Chains Of Edge-sharing Octahedra Research Articles

Structural Variations in Manganese Halide Chain Compounds Mediated by Methylimidazolium Isomers

The structures of two new hybrid organic–inorganic manganese halide compounds [1MiH]MnCl3(H2O) and [4MiH]MnCl3(H2O) ([1MiH] = 1-methylimidazolium, [4MiH] = 4-methylimidazolium) have been determined by single crystal X-ray diffraction. Both are composed of one dimensional [MnCl3(H2O)]n− edge-sharing octahedral chains. The structures are compared to the previously reported isomeric analogue [2MiH]MnCl3(H2O) ([2MiH] = 2-methylimidazolium), and three closely related compounds. The variations in packing of the inorganic chains are shown to be influenced by hydrogen bonding abilities of the imidazolium or related moieties. Both new compounds show intense red luminescence at ambient temperature under UV irradiation.

Three New Lead Iodide Chain Compounds, APbI3, Templated by Molecular Cations

The crystal structures of three new hybrid organic-inorganic lead halide compounds [IqH]PbI3, [4MiH]PbI3, and [BzH]PbI3 ([IqH+] = isoquinolinium, [4MiH+] = 4-methylimidazolium, [BzH+] = benzotriazolium) have been determined by single crystal x-ray diffraction. All three compounds have the same generic formula as perovskite, ABX3, but adopt a rare non-perovskite structure built from one dimensional (1D) edge-sharing octahedral chains. The bandgap of each compound was investigated by solid UV-Vis spectra. In comparison with previously reported hybrid compounds containing the same type of octahedral chains, [C10H7CH2NH3]Pbl3 and (C7H7N2)PbI3, all three new compounds have lower bandgaps (<2.4 ev), indicating that they may be promising for photovoltaic application.

Mono- and Mixed-Valence Tetrathiafulvalene Semiconductors (TTF)BiI4 and (TTF)4BiI6 with 1D and 0D Bismuth-Iodide Networks.

Two new compounds containing tetrathiafulvalene (TTF) cations with extended and discrete anions based on Bi and I are reported. The compound (TTF)BiI4 comprises [BiI2I4/2]- chains of edge-shared octahedra that are interspersed with stacks of TTF+•. The compound (TTF)4BiI6 has mixed-valence stacks of TTF and TTF+• and discrete molecules of TTF+• separated by discrete [BiI6]-3 anions. The optical and electrical transport properties of these compounds are reported. Due to the mixed-valence stacks of TTF, (TTF)4BiI6 is the significantly better electrical conductor than (TTF)BiI4, despite the discrete nature of the inorganic moiety.

Transformation of kyanite to andalusite in the Benamocarra Unit (Betic Cordillera, S. Spain). Kinetics and petrological significance

Kyanite is directly replaced by andalusite in quartz–plagioclase veins included within graphite-bearing micaschists of the Alpine Benamocarra Unit (Betic Cordillera, Spain). Electron back-scattered diffraction indicates that: i) precursory kyanite contains planar defects; ii) andalusite growth was crystallographically controlled by the kyanite; and iii) the structure of both Al2SiO5 phases shares nearly the closest-packed oxygen array and chains of edge-sharing octahedra. The small entropy difference of the kyanite–andalusite polymorphic inversion makes it difficult to overcome the energy barrier of this transformation. The driving force needed for the kyanite-to-andalusite reaction was a temperature ( T ) increase during a pre-Alpine tectonometamorphic evolution. The low- P /medium- T metamorphic conditions that affected the rocks studied took place in relation to a late Variscan extensional collapse. The reaction pathway proposed here corresponds to the first part of a poly-orogenic tectonometamorphic evolution, consisting of a pre-Alpine metamorphism of high thermal gradient with mainly static growth of porphyroblasts, followed by an essentially dynamic metamorphism during the Alpine orogeny.

