Single-crystal characterization of Co7(OH)6(H2O)3(C4H4O4)47H2O; A new cobalt succinate identified through high-throughput synthesis

A new form of cobalt succinate has been discovered using high-throughput methods and its structure was solved by single crystal X-ray diffraction. Co₇(C₄H₄O₄)₄(OH)₆(H₂O)₃7H₂O crystallizes in the monoclinic space group P2₁/c with cell parameters: a=7.888(2) Å, b=19.082(6) Å, c=23.630(7) Å, β=91.700(5)°, V=3555(2) Å³, R₁=0.0469. This complex structure, containing 55 crystallographically distinct non-hydrogen atoms, is compared to the previously reported nickel phase, characterized using ab initio structure solution from synchrotron powder diffraction data.     

Syntheses and characterization of Co(pydc)(H2O)2 and Ni(pydc)(H2O) (pydc = 3,5-pyridinedicarboxylate)

The hydrothermal reaction of 3,5-pyridinedicarboxylic acid (pydcH₂) and Co(NO₃)₂ or Ni(NO₃)₂ in the presence of 4,4′-bipyridine results in two novel compounds Co(pydc)(H₂O)₂ (1) and Ni(pydc)(H₂O) (2). Crystal data: 1, monoclinic, C2/c, a=9.900(2), b=11.984(2), c=7.3748(15) Å, β=105.37(3)°, V=843.7(3) Å³, Z=4; 2, monoclinic, P2₁/c, a=7.7496(6), b=15.0496(11), c=6.4224(5) Å, β=108.437(1)°, V=710.59(9) Å³, Z=4. The structure of 1 is composed of honeycomb layers built up from {CoO₄N} trigonal bipyramids and 3,5-pyridinedicarboxylate bridges. The structure of 2 adopts a three-dimensional framework structure in which the Ni atoms are coordinated by the pydc bridges both within the honeycomb layer and between the layers. The magnetic properties of 1 and 2 have been investigated.     

Novel M(II)–Hg(II) coordination polymers generated from metal-containing building blocks M(2-pyrazinecarboxylate)2 · (H2O)2 (M=Cu, Ni, Co) and HgCl2

A new class of M(II)–Hg(II) (M=Cu(II), Co(II), Ni(II)) mixed-metal coordination polymers, Cu(2-pyrazinecarboxylate)₂HgCl₂ (4), [Co(2-pyrazinecarboxylate)₂(HgCl₂)₂] · 0.61H₂O (5) and [Ni(2-pyrazinecarboxylate)₂(HgCl₂)₂] · 0.77H₂O (6), have been prepared by self assembly of metal-containing building blocks, M(2-pyrazinecarboxylate)₂ · (H₂O)₂(M=Cu(II), Co(II), Ni(II)), with HgCl₂. Compounds 4–6 were characterized fully by IR, elemental analysis and single crystal X-ray diffraction. Compound 4 crystallized in the monoclinic space group C2/c, with a=17.916(5) Å, b=7.223(2) Å, c=13.335(4) Å, β=128.726(3)°, V=1346.2(6) ų, Z=4. It contains alternating Hg(II) and Cu(II) metal centers that are cross-linked by 2-pyrazinecarboxylate spacers and chlorine co-ligands to generate a unique three-dimensional Hg(II)–Cu(II) mixed metal framework. Compound 5 crystallized in the triclinic space group P , with a=6.3879(7) Å, b=6.6626(8) Å, c=13.2286(15) Å, α=96.339(2)°, β=91.590(2)°, γ=113.462(2)°, V=511.71(10) ų, Z=1. Compound 6 also crystallized in the triclinic space group P , with a=6.3543(8) Å, b=6.6194(8) Å, c=13.2801(16) Å, α=96.449(2)°, β=92.263(2)°, γ=113.541(2)°, V=506.67(11) ų, Z=1. Compounds 5 and 6 are isostructural and in the solid state the Hg(II)M(II)Hg(II) units are connected by Hg₂Cl₂ linkages to produce a novel M(II)–Hg(II) (M=Co(II), Ni(II)) zigzag mixed-metal chain, in which a new type of M–M′–M′–M array was observed. The metal containing building blocks, M(2-pyrazinecarboxylate)₂ · (H₂O)₂ (M=Cu(II), Co(II), Ni(II)), exhibit different connectivities to HgCl₂ depending on the metal cation contained within them.     

