Präparation,Kristallstruktur und thermisches Verhalten der Quecksilber(I)phosphate α-(Hg2)3(PO4)2, β-(Hg2)3(PO4)2 und (Hg2)2P2O7

Contributions on Crystal Structures and Thermal Behaviour of Anhydrous Phosphates. XXIII. Preparation, Crystal Structure, and Thermal Behaviour of the Mercury(I) Phosphates α-(Hg₂)₃(PO₄)₂, β-(Hg₂)₃(PO₄)₂, and (Hg₂)₂P₂O₇ Light-yellow single crystals of (Hg₂)₂P₂O₇ have been obtained via chemical vapour transport in a temperature gradient (500 °C → 450 °C, 23 d) using Hg₂Cl₂ as transport agent. Characteristic feature of the crystal structure (P2/n, Z = 2, a = 9,186(1), b = 4,902(1), c = 9,484(1) Å, β = 98,82(2)°, 1228 independent of 5004 reflections, R(F) = 0,066 for 61 variables, 7 atoms in the asymmetric unit) are Hg₂²⁺-units with d(Hg1–Hg1) = 2,508 Å and d(Hg2–Hg2) = 2,519 Å. The dumbbells Hg₂²⁺ are coordinated by oxygen, thus forming polyhedra [(Hg1₂)O₄] and [(Hg2₂)O₆]. These polyhedra share some oxygen atoms. In addition they are linked by the diphosphate anion P₂O₇^4– (ecliptic conformation; ∠(P,O,P) = 129°) to built up the 3-dimensional structure. Under hydrothermal conditions (T = 400 °C) orange single crystals of the mercury(I) orthophosphates α-(Hg₂)₃(PO₄)₂ and β-(Hg₂)₃(PO₄)₂ have been obtained from (Hg₂)₂P₂O₇ and H₃PO₄ (c = 1%). The crystal structures of both modifications have been refined from X-ray single crystal data [α-form (β-form): P2₁/c (P2₁/n), Z = 2 (2), a = 8,576(3) (7,869(3)), b = 4,956(1) (8,059(3)), c = 15,436(3) (9,217(4)) Å, β = 128,16(3) (108,76(4))°, 1218 (1602) independent reflections of 4339 (6358) reflections, R(F) = 0,039 (0,048) for 74 (74) variables, 8 (8) atoms in the asymmetric unit]. In the structure of α-(Hg₂)₃(PO₄)₂ three crystallographically independent mercury atoms, located in two independent dumbbells, are coordinated by three oxygen atoms each. Thus, [(Hg₂)O₆] dimers with a strongly distorted tetrahedral coordination of all mercury atoms are formed. Such dimers are present besides [(Hg₂)O₅]-polyhedra in the less dense crystal structure of β-(Hg₂)₃(PO₄)₂ (d(Hg–Hg) = 2,518 Å). The mercury(I) phosphates are thermally labile and disproportionate between 200 °C (β-(Hg₂)₃(PO₄)₂) and 480 °C (α-(Hg₂)₃(PO₄)₂) to elemental mercury and the corresponding mercury(II) phosphate.     

Synthese und Kristallstruktur von K2(HSO4)(H2PO4), K4(HSO4)3(H2PO4) und Na(HSO4)(H3PO4)