Flurlite, Zn3Mn2+Fe3+(PO4)3(OH)2·9H2O, a new mineral from the Hagendorf Süd pegmatite, Bavaria, with a schoonerite-related structure

AbstractFlurlite, ideally Zn3Mn2+Fe3+(PO4)3(OH)2·9H2O, is a new mineral from the Hagendorf-Süd pegmatite, Hagendorf, Oberpfalz, Bavaria, Germany. Flurlite occurs as ultrathin (<1 μm) translucent platelets that form characteristic twisted accordion-like aggregates. The colour varies from bright orange red to dark maroon red. Cleavage is perfect parallel to (001). The mineral occurs on mitridatite and is closely associated with plimerite. Other associated minerals are beraunite, schoonerite, parascholzite, robertsite and altered phosphophyllite. The calculated density of flurlite is 2.84 g cm–3. It is optically biaxial (–), α = 1.60(1), β= 1.65(1) and γ = 1.68(1), with weak dispersion and parallel extinction, X ≈ c, Y ≈ a, Z ≈ b. Pleochroism is weak, with colours: X = pale yellow, Y = pale orange, Z = orange brown. Electron microprobe analyses (average of seven) with FeO and Fe2O3 apportioned and H2O calculated on structural grounds, gave ZnO 25.4, MnO 5.28, MgO 0.52, FeO 7.40, Fe2O3 10.3, P2O5 27.2, H2O 23.1, total 99.2 wt.%. The empirical formula, based on 3 P a.p.f.u. is Zn2.5Mn2+0.6Fe2+0.8Mg0.1Fe3+(PO4)3(OH)2·9H2O. Flurlite is monoclinic, P21/m, with the unit-cell parameters (at 100 K) of a = 6.3710(13), b = 11.020(2), c = 13.016(3) Å, β = 99.34 (3)°. The strongest lines in the X-ray powder diffraction pattern are [dobs in Å(I) (hkl)] 12.900(100)(001); 8.375(10)(011); 6.072(14)(101); 5.567(8)(012); 4.297(21)(003); 2.763(35)(040). Flurlite (R1 = 0.057 for 995 F > 4σ(F)) has a heteropolyhedral layer structure, with layers parallel to (001) and with water molecules packing between the layers. The slab-like layers contain two types of polyhedral chains running parallel to [100]: (a) chains of edge-sharing octahedra containing predominantly Zn and (b) chains in which Fe3+-centred octahedra share their apices with dimers comprising Zn-centred trigonal bipyramids sharing an edge with PO4 tetrahedra. The two types of chains are interconnected by corner-sharing along [010]. A second type of PO4 tetrahedron connects the chains to MnO2(H2O)4 octahedra along [010] to complete the structure of the (001) slabs. Flurlite has the same stoichiometry as schoonerite, but with dominant Zn rather than Fe2+ in the edge-shared chains. Schoonerite has a similar heteropolyhedral layer structure with the same layer dimensions 6.4 × 11.1 Å. The different symmetry (orthorhombic, Pmab) for schoonerite reflects a different topology of the layers.

Antisymmetric Spin-Orbit Coupling in a d-p Model on a Zigzag Chain

We theoretically investigate how an antisymmetric spin-orbit coupling emerges in electrons moving on lattice structures which are centrosymmetric but break the spatial inversion symme- try at atomic positions. We construct an effective d-p model on the simplest lattice structure, a zigzag chain of edge-sharing octahedra, with taking into account the crystalline electric field, the spin-orbit coupling, and on-site and inter-site d-p hybridizations. We show that an effective antisymmetric spin-orbit coupling arises in the sublattice-dependent form, which results in a hidden spin polarization in the band structure. We explicitly derive the effective antisymmetric spin-orbit coupling for d electrons, which not only explains the hidden spin polarization but also indicates how to enhance it.

The crystal chemistry of iron (III) monophosphates with mono and divalent metallic cations

As a contribution to the study of alkaline iron (III) monophosphates, we recently investigated the A 3 PO 4 -M 3 (PO 4 ) 2 -FePO 4 (A: alkali metal; M: divalent cation) using both the flux method and the solid state reaction. This investigation led to the synthesis and structural characterization of twelve new compounds. Their structural analysis showed them to be constructed by PO 4 tetrahedra and FeO x polyhedra (x = 6, 5, 4). The Fe polyhedra are either isolated or forming finite units of corner- or edge-sharing, or infinite chains of edge-sharing octahedra. The resulting Fe structural units are linked by the PO 4 tetrahedra via corner or edge-sharing, giving rise to mixed covalent frameworks which can be either bi- or three-dimentionnel. The alkali cations occupy the interlayer space or tunnels and cavities.