Synthesis and characterization of [Zn(2,2′-bipy)]2(H2PO3)4: A neutral zinc phosphite cluster containing ZnO3N2 and H2PO3 units

The hydrothermal synthesis, crystal structure and some properties of a zinc phosphite with a neutral cluster, [Zn(2,2′-bipy)]₂(H₂PO₃)₄, are reported. This compound crystallizes in the triclinic system of space group P-1 (No. 2), a=8.3067(5) Å, b=8.9545(4) Å, c=10.0893(6) Å, α=95.448(2)°, β=99.7530(10)°, γ=103.461(2)°, V=712.23(7) ų, Z=1. The cluster consists of 4-membered rings formed by alternating ZnO₃N₂ square pyramids and H₂PO₃ pseudo pyramids, with two “hanging” H₂PO₃ groups attached to each of the Zn centers. The clusters are linked together by extensive multipoint hydrogen bonding involving the phosphite units to form a sheet-like structure. This compound represents the first example of zinc phosphite with P---OH bonds. An intense photoluminescence was observed from this compound upon photoexcitation at 388 nm.     

Syntheses, crystal structures and spectroscopic properties of KEu[AsS4], K3Dy[AsS4]2 and Rb4Nd0.67[AsS4]2

Three rare earth compounds, KEu[AsS₄] (1), K₃Dy[AsS₄]₂ (2), and Rb₄Nd_0.67[AsS₄]₂ (3) have been synthesized employing the molten flux method. The reactions of A₂S₃ (A = K, Rb), Ln (Ln = Eu, Dy, Nd), As₂S₃, S were accomplished at 600 °C for 96 h in evacuated fused silica ampoules. Crystal data for these compounds are: 1, monoclinic, space group P2₁/m (no. 11), a = 6.7276(7) Å, b = 6.7190(5) Å, c = 8.6947(9) Å, β = 107.287(12)°, Z = 2; 2, monoclinic, space group C2/c (no. 15), a = 10.3381(7) Å, b = 18.7439(12) Å, c = 8.8185(6) Å, β = 117.060(7)°, Z = 4; 3, orthorhombic, space group Ibam (no. 72), a = 18.7333(15) Å, b = 9.1461(5) Å, c = 10.2060(6) Å, Z = 4. 1 is a two-dimensional structure with ²_∞[Eu(AsS₄)]⁻ layers separated by potassium cations. Within each layer, distorted bicapped trigonal [EuS₈] prisms are linked through distorted [AsS₄]³⁻ tetrahedra. Each Eu²⁺ cation is coordinated by two [AsS₄]³⁻ units by edge-sharing and bonded to further two [AsS₄]³⁻ units by corner-sharing. Compound 2 contains a one-dimensional structure with ¹_∞[Dy(AsS₄)₂]³⁻ chains separated by potassium cations. Within each chain, distorted bicapped trigonal prisms of [DyS₈] are linked by slightly distorted [AsS₄]³⁻ tetrahedra. Each Dy³⁺ ion is surrounded by four [AsS₄]³⁻ moieties in an edge-sharing fashion. For compound 3 also a one-dimensional structure with ¹_∞[Nd₀.₆₇(AsS₄)₂]⁴⁻ chains is observed. But the Nd position is only partially occupied and overall every third Nd atom is missing along the chain. This cuts the infinite chains into short dimers containing two bridging [As₄]³⁻ units and four terminal [AsS₄]³⁻ groups. 1 is characterized with UV/vis diffuse reflectance spectroscopy, IR, and Raman spectra.     