Synthesis and Crystal Structure of K₂(HSO₄)(H₂PO₄), K₄(HSO₄)₃(H₂PO₄), and Na(HSO₄)(H₃PO₄) Mixed hydrogen sulfate phosphates K₂(HSO₄)(H₂PO₄), K₄(HSO₄)₃(H₂PO₄) and Na(HSO₄)(H₃PO₄) were synthesized and characterized by X‐ray single crystal analysis. In case of K₂(HSO₄)(H₂PO₄) neutron powder diffraction was used additionally. For this compound an unknown supercell was found. According to X‐ray crystal structure analysis, the compounds have the following crystal data: K₂(HSO₄)(H₂PO₄) (T = 298 K), monoclinic, space group P 2₁/c, a = 11.150(4) Å, b = 7.371(2) Å, c = 9.436(3) Å, β = 92.29(3)°, V = 774.9(4) ų, Z = 4, R₁ = 0.039; K₄(HSO₄)₃(H₂PO₄) (T = 298 K), triclinic, space group P 1, a = 7.217(8) Å, b = 7.521(9) Å, c = 7.574(8) Å, α = 71.52(1)°, β = 88.28(1)°, γ = 86.20(1)°, V = 389.1(8)ų, Z = 1, R₁ = 0.031; Na(HSO₄)(H₃PO₄) (T = 298 K), monoclinic, space group P 2₁, a = 5.449(1) Å, b = 6.832(1) Å, c = 8.718(2) Å, β = 95.88(3)°, V = 322.8(1) ų, Z = 2, R₁ = 0,032. The metal atoms are coordinated by 8 or 9 oxygen atoms. The structure of K₂(HSO₄)(H₂PO₄) is characterized by hydrogen bonded chains of mixed H_nS/PO₄^– tetrahedra. In the structure of K₄(HSO₄)₃(H₂PO₄), there are dimers of H_nS/PO₄^– tetrahedra, which are further connected to chains. Additional HSO₄^– tetrahedra are linked to these chains. In the structure of Na(HSO₄)(H₃PO₄) the HSO₄^– tetrahedra and H₃PO₄ molecules form layers by hydrogen bonds.     

Sur L'Existence d'un Intermediaire Reactionnel Entre Phosphate et Pyrophosphate Acide de Potassium: Cas de K2H8(PO4)2P2O7

On the Existence of Intermediate Reaction Products of Potassium Hydrogen Phosphate and Diphosphate: K₂H₈(PO₄)₂P₂O₇ The crystal structure of K₂H₈(PO₄)₂P₂O₇ has been determined from diffractometer data obtained using MoKα radiation. The space group is Pca2₁ with a = 9.364(2), b = 7.458(2) and c = 19.560(2) Å, V = 1 366.0 ų; d_m = 2.17(1) g/cm³. Z = 4 · μ(MoKα) = 12.47 cm^?1. The structure was solved by direct methods. The crystal structure was refined to R = 0.025 for 416 independent reflexions. Two kinds of PO₄ exist and the mean value of P? O is 1.55(2) Å for one and 1.53(2) Å for the other. In P₂O₇ the angle P? O? P is 135(1)°. The distances P? O of bridge are 1.59(2) and 1.57(2) Å the mean value of P? O in terminals ? PO₃ is 1.51(2) Å. The coordination numbers of the potassium ions are nine and eight. K₂H₈(PO₄)₂P₂O₇, compound with mixed anion PO₄/P₂O₇ may be considered as reactional intermediary between acid orthophosphate and pyrophosphate.     

Beiträge zum thermischen Verhalten und zur Kristallchemie von wasserfreien Phosphaten XXXII [1] Neue Orthophosphate des zweiwertigen Chroms — Mg3Cr3(PO4)4, Mg3, 75Cr2, 25(PO4)4, Ca3Cr3(PO4)4 und Ca2, 00Cr4, 00(PO4)4