Crystal structure of a new high-pressure polymorph of topaz-OH

A new high-pressure form of topaz-OH (denoted here topaz-OH II) was obtained at 14 GPa and 1400 °C. The X-ray diffraction pattern of this phase can be indexed by an orthorhombic cell with a = 4.72318(5), b = 8.91480(9), and c = 2.77276(3) A. The lengths of a and b are similar, but c is approximately a third of that for a previously reported topaz-OH (denoted topaz-OH I). The structural formula of topaz-OH II can be written as (Al 0.68 Si 0.32 )(O 0.66 (OH) 0.34 ) 2 , suggesting significant cation disorder in the structure. The crystal structure of topaz-OH II is solved using powder synchrotron X-ray diffraction data, and refined with constraints provided by a separate multi-nuclear NMR study. The structure has similarities with topaz-OH I and diaspore (α-AlOOH) structures, having partially occupied double edge-shared octahedral chains, and 2 × 1 tunnels with partially occupied tetrahedral and octahedral sites.

Synthesis, Structure and Magnetic Phase Transitions of the Manganese Succinate Hybrid Framework, Mn(C4H4O4)

An anhydrous manganese succinate, Mn(C(4)H(4)O(4)), has been synthesised hydrothermally and studied by single-crystal X-ray diffraction. It adopts a succinate pillared structure in which layers of corner-sharing MnO(6) octahedra alternate with sheets that contain chains of edge-sharing octahedra. This unique 3D framework structure contains highly distorted MnO(6) octahedra, which are made possible by the lack of ligand field stabilisation energy for the high-spin Mn(2+) ion. Attempts to dope the structure with other divalent transition-metal ions were accordingly unsuccessful. Magnetic susceptibility and heat capacity measurements indicate that Mn(C(4)H(4)O(4)) undergoes antiferromagnetic ordering below 12 K, with a second antiferromagnetic transition at approximately 6 K. These two antiferromagnetic phases undergo further transitions in applied fields, underlining the subtle magnetic behaviour that is possible in inorganic-organic frameworks of this structural complexity.

Structure and Physical Properties of New Iron Hydrogenophosphates: K2Fe(HP2O7)(H2PO4)2, LiH3Fe2(P2O7)2, and FeH2P2O7

The exploration of the systems Fe-H-P-O, Li-Fe-H-P-O, and K-Fe-H-P-O using soft chemistry methods has allowed three new hydrogenophosphates to be synthesized, whose structures have been determined by ab initio calculations. The structures of two of them--FeH(2)P(2)O(7) and LiH(3)Fe(P(2)O(7))(2)--exhibit close relationships: their 3D framework consists of [FeO(4)](infinity) and [LiFe(2)O(12)](infinity) chains of edge-sharing octahedra, respectively, interconnected through diphosphate groups. These two diphosphates exhibit a paramagnetic to antiferromagnetic transition at low temperatures. The former phase exhibits intrachain ferromagnetic interactions (theta(p) > 0) in competition with the antiferromagnetic interchain ordering, whereas for the second one, the ferromagnetic interactions have disappeared due to the presence of Li in the chains. Differently, the third phosphate, K(2)Fe(HP(2)O(7))(H(2)PO(4))(2), exhibits a chain structure, involving isolated FeO(6) octahedra, and consequently is paramagnetic in the whole temperature range (4-300 K). Among these three phosphates, only the latter exhibits ionic conductivity, which may originate from the proton mobility.

Crystal supramolecularity of polymeric and monomeric organic–inorganic hybrid complexes containing 2,5-dibromopyridinium Cd(II)-chloride

Crystal structure determinations of the complexes (C5H4Br2N)2[CdCl4].H2O and {[C5H4Br2N][Cd(OH2)Cl-μ-Cl2]} n , (henceforth 1 and 2, respectively), have been determined. In the monomeric anion of 1, the geometry around Cd is distorted tetrahedral whereas in the polymeric anion 2, the coordination around Cd is distorted octahedral with a zig-zag chain of edge-sharing octahedra along b, that are connected via short intra H[sbnd]O[sbnd]H [bdot] Cl[sbnd]Cd hydrogen bonds. There are many intermolecular interactions between the cations and anions (some are extremely short) of the types O[sbnd]H [bdot] Cl, C[sbnd]Br [bdot] Cl[sbnd]Cd, N[sbnd]H [bdot] Cl and aryl [bdot] aryl (π [bdot] π), leading to a three-dimensional network.