Synthesis and Structural Characterization of a Layered Tin(II) Phosphate, [Sn2(PO4)2][C2N2H10]·H2O

A new layered tin(II) phosphate [Sn₂(PO₄)₂]²⁻[C₂N₂H₁₀]²⁺·H₂O was synthesized by hydrothermal technique. It crystallizes in monoclinic space groupP2₁/c(No. 14) with lattice parametersa=9.4112(1) Å;b=8.5998(1) Å;c=15.9921(2) Å;β=100.009(1)°;V=1274.61(2);Z=4;R=2.06%;R_w=2.17%. The structure consists of inorganic layers, comprising a network of strictly alternating SnO₃and PO₄moieties and held together by strong hydrogen bonding between the layers. Protonated ethylenediamine and water molecules are trapped between the layers.     

Structure determination from powder diffraction data and thermal behaviour of layered lead nitrate oxalate hydrate, Pb2(NO3)2(C2O4).2H2O

The mixed lead nitrate oxalate, Pb₂(NO₃)₂(C₂O₄).2H₂O, has been obtained in a polycrystalline form in the course of a study on precursors of nanocrystalline PZT-type oxides. Its crystal structure has been solved from powder diffraction data collected using a monochromatic radiation from a conventional X-ray source. The symmetry is monoclinic, space group P2₁/c (No. 14), the cell dimensions are a=10.623(2) Å, b=7.9559(9) Å, c=6.1932(5) Å, β=104.49(1)° and Z=4. The structure consists of a stacking of complex double sheets parallel to (1 0 0), forming layers held together by hydrogen bonds. The sheets result from the condensation of PbO₁₀ polyhedra, in which the oxalate and nitrate groups, as well as water molecules, play a major role. The structure is discussed in terms of Pb---O distances, polyhedra shape and lead coordination, with emphasis on the dimensional polymerisation role of water molecules. The thermal behaviour of this layered compound is carefully described from temperature-dependent powder diffraction and thermogravimetric measurements. The enthalpy, Δ_rH=232(3) kJ mol⁻¹, and entropy, Δ_rS=532(8) J K⁻¹ mol⁻¹, of the dehydration reaction have been determined. The high value of Δ_rH demonstrates that the water molecules are strongly bonded in the structure. The complex decomposition proceeds through the crystallisation and decomposition of Pb(NO₃)₂(C₂O₄) into Pb(NO₃)₂ and PbC₂O₄, and, finally, various lead oxides.     

Structure cristalline d'un phosphochromate acide de cuivre potassium: CuK2H2(PCrO7)2

CuK₂H₂(PCrO₇)₂ is monoclinic, P2₁/c, with a unit cell: a=9.559(5)Å; b=7.196(5)Å; c=8.983(5)Å;β=93.73(5)°; Z=2; and D=2.87g/cm³.The crystal structure of this compound has been resolved by using 1938 independent reflections with a final R value of 0.03. The main feature of this compound is the existence of the mixed pyro-group CrPO₇, up to now the first to be described.     

[{(NiOH)2Mo10O36(PO4)Ti2}n]: a novel chainlike trimetal heteropolyanion based on pseudo-keggin fragments

A new mixed Mo/Ni/Ti heteropoly compound [C₅H₅NH]₅ [(NiOH)₂Mo₁₀O₃₆(PO₄)Ti₂] has been hydrothermally synthesized and structurally determined by the single-crystal X-ray diffraction. Black prismatic crystals crystallize in the monoclinic system, space group P2(1)/n, a=11.2075(2), b=37.8328(5) c=13.0888(1) Å, β=101.4580(10)°, M=2276.13, V=5439.19(13) ų, Z=4. Data were collected on a Siemens SMART CCD diffractometer at 293(2) K in the range of 1.68<θ<25.09° using the ω-scan technique (λ=0.71073 Å R(F)=0.0872 for 9621 reflections). The title compound contains a trimetal heteropolyanion polymer and “trans-titanium”-bridging pseudo-Keggin fragments linked to a chain.     