Contributions on Crystal Chemistry and Thermal Behaviour of Anhydrous Phosphates. XXXII. New Orthophosphates of Divalent Chromium — Mg₃Cr₃(PO₄)₄, Mg_{3, 75}Cr_{2, 25}(PO₄)₄, Ca₃Cr₃(PO₄)₄ and Ca_{2, 00}Cr_{4, 00}(PO₄)₄ Solid state reactions via the gas phase led in the systems A₃(PO₄)₂ / Cr₃(PO₄)₂ (A = Mg, Ca) to the four new compounds Mg₃Cr₃(PO₄)₄ ( A ), Mg_3.75Cr_2.25(PO₄)₄ ( B ), Ca₃Cr₃(PO₄)₄ ( C ), and Ca_2.00Cr_4.00(PO₄)₄ ( D ). These were characterized by single crystal structure investigations [( A ): P2₁/n, Z = 1, a = 4.863(2) Å, b = 9.507(4) Å, c = 6.439(2) Å, β = 91.13(6)°, 1855 independend reflections, 63 parameters, R1 = 0.035, wR2 = 0.083; ( B ): P2₁/a, Z = 2, a = 6.427(2) Å, b = 9.363(2) Å, c = 10.051(3) Å, β = 106.16(3)°, 1687 indep. refl., 121 param., R1 = 0.032, wR2 = 0.085; ( C ): P‐1, Z = 2, a = 8.961(1) Å, b = 8.994(1) Å, c = 9.881(1) Å, α = 104.96(2)°, β = 106.03(2)°, γ = 110.19(2)°, 2908 indep. refl., 235 param., R1 = 0.036, wR2 = 0.111; ( D ): C2/c, Z = 4, a = 17.511(2) Å, b = 4.9933(6) Å, c = 16.825(2) Å, β = 117.95(1)°, 1506 indep. refl., 121 param., R1 = 0.034, wR2 = 0.098]. The crystal structures contain divalent chromium on various crystallographic sites, each showing a (4+n)‐coordination (n = 1, 2, 3). For the magnesium compounds and Ca_2.00Cr_4.00(PO₄)₄ a disorder of the divalent cations Mg²⁺/Cr²⁺ or Ca²⁺/Cr²⁺ is observed. Mg_3.75Cr_2.25(PO₄)₄ adopts a new structure type, while Mg₃Cr₃(PO₄)₄ is isotypic to Mg₃(PO₄)₂. Ca₃Cr₃(PO₄)₄ and Ca_2.00Cr_4.00(PO₄) ₄ are structurally very closely related and belong to the Ca₃Cu₃(PO₄)₄‐structure family. The orthophosphate Ca₉Cr(PO₄)₇, containing trivalent chromium, has been obtained besides C and D .     

The Oxidation of Heterogeneous Tl/Ni/P‐Alloys — Preparation and Crystal Structures of the Thallium Nickel Phosphates TlNi4(PO4)3, Tl4Ni7(PO4)6, and Tl2Ni4(P2O7)(PO4)2

Single crystals of the first anhydrous thallium nickel phosphates were prepared by reaction of heterogeneous Tl/Ni/P alloys with oxygen. TlNi₄(PO₄)₃ (pale‐yellow, orthorhombic, space group Cmc2₁, a = 6.441(2)Å, b = 16.410(4)Å, c = 9.624(2)Å, Z = 4) crystallizes with a structure closely related to that of NaNi₄(PO₄)₃. Tl₄Ni₇(PO₄)₆ (yellow‐brown, monoclinic, space group Cm, a = 10.711(1)Å, b = 14.275(2)Å, c = 6.688(2)Å, β = 103.50(2)°, Z = 8) is isotypic with Na₄Ni₇(PO₄)₆, and Tl₂Ni₄(P₂O₇)(PO₄)₂ (brown, monoclinic, space group C2/c, a = 10.389(2)Å, b = 13.888(16)Å, c = 18.198(3)Å, β = 103.1(2)°, Z = 8) adopts the K₂Ni₄(P₂O₇)(PO₄)₂ structure. Tl₂Ni₄(P₂O₇)(PO₄)₂ could also be prepared in nearly single phase form by reaction of Tl₂CO₃, NiO, and (NH₄)₂HPO₄.     

Synthesis,Structural Characterization,and Cation Transport of Tripotassium Pentabismuth Arsenate K3Bi5(AsO4)6

During the exploration of the K₂O-Bi₂O ₃ -As₂O₅ system, single crystals of a new arsenate of trivalent bismuth, K₃Bi₅(AsO₄) ₆, were isolated by solid state reaction at 600°C. The title compound crystallizes in the monoclinic system, space group C2/c (N°15) with a = 18.257(2) Å, b = 7.260(1) Å, c = 20.130(4) Å, β = 119.86(1)°, and Z = 4. Its structure consists of a three-dimensional framework made up of AsO₄ tetrahedra and BiO₆ and BiO₇ polyhedra sharing edges and corners, delimiting cavities wherein K⁺ ions reside. This compound exhibits a potassium ion conductivity but with rather low conductivity value.     

