Stereochemistry of Rhodium in Oxygen-Containing Compounds

The Voronoi–Dirichlet polyhedra (VDP) and the method of intersecting spheres were used to perform a crystal-chemical analysis of all compounds studied to date whose structures contain rhodium atoms surrounded by oxygen atoms. All Rh atoms were found to have a coordination number (CN) equal to 6 and to form coordination polyhedra of two types, namely, the distorted octahedra RhO₆ and RhO₅Rh. A coordination number of 6 was found for all Rh(IV), Rh^3.5+, and Rh(III) atoms, while a CN of 5+1 was found typical only of Rh^2.5+ and Rh(II) atoms. The effect of the valence state of Rh on the main features of their crystal-chemical role in the structures is considered in terms of the 18-electron rule.     

Gas Hydrate Frameworks of Allen's Polyhedra. 1. Frameworks on 3–5 Nets

The structures of water molecule frameworks built up of 5¹², 5¹²6², 5¹²6³, and 5¹²6⁴ polyhedra are discussed. In the frameworks of such polyhedra, it is possible to distinguish layers; the centers of the polyhedra belonging to a layer are at the nodes of a planar network consisting of triangular, pentagonal, and hexagonal meshes. The structure of one layer entirely determines the structure of the whole framework. An analysis is given of the structure and topology of frameworks whose layers are constructed on pentagontrigonal nets. It is shown that these frameworks can be constructed from two types of polyhedral blocks closely packed in space.     

Ba3Y2B6O15, a novel cubic borate

Single crystals of tribarium diyttrium hexaborate, which crystallized in the cubic system, have been obtained by spontaneous crystallization from a high‐temperature melt using Li₂O–BaO–B₂O₃ as flux. Its structure is composed of isolated [B₂O₅]⁴⁻ groups, irregular BaO₉ polyhedra and regular YO₆ polyhedra which occupy alternate sites running along the [111] direction. Irregular BaO₉ polyhedra and regular YO₆ polyhedra construct a three‐dimensional framework, which is reinforced by [B₂O₅]⁴⁻ groups.     

Synthesis and crystal structure of [UO2CrO4(C5NH5COO)] · 0.25H2O

[UO₂CrO₄(C₅NH₅COO)] · 0.25H₂O crystals have been synthesized and studied by X-ray diffraction and IR spectroscopy. The compound crystallizes in monoclinic system with the unit cell parameters a = 7.2362(3) ?, b = 13.8847(6) ?, c = 10.7204(5) ?, ?? = 90.037(2)°, space group P2₁/n, Z = 4, R = 0.0236. The structure consists of [UO₂CrO₄(C₅NH₅COO)] chains, which run in the direction [100] and correspond to the AT³B⁰¹ crystallochemical formula, where A = UO ₂ ²⁺ , T³ = CrO ₄ ^2? , and B⁰¹ is nicotinic acid molecules in the form of zwitter ions. The results of analyzing nonbonded interactions in the crystal structure by the method of molecular Voronoi-Dirichlet polyhedra (MMVDP) are presented.     

Nylon 6 9 can crystallize with hydrogen bonding in two and in three interchain directions

Nylon 6 9 has been shown to have structures with interchain hydrogen bonds in both two and in three directions. Chain-folded lamellar crystals were studied using transmission electron microscopy and sedimented crystal mats and uniaxially oriented fibers studied by X-ray diffraction. The principal room-temperature structure shows the two characteristic (interchain) diffraction signals at spacings of 0.43 and 0.38 nm, typical of α-phase nylons; however, nylon 6 9 is unable to form the α-phase hydrogen-bonded sheets without serious distortion of the all-trans polymeric backbone. Our structure has c and c^* noncoincident and two directions of hydrogen bonding. Optimum hydrogen bonding can only occur if consecutive pairs of amide units alternate between two crystallographic planes. The salient features of our model offer a possible universal solution for the crystalline state of all odd–even nylons. The nylon 6 9 room-temperature structure has a C-centered monoclinic unit cell (β = 108°) with the hydrogen bonds along the C-face diagonals; this structure bears a similarity to that recently proposed for nylons 6 5 and X3. On heating nylon 6 9 lamellar crystals and fibers, the two characteristic diffraction signals converge and meet at 0.42 nm at the Brill temperature, T_B · T_B for nylon 6 9 lamellar crystals is slightly below the melting point (T_m), whereas T_B for nylon 6 9 fibers is ≅ 100°C below T_m. Above T_B, nylon 6 9 has a hexagonal unit cell; the alkane segments exist in a mobile phase and equivalent hydrogen bonds populate the three principal (hexagonal) directions. A structure with perturbed hexagonal symmetry, which bears a resemblance to the reported γ-phase for nylons, can be obtained by quenching from the crystalline growth phase (above T_B) to room temperature. We propose that this structure is a “quenched-in” perturbed form of the nylon 6 9 high-temperature hexagonal phase and has interchain hydrogen bonds in all three principal crystallographic directions. In this respect it differs importantly from the γ-phase models. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1153–1165, 1998     