(C6H16N2)Zn3(HPO3)4H2O: a new layered zinc phosphite templated by diprotonated trans-1,4-diaminocyclohexane

Employing trans-1,4-diaminocyclohexane (trans-1,4-DACH) as a template, a new two-dimensional layered zinc phosphite (C₆H₁₆N₂)Zn₃(HPO₃)₄H₂O (1) has been prepared hydrothermally. Single-crystal X-ray diffraction analysis shows that it crystallizes in the monoclinic space group P2₁/n with a=10.458(2) Å, b=14.720(3) Å, c=13.079(3) Å, β=97.93(3)°, V=1994.1(7) ų, Z=4, R₁=0.0349 (I>2σ(I)) and wR₂=0.0605 (all data). The inorganic layer is built up by alternation of ZnO₄ tetrahedra and HPO₃ pseudo pyramids forming a 4.6.8-net. The sheet is featured by a series of capped six-membered rings. The diprotonated trans-1,4-DACH molecules reside in the interlayer region and interact with the inorganic network through H-bonds.     

Vanadium(II) alkyls. Synthesis and X-ray crystal structures of trans-VMe2(dmpe)2 and cis-V(CH2SiMe3) 2(dmpe)2

Treatment of the vanadium(II) tetrahydroborate complex trans-V(η¹-BH₄)₂(dmpe)₂ with (trimethylsilyl) methyllithium gives the new vanadium(II) alkyl cis-V(CH₂SiMe₃)₂(dmpe)₂, where dmpe is the chelating diphosphine 1,2-bis(dimethylphosphino)ethane. Interestingly, this complex could not be prepared from the chloride starting material VCl₂(dmpe)₂. The CH₂SiMe₃ complex has a magnetic moment of 3.8 μ_B, and has been characterized by ¹H NMR and EPR spectroscopy. The cis geometry of the CH₂SiMe₃ complex is somewhat unexpected, but in fact the structure can be rationalized on steric grounds. The X-ray crystal structure of cis-V(CH₂SiMe₃)₂(dmpe)₂ is described along with that of the related vanadium(II) alkyl complex trans-VMe₂(dmpe)₂. Comparisons of the bond distances and angles for VMe₂(dmpe) ₂, V---C = 2.310(5) Å, V---P = 2.455(5) Å, and P---V---P = 83.5(2)° with those of V(CH₂SiMe₃)₂(dmpe)₂, V---C = 2.253(3) Å, V---P = 2.551(1) Å, and P ---V---P = 79.37(3)° show differences due to the differing trans influences of alkyl and phosphine ligands, and due to steric crowding in latter molecule. The V---P bond distances also suggest that metal-phosphorus π-back bonding is important in these early transition metal systems. Crystal data for VMe₂(dmpe)₂ at 25°C: space group P2₁/n, with a = 9.041(1) Å, b = 12.815(2) Å, c = 9.905(2) Å, β = 93.20(1)°, V = 1145.8(5) ų, Z = 2, R_F = 0.106, and R_wF =0.127 for 74 variables and 728 data for which I 2.58 σ(I); crystal data for V(CH₂SiMe₃)₂(dmpe)₂ at −75°C: space group C2/c, with a = 9.652(4) Å, b = 17.958(5) Å, c = 18.524(4) Å, β = 102.07(3)°, V= 3140(3) ų, Z = 4, R_F = 0.033, and R_wF = 0.032 for 231 variables and 1946 data for which I 2.58 σ(I).     

[As(V)As(III)O6]: An uncommon anion group in the crystal structure of K2Cu3(As2O6)2