Ternary Erbium Chromium Sulfides: Structural Relationships and Magnetic Properties

Single crystals of four erbium-chromium sulfides have been grown by chemical vapor transport using iodine as the transporting agent. Single-crystal X-ray diffraction reveals that in Er(3)CrS(6) octahedral sites are occupied exclusively by Cr(3+) cations, leading to one-dimensional CrS(4)(5-) chains of edge-sharing octahedra, while in Er(2)CrS(4), Er(3+), and Cr(2+) cations occupy the available octahedral sites in an ordered manner. By contrast, in Er(6)Cr(2)S(11) and Er(4)CrS(7), Er(3+) and Cr(2+) ions are disordered over the octahedral sites. In Er(2)CrS(4), Er(6)Cr(2)S(11), and Er(4)CrS(7), the network of octahedra generates an anionic framework constructed from M(2)S(5) slabs of varying thickness, linked by one-dimensional octahedral chains. This suggests that these three phases belong to a series in which the anionic framework may be described by the general formula [M(2n+1)S(4n+3)](x-), with charge balancing provided by Er(3+) cations located in sites of high-coordination number within one-dimensional channels defined by the framework. Er(4)CrS(7), Er(6)Cr(2)S(11), and Er(2)CrS(4) may thus be considered as the n = 1, 2, and infinity members of this series. While Er(4)CrS(7) is paramagnetic, successive magnetic transitions associated with ordering of the chromium and erbium sub-lattices are observed on cooling Er(3)CrS(6) (T(C)(Cr) = 30 K; T(C)(Er) = 11 K) and Er(2)CrS(4) (T(N)(Cr) = 42 K, T(N)(Er) = 10 K) whereas Er(6)Cr(2)S(11) exhibits ordering of the chromium sub-lattice only (T(N) = 11.4 K).

Crystal structure of glaucodot, (Co,Fe)AsS, and its relationships to marcasite and arsenopyrite

The crystal structure of glaucodot, (Co,Fe)AsS, an important member of the FeAsS-CoAsS-NiAsS system, was determined with single-crystal X-ray diffraction. It is orthorhombic with space group Pn21m and unit-cell parameters a = 14.158(1), b = 5.6462(4), c = 3.3196(2) A, and V = 265.37(5) A 3 . The structure is closely related to that of arsenopyrite or alloclasite, and represents a new derivative of the marcasite-type structure. The As and S atoms in glaucodot, which are ordered into six distinct sites (As1, As2, As3, S1, S2, and S3), form three types of layers [S, As, and mixed (S + As) layers] that are stacked along a in the sequence of (S + As)-(S + As)-S-(S + As)-(S + As)-As-(S + As)-(S + As)... In contrast, arsenopyrite contains the mixed (S + As) layers only and alloclasite consists of isolated S and As layers only. There are no As-As or S-S bonds in glaucodot; all dianion units are formed between S and As, like those in arsenopyrite and alloclasite. The (Co + Fe) cations in glaucodot occupy three nonequivalent octahedral sites (M1, M2, and M3), with M1(As5S), M2(As3S3), and M3(AsS5), which form three distinct edge-shared octahedral chains, A, B, and C, parallel to c, respectively. These chains are arranged along a in the sequence of A-A-B-C-C-B-A-A.... Whereas the configurations of the A and C chains are analogous to those in safflorite and marcasite, respectively, the configuration of the B chain matches that in alloclasite, leading us to propose that the M1, M2, and M3 sites are predominately occupied by Co, (Co + Fe), and Fe, respectively. Our study, together with previous observations, suggests that glaucodot is likely to have an ideal stoichiometry of (Co0.5Fe0.5)AsS, with a limited tolerance for the variation of the Co/Fe ratio.

Three Dimensional Network Polymeric Structure of (4,4′-bipyridinium)[CdBr4] n : Supramolecular Motifs and Crystal Supramolecularity

A single crystal structure determination of the complex (4,4′-bipyridinium)[CdBr4] n , [henceforth (I)], has been carried out. It crystallizes in the monoclinic space group C2/c, with the following cell parameters: a = 16.119(3) A, b = 13.206(3) A, c = 7.2601(15) A, β = 115.62°, V = 1393.5(6) A3, with Z = 4 formula units. The polymeric anion forms an infinite zig-zag chain of edge-sharing octahedra along c, with a distorted octahedral stereochemistry around Cd. There are N–H···Br [Br2···N1 of 3.386(13) A and Br1···N1 of 3.363(13) A] and C–H···Br [Br2···C5 of 3.552(16) A] hydrogen bonding interactions, tying the CdBr chains to the cations to form 2D-network. The resulting 2D-networks are further linked by aryl···aryl (π···π) interactions within the cationic chains leading to a 3D-network. Three dimensional network polymeric structure of (4,4′-bipyridinium)[CdBr4] n : Supramolecular motifs and crystal supramolecularity. Rawhi Al-Far and Basem F. Ali The polymeric anion consists of a zig–zag chain of distorted edge shared octahedra run along c axis. The protonated cation bridges the anion chains through N–H···Br and C–H···Br into a supramolecular array.