Gas Hydrate Frameworks of Allen's Polyhedra. 2. Frameworks on 3–6 and 3–5–6 Nets

The structure of two classes of water molecule frameworks built up of 5¹²(D), 5¹²6²(T), 5¹²6³(P), and 5¹²6⁴(H) polyhedra is discussed. Polyhedral layers can be distinguished in the frameworks. The centers of the polyhedra belonging to a layer are at the nodes of planar networks consisting of triangular, pentagonal, and hexagonal meshes. The structure of one network determines exclusively the topology of the entire framework. Frameworks on 3–6 nets can be constructed of two types of polyhedral blocks: D₃T₂P₂and D₂T₆. Frameworks on 3–5–6 nets might include both specific blocks and the blocks involved in the frameworks on 3–5 and 3–6 nets. The paper analyzes the structure of frameworks on the nets built as a series of rows, each of these rows being constructed of pentagons or hexagons exclusively. These frameworks are described by the formula (D₃T₂P₂) _x (D₄H₂) _y (D₂T₆) _z , where x 1, y 0, and z 0 (x, y, and z are integers). Since all known frameworks of Allen's polyhedra satisfy this formula, they can be constructed of fragments of gas hydrate lattices with the CS1, CS2, and HS1 structures because they are derivatives of these key structures. Similar frameworks can be constructed of other tetrahedral particles (C, Si, SiO₂, etc.).     

Supraicosahedral polyhedra in carboranes and metallacarboranes: The role of local vertex environments in determining polyhedral topology and the anomaly of 13-vertex closo polyhedra

Metal-free carboranes having 13 vertices are anomalous since their closo polyhedra having the expected 28 skeletal electrons are not the usual deltahedra with exclusively triangular faces but instead polyhedra with one or two trapezoidal faces obtained by removal of one or more edges from the corresponding 13-vertex deltahedron. Removal of such edges converts degree 6 boron vertices in the 13-vertex deltahedron into more favorable degree 5 boron vertices while lowering the degree of nearby carbon vertices. Thus the anomaly of the 13-vertex carborane closo polyhedron can be rationalized by the preference of boron for degree 5 vertices. The 12-vertex tetracarbon carborane (CH₃)₄C₄B₈H₈ with a nido electron count of 28 skeletal electrons but with two quadrilateral faces has a solid state structure derived from a 13-vertex “closo” polyhedron with one quadrilateral face by removal of a degree 4 vertex to give the second quadrilateral face. However, the corresponding tetraethyl derivative (C₂H₅)₄C₄B₈H₈ has a different solid state structure derived from removal of a degree 6 vertex from an unusual 13-vertex deltahedron with three degree 6 vertices to give an open hexagonal face rather than two quadrilateral faces. In contrast to the 13-vertex closo polyhedra, the 14-vertex closo polyhedron is a true deltahedron, namely the D_6d bicapped hexagonal antiprism, which is found in a carborane derivative as well as in several dimetallacarboranes with the metal atoms always at the degree 6 vertices. However, the 15-vertex closo polyhedron, so far found only in the metallaborane 1,2-μ-(CH₂)₃C₂B₁₂H₁₂Ru(η⁶-p-cymene), is a non-deltahedron with one quadrilateral face.     

Structural features of bismuth borates in the system <Emphasis Type="Italic">n</Emphasis>Bi<Subscript>2</Subscript>O<Subscript>3</Subscript>-<Emphasis Type="Italic">m</Emphasis>B<Subscript>2</Subscript>O<Subscript>3</Subscript>

The crystal structures of general composition nBi₂O₃-mB₂O₃ were analyzed and systematized with the use of the structures of borate groups. Based on the CNs calculated by the bond valence method, the shapes of bismuth coordination polyhedra derived from an octahedron were suggested. A correlation was found between the number of BO₃ triangles and BO₄ tetrahedra in borate groups, the average CN of Bi atoms, and the degree of distortion of Bi polyhedra as a function of the m: n ratio, as well as between the polarity of BO₄ tetrahedra and noncentrosymmetry of the structures. The role of Bi³⁺ with the active E pair in the manifestation of specific features of the forms of bismuth polyhedra and the types of connection of boron polyhedra was elucidated.     