The crystal structure of K₂Cu₃(As₂O₆)₂ was determined from single-crystal X-ray data by a direct method strategy and Fourier summations [a = 10.359(4) Å, B = 5.388(2)Å, C = 11.234(4) Å, β = 110.48(2)°; space group C2/m; Z = 2; R_w = 0.025 for 1199 reflections up to sin /λ = 0.81 Å⁻¹]. In detail, the structure consists of As(V)O₄ tetrahedra and As(III)O₃ pyramids linked by a common O corner atom to [As(V)As(III)O₆]⁴⁻ groups with symmetry m. The bridging bonds As(V)---O [1.749(3) Å] and As(III)---O [1.838(2) Å] are definitely longer than the other As(V)---O bonds [mean 1.669 Å] and As(III)---O bonds [1.764(2) Å, 2×]. The angle As(V)---O---As(III) is 123.0(1)°. The Cu atoms are [4 + 2]- and [4 + 1]-, and the K atom is [9]-coordinated to oxygen atoms. The As₂O₆ groups and the Cu coordination polyhedra are linked to sheets parallel to (001). These sheets are connected by the K atoms. Single crystals of K₂Cu₃(As₂O₆)₂ suitable for X-ray work were synthesized under hydrothermal conditions.     

Ba2(VO2)(PO4)(HPO4)·H2O, a New Barium Vanadium(V) Phosphate Hydrate Containing Trigonal Bipyramidal VO5Groups

The hydrothermal synthesis, single crystal structure, and some physical properties of Ba₂(VO₂)(PO₄)(HPO₄)·H₂O, a new barium vanadium(V) phosphate hydrate, are reported. This phase is built up from one-dimensional chains of unusual VO₅trigonal bipyramids and (H)PO₄tetrahedra, fused together via V–O–P linkages. These anionic chains propagate along the polar [010] direction. 11-Coordinate barium cations and water molecules occupy the interchain regions and link the chains together. Structural data for this phase and other known barium vanadium phosphates are briefly compared. Crystal data: Ba₂(VO₂)(PO₄)(HPO₄)·H₂O,M_r=566.57, monoclinic, space groupP2₁(No. 4),a=5.0772(5) Å,b=8.724(2) Å,c=10.806(1) Å,β=90.795(8)°,V=478.6(1) ų,Z=2,R=2.65%,R_w=2.89% [147 parameters, 1893 observed reflections withI>3σ(I)].     

(Nb2W4O19), TMA2, Na4(OH2)14(SO4): a new layered structure with Lindqvist heteropolyanions, XAS characterization of the HPAs

The new (Nb₂W₄O₁₉),TMA₂, Na₄(OH₂)₁₄(SO₄) has been evidenced as a minor phase during the Nb₂W₄O₁₉TMA (tetramethylammonium) salt synthesis. Its crystal structure has been refined from single crystal X-ray diffraction data, system monoclinic, a=10.166(5) Å, b=17.93(1) Å, c=24.81(1) Å, β=93.057(7)°, space group (S.G.) C2/c, Z=4, R₁=3.96%, wR₁=4.50%. It shows the stacking of cationic and anionic bidimensional layers. The anionic layer of formula [(Nb₂W₄O₁₉), TMA₂ ]²⁻ is formed of isolated Lindqvist HPAs surrounded by TMA groups. The isolated layers adopt a trigonal symmetry that is lost in the crystal by the association of the cationic sheets. These later, of formula [Na₄(OH₂)₁₄(SO₄)]²⁺ form porous net-like sheets with nearly circular cavities of diameter 7.5 Å. groups host the available cavities in a disordered manner. The cohesion between the sheets is performed by both electrostatic interactions and a set of hydrogen bonds. In the cationic layers, the highly symmetrical surrounding of HPAs by TMA groups yields a homogeneous electrostatic field at their external surface leading to a statistic Nb/W disorder over the three available independent metallic positions. Then, XAS experiments at the L₁/L₃-W edge complementarily helped to highlight the preferential cis configuration of (Nb₂W₄O₁₉)⁴⁻ anions, help to the strong Nb vs W contrast in their contribution to the backscattering paths. Previously to these experiments, it was of course checked that both the two phases present in the prepared sample contain Nb₂W₄O₁₉ anions with nearly unchanged geometry.     

