tetrahedra are connected only to MgO₆ octahedra, whereas the others are corner‐sharing, forming V₂O₇ pyrovanadate groups with statistically random orientations. One unique Mg atom is located at an inversion centre, while the other Mg atom, one unique V atom and five unique O atoms lie on mirror planes.     

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.