The study of Bi3B5O12: synthesis, crystal structure and thermal expansion of oxoborate Bi3B5O12

The paper presents a new data on the crystal structure, thermal expansion and IR spectra of Bi₃B₅O₁₂. The Bi₃B₅O₁₂ single crystals were grown from the melt of the same stoichiometry by Czochralski technique. The crystal structure of Bi₃B₅O₁₂ was refined in anisotropic approximation using single-crystal X-ray diffraction data. It is orthorhombic, Pnma, a=6.530(4), b=7.726(5), c=18.578(5) Å, V=937.2(5) Å³, Z=4, R=3.45%. Bi³⁺ atoms have irregular coordination polyhedra, Bi(1)O₆ (d(B-O)=2.09-2.75 Å) and Bi(2)O₇ (d(B-O)=2.108-2.804 Å). Taking into account the shortest bonds only, these polyhedra are considered here as trigonal Bi(1)O₃ (2.09-2.20 Å) and tetragonal Bi(2)O₄ (2.108-2.331 Å) irregular pyramids with Bi atoms in the tops of both pyramids. The BiO₄ polyhedra form zigzag chains along b-axis. These chains alternate with isolated anions [B₂^IVB₃^IIIO₁₁]⁷⁻ through the common oxygen atoms to form thick layers extended in ab plane. A perfect cleavage of the compound corresponds to these layers and an imperfect one is parallel to the Bi-O chains. The Bi₃B₅O₁₂ thermal expansion is sharply anisotropic (α₁₁≈α₂₂=12, α₃₃=3×10⁻⁶ °C⁻¹) likely due to a straightening of the flexible zigzag chains along b-axis and decreasing of their zigzag along c-axis. Thus the properties like cleavage and thermal expansion correlate to these chains.     

Dilatation thermique anormale et caractere en couches des metavanadates MV2O6 (M = Ca,Cd, Zn,Mg, Pb)

The variations of cell parameters and thermal expansion tensors of metavanadates MV₂O₆ have been measured in the range 77–295 K. The thermal expansion anisotropy is characteristic of layer structures especially for brannerite-type structures (M = Cd, Zn, Mg); this anisotropy is explained by the presence of [VO₅] polyhedra, such as occur in the V₂O₅ layer structure. For CaV₂O₆ the variation of thermal expansion as a function of temperature is abnormal: peaks, typical of a diffuse transition, are observed at 260 K for α₁(T) and α₃(T) curves. The temperature anomaly is reduced when cadmium is substituted for calcium.     

Chemical bonding in EuTGe (T=Ni, Pd, Pt) and physical properties of EuPdGe

EuPdGe was prepared from the elements by reaction in a sealed tantalum tube in a high-frequency furnace. Magnetic susceptibility measurements show Curie-Weiss behavior above 60 K with an experimental magnetic moment of 8.0(1)μ_B/Eu indicating divalent europium. At low external fields antiferromagnetic ordering is observed at T_N=8.5(5) K. Magnetization measurements indicate a metamagnetic transition at a critical field of 1.5(2) T and a saturation magnetization of 6.4(1)μ_B/Eu at 5 K and 5.5 T. EuPdGe is a metallic conductor with a room-temperature value of 5000±500 μΩ cm for the specific resistivity. ¹⁵¹Eu Mössbauer spectroscopic experiments show a single europium site with an isomer shift of δ=−9.7(1) mm/s at 78 K. At 4.2 K full magnetic hyperfine field splitting with a hyperfine field of B=20.7(5) T is observed. Density functional calculations show the similarity of the electronic structures of EuPdGe and EuPtGe. T-Ge interactions (T=Pd, Pt) exist in both compounds. An ionic formula splitting Eu²⁺T⁰Ge²⁻ seems more appropriate than Eu²⁺T²⁺Ge⁴⁻ accounting for the bonding in both compounds. Geometry optimizations of EuTGe (T=Ni, Pt, Pd) show weak energy differences between the two structural types.     