Hydrothermal Synthesis and Crystal Structure of [(CH3NH3)1.03K2.97]Sb12S20·1.34H2O

A novel thioantimonate(III) [(CH₃NH₃)_1.03K_2.97]Sb₁₂S₂₀·1.34H₂O was synthesized hydrothermally. It crystallizes in space groupP , witha=11.9939(7) Å,b=12.8790(8) Å,c=14.9695(9) Å,α=100.033(1)°,β=99.691(1)°,γ=108.582(1)°,V=2095.3(2) ų, andZ=2. The structure is determined from single crystal X-ray diffraction data collected at room temperature and refined toR(F)=0.037. In the crystal structure, each Sb(III) atoms has short bonds (2.37–2.58 Å) to three S atoms. The pyramidal [SbS₃] groups share common S atoms forming two types of centrosymmetric [Sb₁₂S₂₀] rings with the same topology. These rings are interconnected by weaker Sb–S bonds (2.92–3.29 Å) into 2-dimensional layers. Adjacent layers are parallel with K⁺and CH₃NH⁺₃ions and H₂O molecules located between them. Variation of bond valence sums calculated for the Sb(III) cations is found to be correlated with the coordination geometry. This is interpreted as due to the stereochemical activity of their lone electron pairs.     

Joint x-ray and neutron diffraction structure analysis of [(μ-H)3Re3(CO)8{(EtO)2POP(OEt)2}2]

The compound [(μ-H)₃Re₃(CO)₈{(EtO)₂POP(OEt)₂}₂] crystallises in the monoclinic space group P2₁/c with a 18.053(6), b 16.211(5), c 14.800(3) Å, β = 102.41(2)°, and Z = 4. Simultaneous refinement of a single parameter set to fit 3212 X-Ray (sin θ/λ) > 0.352 Å⁻¹ and 1480 neutron data has led to final weighted residuals R_w(F) of 0.096 (X-Ray) and 0.095 (neutron). The molecule exhibits noncrystallographic C₂ symmetry, with two edges of the Re₃ triangle bridged by (OEt)₂POP(OEt)₂ ligands. The hydride ligands lie close to the trimetal plane with each hydride bridging an Re---Re vector. Average molecular parameters involving the hydride ligands are Re---H 1.812(17), Re---Re 3.282(17) Å, Re---H---Re 130(3) and H---Re---H 107.6(27)/dg. All eight carbonyl ligands are terminal, the ligand polyhedron being derived from that in H₃Re₃(CO)₁₂ by substitution of four axial carbonyls by two bidentate phosphite ligands.     

Adjustment of dimensionality in covalent frameworks formed by Co and rhenium cluster chalcocyanide [Re6S8(CN)6]

The synthesis and X-ray structure of a new cluster compound (Pr₄N)₂Co[Re₆S₈(CN)₆] · 6H₂O is reported. It crystallizes in orthorhombic symmetry, P2₁2₁2₁ space group with four formula units per unit cell. The following parameters were found: a = 17.942(9) Å, b = 17.979(4) Å, c = 16.344(8) Å, V=5272 0rA³, ρ_calc=2.607 g cm⁻¹; final R=0.0331. The compound was prepared by interaction of layered Cs₂Co[Re₆S₈(CN)₆] · 2H₂O with aqueous solution of Pr₄NBr. This interaction results in cleavage of covalently linked {Co(H₂O)₂Re₆S₈(CN)₆}_2α²⁻ sheets and in formation of isolated fragments {Co(H₂O)₅Re₆S₈(CN)₆}^u2−. Heating of (Pr₄N)₂Co[Re₆S₈(CN)₆] · 6H₂O results in elimination of two water molecules and in formation of (Pr₄N)₂Co[Re₆S₈(CN)₆] · 4H₂O containing infinite -Co(H₂O)₄-NC-Re₆S₈(CN) ₄-CN-Co(H₂O)₄-chains.     