Two packing motifs based upon chains of edge-sharing PbI6octahedra

The compounds catena-poly[p-phenylenediammonium [[diiodolead(II)]-di-mu-iodo] dihydrate], {(C6H10N2)[PbI4].2H2O}n, (I), and catena-poly[bis(3,5-dimethylanilinium) [[diiodolead(II)]-di-mu-iodo]], {(C8H12N)2[PbI4]}n, (II), crystallize as organic-inorganic hybrids. As such, the structures consist of chains of [PbI2]- units extending along the c axis in (I) and along the b axis in (II). The asymmetric unit in (I) contains one Pb atom on a site of 2/m symmetry, two I atoms and a water molecule on mirror planes, and a p-phenylenediammonium molecule that sits around a site of 2/m symmetry with the C and N atoms on a mirror plane. In (II), the Pb atom is on a twofold axis and the two I atoms are on general positions. Each Pb atom is octahedrally coordinated to six I atoms, arranged as chains of edge-sharing octahedra. Both compounds undergo hydrogen-bonding interactions between the ammonium groups and the I atoms. In addition, there are hydrogen bonds between the water molecules and the ammonium groups and halides in (I), and between the ammonium groups and the ring systems in (II).

Poppiite, the V3+ end-member of the pumpellyite group: Description and crystal structure

Poppiite, a new mineral from Gambatesa mine (Val Graveglia, Genova, Northern Italy), is the V 3+ end-member of the pumpellyite group [ [VII] (Ca 7.68 Na 0.27 K 0.03 Rb 0.02 ) ∑8.00 [VI] (V 3+ 1.26 Fe 3+ 1.02 Mg 0.78 Mn 2+ 0.59 Al 0.31 Cu 2+ 0.04 ) ∑4.00 [VI] (V 3+ 6.89 Al 1.07 Ti 0.04 ) ∑8.00 [IV] (Si 11.69 Al 0.31 ) ∑12.00 O 42 (OH) 14 ; C 2/ m , a = 19.2889(6), b = 6.0444(2), c = 8.8783(3) A, β = 97.328(2)° , V = 1026.66(6) A 3 , D meas = 3.36(2) g/cm 3 , and D calc = 3.44 g/cm 3 ]. Poppiite crystals, with size varying from 0.1 to 0.6 mm, are minute, greenish-brown, and prismatic, and are associated with roscoelite, ganophyllite, manganaxinite, goldmanite, and calcite. The strongest lines in the X-ray powder diffraction pattern [ d obs (A), I rel , ( hkl )] are: 2.930, 100, (511); 3.817, 70, (202); 2.548, 65, (313); 2.551, 62, (420); 1.612, 57, (731,424); and 2.367, 51, (222, 403). Poppiite is optically negative, with 2 V calc = 44°, n α = 1.768(9), n β 1.804(8), n γ 1.810(9). The pleochroic scheme is α = light yellowish brown, β = deep greenish brown, and γ = brown to reddish brown. The crystal structure was refined using 1918 unique reflections to R = 0.0307. Like the other pumpellyite-group minerals the crystal structure of poppiite consists of chains of edge-sharing octahedra linked by SiO 4 , Si 2 O 7 , and CaO 7 polyhedra.

Synthesis and ab initio structural determination of a new pillared nickel diphosphonate: VSB-6 or Ni 5.4(OH,F) 4[O 3P(CH 2) 3PO 3] 2(H 2O) 1.4·1.2H 3O

Ni 5.4(OH,F) 4[O 3P(CH 2) 3PO 3] 2(H 2O) 1.4·1.2H 3O or VSB-6 was prepared under hydrothermal conditions (4–6 days, 180 °C, autogenous pressure). It was structurally characterized, ab initio, from laboratory X-ray powder diffraction data: orthorhombic, space group Pmmn (n ∘59), a=17.937(1), b=6.4299(4), c=4.4936(3) Å, V=518.27(4) Å 3, D c=2.694 g·cm −3. The structure is built up from inorganic layers, Ni 5.4(OH,F) 4O 12P 4(H 2O) 1.4, constructed from chains of edge-sharing octahedra onto which are grafted phosphonate groups and statistically occupied nickel octahedra. The alkyl chain of the organic moiety connects the inorganic layers to form a pillared solid. VSB-6 is stable under air up to 400 °C. On cooling to 6 K, VSB-6 orders magnetically with a canted antiferromagnetic structure.