Synthesis, crystal structure and optical properties of a novel sodium lead pentaborate, NaPbB5O9

A novel sodium lead pentaborate, NaPbB₅O₉, has been successfully synthesized by standard solid-state reaction. The single-crystal X-ray structural analysis showed that NaPbB₅O₉ crystallizes in the monoclinic space group P2₁/c with a=6.5324(10) Å, b=13.0234(2) Å, c=8.5838(10) Å, β=104.971(10)°, and Z=4. The crystal structure is composed of double ring [B₅O₉]³⁻ units, [PbO₇] and [NaO₇] polyhedra. [B₅O₉]³⁻ groups connect with each other forming two-dimensional infinite _∞[B₅O₉]³⁻ layers, while [PbO₇] and [NaO₇] polyhedra are located between the layers. [PbO₇] polyhedra linked together via corner-sharing O atom forming novel infinite _∞[PbO₆] chains along the c axis. The thermal behavior, IR spectrum and the optical diffuse reflectance spectrum of NaPbB₅O₉ were reported.     

Cluster self-organization of silicate and germanate systems: Suprapolyhedral precursor nanoclusters and self-assembly of tetrahedral structures of the family A2T2O5 (A = Li, Na; T = Si, Ge): Li2T2O5, Li4Ge3SiO10, Li2Si2O5, and A2Si2O5

Modeling of atomic species (An clusters in the form of atoms or Kn polyhedra, where n is the number of atoms or polyhedra) corresponding to the initial stage of evolution of a chemical system has been carried out. Three series of K4 clusters built of different T tetrahedra (L and T) have been recognized. For L₂T₂ clusters, six geometrically and symmetrically different types of suprapolyhedral clusters have been discovered. The model has been used to identify precursor clusters in A₂T₂O₅ (A = Li, Na; T = Si, Ge) framework structures: A-type Li₂T₂O₅ with space group Cc, B-type Li₄Ge₃SiO₁₀ with space group Abm2, C-type Li₂Si₂O₅ with space group Ccc2, and D-type A₂Si₂O₅ with space group Pbcn. Three (of the six possible) types of suprapolyhedral precursor nanoclusters K4 in the four structures have been identified. The full 3D reconstruction of the self-assembly scenario of crystal structures is as follows: precursor nanocluster ?? primary chain ?? microlayer ?? microframework ?? ?? framework. The bifurcation of structural evolution pathways (structural branching points) at the suprapolyhedral level for type A and B structures is found to occur only when a microframework is formed of equivalent microlayers.     

Numerical evaluation of second and third virial coefficients of some inert gases via classical cluster expansion

In this project we evaluate second virial coefficient of some inert gases via classical cluster expansion, assuming each atomic pair interaction is of Lennard-Jones type. We also try to numerically evaluate the third virial coefficient of Argon gas based on bipolar-coordinate integration (Mas et?al. in J Chem Phys 10:6694, 1999), assuming the same Lennard-Jones potential as before. The second virial coefficient (Vega et?al. in Phys Chem Chem Phys 4:3000–3007, 2002) calculated from our model are compatible to the experimental data [19] The temperature at which B ₂(T) → 0 is called the Boyle’s temperature T _B (Vega et?al. in Phys Chem Chem Phys 4:3000–3007, 2002) for the Lennard-Jines (12-6) potential. For the second virial coefficient of He, we obtain the Boyle’s temperature as follow: T _B ?=?34.9312438964844 (K) B ₂(T) = 9.82958 × 10^?6 (cm³/mol).     

Crystal Structure of a New Form of Sodium Octoborate β-Na2B8O13

Single crystals of a new form of sodium octoborate, β-Na₂B₈O₁₃, were obtained fortuitously from a complex Na₂O-B₂O₃-P₂O₅ mixture, and studied. The compound is monoclinic, space group P2₁/c; the unit cell parameters are a=11.731(4) Å, b=7.880(3) Å, c=10.410(4) Å, β=99.883(3)°; Z=4. The crystal structure was solved from 1653 reflections until R₁=0.0444; it consists of two infinite, independent, and interleaved boron-oxygen networks containing a complex borate anion (B₈O₁₃)²⁻ formed by six BO₃ triangles (Δ) and two BO₄ tetrahedra (T), which can be viewed as a B₅O₁₀ group linked to a B₃O₇ group; this leads to a Fundamental Building Block (FBB) with the shorthand notation: 8: ∞³ [(5:4Δ+T)+(3:2Δ+T)]. This FBB is identical to that described in other octoborates such as α-Na₂B₈O₁₃ and Ag₂B₈O₁₃. However, some subtle differences exist in the interlinking of the octoborate anions found in these three compounds, which explains their different structure and unit cell parameters.     