The Glaserite-like Structure of Double Sodium and Iron Phosphate Na3Fe(PO4)2

The double sodium and iron phosphate Na₃Fe(PO₄)₂ was synthesized and studied by the XRD method, the second harmonic generation technique, and Mössbauer and IR spectroscopy. The compound crystallizes into a monoclinic system (space group C2/c) with unit cell parameters a=9.0736(2) Å, b=5.0344(1) Å, c=13.8732(3) Å, β=91.435(2)° and is found to be related to the K₃Na(SO₄)₂ structure type. The crystal structure was determined by Rietveld analysis (R_wp=5.86, R_I=2.03). Iron cations occupy the M (Na) position while sodium cations occupy the X (K) and Y (K) positions of the glaserite-like structure. Mössbauer spectroscopy shows the presence of high-spin Fe³⁺ in octahedral coordination.     

The Crystal Structures of the Strontium Gallates Sr10Ga6O19 and Sr3Ga2O6

The crystal structures of Sr₁₀Ga₆O₁₉ and Sr₃Ga₂O₆ have been characterized using X-ray diffraction techniques. In the case of Sr₁₀Ga₆O₁₉, the structure was determined from a single crystal diffraction data set collected at room conditions and refined to a final R index of 0.061 for 3471 observed reflections (I>2 σ(I)). The compound is monoclinic with space group C12/c1 (a=34.973(4) Å, b=7.934(1) Å, c=15.943(2) Å, β=103.55(1)°, V=4300.7(6) ų, Z=8, D_calc=4.94 g/cm³, μ(MoKα)=32.04 mm⁻¹) and can be classified as an oligogallate. It is the first example of an inorganic compound where six [TO₄]-tetrahedra of only one chemical species occupying the tetrahedral centres are linked via bridging oxygen atoms to form [T₆O₁₉] groups. The hexamers are not linear, but highly puckered. Eleven symmetrically different Sr cations located in planes parallel (100) crosslink between the oligo-groups. They are coordinated by six to eight oxygen ligands. The structure of Sr₃Ga₂O₆ has been refined from powder diffraction data using the Rietveld method (space group Pa , a=16.1049(1), V=4177.1(1) ų, Z=24, D_calc=4.75 g/cm³). The compound is isostructural with tricalcium aluminate and contains highly puckered, six-membered [Ga₆O₁₈]¹⁸⁻ rings. The rings are linked by strontium cations having six to nine nearest oxygen neighbors.     

X-Ray Diffraction Study of Cs5(HSO4)3(H2PO4)2, a New Solid Acid with a Unique Hydrogen-Bond Network

Solid solution investigations in the CsHSO₄–CsH₂PO₄system, carried out as part of an ongoing effort to elucidate the relationship between proton conduction, hydrogen bonding, and phase transitions, yielded the new compound Cs₅(HSO₄)₃(H₂PO₄)₂. Single-crystal X-ray diffraction methods revealed that Cs₅(HSO₄)₃(H₂PO₄)₂crystallizes in space groupC2/c(or possiblyCc), has lattice parametersa=34.066(19) Å,b=7.661(4) Å,c=9.158(6) Å, andβ=90.44(6)°, a unit cell volume of 2389.9(24) ų, a density of 3.198 Mg m⁻³, and four formula units in the unit cell. Sixteen non-hydrogen atoms and five hydrogen sites were located in the asymmetric unit, the latter on the basis of geometric considerations rather than from Fourier difference maps. Refinement using anisotropic temperature factors for all non-hydrogen atoms and fixed isotropic temperature factors for all hydrogen atoms yielded residuals based onF²(weighted) andFvalues, respectively, of 0.0767 and 0.0340 for observed reflections [F²>2σ(F²)]. The structure contains layers of (CsH₂XO₄)₂that alternate with layers of (CsHXO₄)₃, whereXis P or S. The arrangement of Cs, H, andXO₄groups within the two types of layers is almost identical to that in the end-member compounds, CsH₂PO₄and CsHSO₄-II, respectively. Although P and S each reside on two of the threeXatom sites in Cs₅(HSO₄)₃(H₂PO₄)₂, the number of protons in the structure appears fixed. In addition, the correlation of S–O and S–OH bond distances with O···O distances, where the latter represents the distance between two hydrogen-bonded oxygen atoms, was determined from a review of literature data.