Preparation and Crystal Structures of Mg(NH3)2Cl2, Mg(NH3)2Br2, and Mg(NH3)2I2

Diammine magnesium halides Mg(NH3)2X2 with X=Cl, Br, I have been prepared from magnesium metal and the corresponding ammonium halide in steel autoclaves at 350°C. Mg(NH3)2Cl2 crystallizes in the Cd (NH3)2Cl2-structure type: Rietveld X-ray analysis, Cmmm, Z=2; a=8.1810(2) Å, b=8.2067(2) Å, c=3.7550(1) Å, R(F2)Bragg=5.9%. The bromide and the iodide are isotypic and crystallize in a new structure type: single crystal X-ray analysis, Pbam, Z=2; Mg(NH3)2Br2: a=5.944(2) Å, b=11.876(3) Å, c=3.983(1) Å, R1 (F)=0.045; Mg(NH3)2I2: a=6.285(1) Å, b=12.559 (3) Å, c=4.302(1) Å, R1(F)=0.080. Both structure types contain chains of edge-sharing octahedra 1∞[MgX4/2(NH3)2] running along c. These are arranged in different ways relative to one another in the two structure types.

Synthesis and Characterization of a Series of Quaternary Chalcogenides BaLnMQ3 (Ln=Rare Earth, M=Coinage Metal, Q=Se or Te)

The compounds BaGdAuSe3, BaLaCuTe3, BaYCuTe3, BaYAgTe3, BaLaAgTe3, BaYbCuTe3, BaGdAgTe3, BaNdCuTe3, and BaPrCuTe3 were prepared by the reaction in a BaBr2/KBr flux at 850°C of a rare earth, a coinage-group metal, a chalcogen, and BaSe or BaTe. The unit cells of all of the compounds and the crystal structures of the first four compounds were determined by single-crystal X-ray diffraction methods. With the exception of BaLaCuTe3, which crystallizes with four formula units in the orthorhombic space group Pnma, all of these compounds crystallize with four formula units in the orthorhombic space group Cmcm. BaLaCuTe3, isostructural with β-BaLaCuSe3 and Eu2CuS3 (i.e., Eu2+Eu3+Cu+(S2−)3), and BaGdAuSe3, BaYCuTe3, and BaYAgTe3, isostructural with KZrCuS3, crystallize in a layered structure in which there are 2∞[LnMQ2−3] layers separated by Ba2+ ions. Ln atoms are coordinated by six Q atoms at the corners of a distorted octahedron, and M atoms are coordinated by four Q atoms at the corners of a tetrahedron. The layers are formed by the connection of edge-sharing octahedral chains and corner-sharing tetrahedral chains. Ba atoms are coordinated by seven Q atoms in BaLaCuTe3 and by eight Q atoms in BaGdAuSe3, BaYCuTe3, and BaYAgTe3. BaNdAgTe3 shows temperature-dependent paramagnetism. Its magnetic susceptibility follows the Curie–Weiss law. The effective magnetic moment of 3.4(3) μB is in agreement with the theoretical value of 3.6 μB for Nd3+.

Hydrothermal synthesis, crystal structure and thermal transformation of a new zinc arsenate hydrate, Zn9(AsO4)6·4H2O †

A new synthetic polymorph of zinc arsenate hydrate, Zn9(AsO4)6·4H2O, was prepared from an aqueous solution. Owing to the small size of the crystals, synchrotron X-ray radiation was applied for the indexing and data collection. An initial structural model was found from 1819 unique reflections measured (space group P, refined to wR = 0.154, R = 0.060). Optimisation of the synthesis conditions provided larger crystals for crystallographic measurements using a conventional diffractometer: a = 6.6895(3), b = 9.1761(4), c = 10.1377(8) Å, α = 69.428(5), β = 77.205(5), γ = 75.765(4)°, space group P. The structure was refined to wR = 0.072, R = 0.061. The crystal structure of Zn9(AsO4)6·4H2O is built from chains of edge-sharing octahedra and trigonal-bipyramidal Zn atoms co-ordinated to framework oxygen and water molecule oxygen atoms. These chains are connected by tetrahedra of Zn and As co-ordinated to framework oxygen atoms. Channels run along the a axis where the water molecules are placed. The compound transforms into a new phase of Zn3(AsO4)2 at 424(1) °C and into the known phase β-Zn3(AsO4)2 at 865(1) °C.