Structure of bismuth oxoborate Bi<Subscript>4</Subscript>B<Subscript>2</Subscript>O<Subscript>9</Subscript> at 20, 200, and 450°C

Single crystals of bismuth oxoborate Bi₄B₂O₉ have been grown by slowly cooling the melt of a stoichiometric Bi₂O₃ + H₃BO₃ mixture. The structure of the borate (monoclinic space group P2₁/c, a = 11.107 Å, b = 6.629 Å, c = 11.044 Å, β = 91.04°, Z = 4) has been studied at 20, 200, and 450°C. The structure is described not only in terms of full BiO₆ ^? and BiO₇ polyhedra but also in terms of truncated BiO₃ ^? and BiO₄ ^? polyhedra and BO₃ triangles, as well as oxo-centered OBi₃ triangles and OBi₄ tetrahedra. It is shown that both the B-O and Bi-O bond lengths are practically unaffected by temperature. Only the angles between polyhedra change with temperature, being responsible for the strong anisotropy of Bi₄B₂O₆ thermal expansion, which was measured by high-temperature powder X-ray diffraction: α₁₁ = 20, α₂₂ = 15, α₃₃ = 6 × 10^?6 °C^?1, and μ = (c, α₃₃) = ?19°.     

Infrared,Raman and XPS spectroscopic studies of Bi2O3–B2O3–Ga2O3 glasses

Glasses with compositions 60Bi₂O₃–(40?x)B₂O₃–xGa₂O₃ (x = 5, 10, 15, 20 mol%) are prepared by conventional melting method. The thermal properties are investigated by differential thermal analysis (DTA) and the structures of the glasses were probed by Infrared, Raman and X-ray photoelectron spectroscopy (XPS). The results show that density, refractive index and optical basicity increase with the increase of Ga₂O₃. The glass transition temperature (T_g), the onset crystallization temperature (T_x), ΔT (T_x?T_g) decrease with the content of Ga₂O₃. The cut-off edges in ultraviolet and infrared shift to longer wavelength with the increase of Ga₂O₃. On the other hand, the addition of Ga₂O₃ causes a progressive coordination number change of the boron atom from 3 to 4. XPS result indicates both Bi⁵⁺ and Bi³⁺ exist in 5 mol% Ga₂O₃ content, while Bi⁵⁺ amounts decrease with the increase of Ga₂O₃ contents. The glass is mainly composed of [BiO₆], [BO₃], [BO₄] and [GaO₄] polyhedra. Glasses are supposed to have layer structure. [BO₃] triangle and [BO₄] tetrahedra may be located between the [GaO₄] tetrahedral and [BiO₆] octahedra to prevent crystallization and to compensate electric charge.     

Preparation, crystal structure and magnetic behavior of new double perovskites Sr2B′UO6 with B′=Mn, Fe, Ni, Zn

Sr₂B′UO₆ double perovskites with B′=Mn, Fe, Ni, Zn have been prepared in polycrystalline form by solid-state reaction, in air or reducing conditions. These new materials have been studied by X-ray diffraction (XRD), magnetic susceptibility and magnetization measurements. The room-temperature crystal structure is monoclinic (space group P2₁/n), and contains alternating B′O₆ and UO₆ octahedra sharing corners, tilted along the three pseudocubic axes according to the Glazer notation a⁻a⁻b⁺. The magnetic measurements show a spontaneous magnetic ordering below T_N=21 K for B′=Mn, Ni, and T_C=150 K for B′=Fe. From a Curie-Weiss fit, the effective paramagnetic moment for B′=Mn (5.74 μ_B/f.u.) and B′=Ni(3.51 μ_B/f.u.) are significantly different from the corresponding spin-only moments for the divalent cations, suggesting the possibility of a partial charge disproportionation B′²⁺+U⁶⁺⇔B′³⁺+U⁵⁺, also accounting for plausible ferrimagnetic interactions between B′ and U sublattices. The strong curvature of the reciprocal susceptibility for B′=Fe precludes a Curie-Weiss fit but also suggests the presence of ferrimagnetic interactions in this compound. This charge disproportionation effect is also supported by the observed B′O distances, which are closer to the expected values for high-spin, trivalent Mn, Fe and Ni cations.     

Structure of the La12GdEuB6Ge2O34 borogermanate as probed by NMR and IR spectroscopy

The structure of fine crystalline borogermanate La₁₂GdEuB₆Ge₂O₃₄ has been studied by NMR and IR spectroscopy. It has been demonstrated that this compound is isostructural to the homonuclear Ln₁₄B₆Ge₂O₃₄ compounds (Ln = Pr-Gd) and crystallizes in space group P3₁. The rare-earth elements have been distributed over the LnO _n polyhedra in La₁₂GdEuB₆Ge₂O₃₄ by analogy with the known structures. Lanthanum can occupy positions with CN 7–10, and the symmetry of these LnO _n coordination polyhedra is not higher than C _2v . In the La₁₂GdEuB₆Ge₂O₃₄ structure, the LnO _n coordination polyhedra are formed by oxygen atoms of oxo groups and anions, some of the oxygen atoms being shared by LnO _n polyhedra. The BO₃ and GeO₄ groups in the structure are also bridging, i.e., are involved in bonding of LnO _n polyhedra. One of the B-O bonds in La₁₂EuGd(BO₃)₆(GeO₄)₂O₈ is elongated as compared with the B-O bond lengths in homonuclear compounds Pr₁₄(BO₃)₆(GeO₄)₂O₈ and Nd₁₄(BO₃)₆(GeO₄)₂O₈. In the La₁₂GdEuB₆Ge₂O₃₄ structure, germanium is located in isolated GeO₄ tetrahedra with distorted T _d symmetry. The local symmetry of lanthanum in fine crystalline La₁₂GdEuB₆Ge₂O₃₄ have been assessed using ¹³⁹La NMR (B ₀ = 7.04 T, room temperature). For comparison, binary lanthanum compounds with a simpler structure— LaBO₃, La(BO₂)₃, and La₂GeO₅—have been used. The spectra of all compounds are rather broad (ν_1/2 = 180–240 kHz). The ¹³⁹La NMR spectra of the LaBO₃, La(BO₂)₃, and La₁₂GdEu(BO₃)₆(GeO₄)₂O₈ borates show a signal at (1080 ± 40) ppm, which is absent in the spectrum of La₂GeO₅. The shape of the ¹³⁹La NMR spectra of La₁₂GdEu(BO₃)₆(GeO₄)₂O₈ and LaBO₃ is characterized by the second-order quadrupole splitting with a downfield shoulder. The similarity of these spectra points to close ¹³⁹La NMR chemical shifts of La₁₂GdEu(BO₃)₆(GeO₄)₂O₈ and LaBO₃. No quadrupole splitting was observed in the spectra of La(BO₂)₃ and La₂GeO₅.     

Synthesis and crystal structure of Bi6.4Pb0.6P2O15.2: A new polymorph in the series Bi6+xM1−xP2O15+y

Bi_6.4Pb_0.6P₂O_15.2 is a polymorph of structures with the general stoichiometry Bi_6+xM_1−xP₂O_15+y. However, unlike previously published structures that consist of layers formed by edge sharing OBi₄ tetrahedra bridged by PO₄ and TO₆ (T=transition metal) tetrahedra and octahedra the title compound's structure is more complex. It is monoclinic, C2, a=19.4698(4) Å, b=11.3692(3) Å, c=16.3809(5) Å, β=101.167(1)°, Z=10. Single-crystal X-ray diffraction data were refined by least squares on F² converging to R₁=0.0387, wR₂=0.0836 for 7023 intensities. The crystal twins by mirror reflection across (001) as the twin plane and twin component 1 equals 0.74(1). Oxygen ions are in tetrahedral coordination to four metal ions and the O(BiPb)₄ units share corners to form layers that are part of the three-dimensional framework. Eight oxygen ions form a cube around the two crystallographically independent Pb ions. Pb-O bond lengths vary from 2.265(14) to 2.869(14) Å. Pairs of such cubes share an edge to form a Pb₃O₂₀ unit. The two oxygen ions from the unshared edges are part of irregular Bi polyhedra. Other oxygen ions of Bi polyhedra are part only of O(BiPb)₄ units, and some oxygen ions of the polyhedra are also part of PO₄ tetrahedra. One, two, three and or four PO₄ moieties are connected to the Bi polyhedra. Bi-O bond lengths ?3.1 Å vary from 2.090(12) to 3.07(3) Å. The articulations of Pb cubes, Bi polyhedra and PO₄ tetrahedra link into the three-dimensional structure.