Crystal structure and cation transport properties of the layered monodiphosphates Rb6Bi4(PO4)2(P2O7)3

Single crystals of the new Bi(III) phosphates, Rb₆Bi₄(PO₄)₂(P₂O₇)₃, have been isolated and their structure has been determined by X-ray diffraction techniques. This compound crystallizes in the monoclinic space group P2₁/c with a=9.077(1)Å, b=9.268(2)Å, c=36.418(6)Å, β=95.75(1)° and Z=8. The crystal structure is made up of BiO₅ and BiO₆ polyhedra sharing the corners with PO₄ tetrahedra and P₂O₇ diphosphate groups. The structure can be described as infinite anionic layers with composition [Bi₄(PO₄)₂(P₂O₇)₃]_∞⁶⁻ parallel to the [301] plane, connected via P-O-Bi bridges to form a three-dimensional open framework. This framework delimits tunnels running along [100] and [010] directions, where the rubidium ions reside. This compound exhibits a rubidium ion conduction but with rather low conductivity value at 640 K.     

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°.     

Preparation,Single Crystal Structure Analysis,and Thermal Behaviour of the Acidic Mercury(I) Phosphate (Hg2)2(H2PO4)(PO4)

Yellowish single crystals of acidic mercury(I) phosphate (Hg₂)₂(H₂PO₄)(PO₄) were obtained at 200 °C under hydrothermal conditions in 32% HF from a starting complex of microcrystalline (Hg₂)₂P₂O₇. Refinement of single crystal data converged at a conventional residual R[F² > 2σ(F²)] = 3.8% (C2/c, Z = 8, a = 9.597(2) Å, b = 12.673(2) Å, c = 7.976(1) Å, β = 110.91(1)°, V = 906.2(2) ų, 1426 independent reflections > 2σ out of 4147 reflections, 66 variables). The crystal structure consists of Hg₂²⁺‐dumbbells and discrete phosphate groups H₂PO₄^– and PO₄^3–. The Hg₂²⁺ pairs are built of two crystallographically independent Hg atoms with a distance d(Hg1–Hg2) = 2.5240(6) Å. The oxygen coordination sphere around the mercury atoms is asymmetric with three O atoms for Hg1 and four O atoms for Hg2. The oxygen atoms belong to the different PO₄ tetrahedra, which in case of H₂PO₄‐groups are connected by hydrogen bonding. Upon heating over 230 °C, (Hg₂)₂(H₂PO₄)(PO₄) condenses to (Hg₂)₂P₂O₇, which in turn disproportionates at higher temperatures into Hg₂P₂O₇ and elemental mercury.     

Synthese und Kristallstruktur von Te3O3(PO4)2, einer Verbindung mit fünffach koordiniertem Tellur(IV)

Synthesis and Crystal Structure of Te₃O₃(PO₄)₂, a Compound with 5‐fold Coordinate Tellurium(IV) Polycrystalline Te₃O₃(PO₄)₂ is formed during controlled dehydration of (Te₂O₃)(HPO₄) with (Te₈O₁₀)(PO₄)₄ as an intermediate product. Colourless single crystals were prepared by heating stoichiometric amounts of the binary oxides P₂O₅ und TeO₂ in closed silica glass ampoules at 590 °C for 8 hours. The crystal structure (P2₁/c, Z = 4, α = 12.375(2), b = 7.317(1), c = 9.834(1)Å, β = 98.04(1)°, 1939 structure factors, 146 parameters, R[F² > 2σ(F²)] = 0.0187, wR2(F² all) = 0.0367) was determined from four‐circle diffractometer data and consists of [TeO₅] polyhedra und PO₄ tetrahedra as the main building units. The framework structure is made up of cationic zigzag‐chains of composition [Te₂O₃]²⁺ which extend parallel to [001] and anionic [Te(PO₄)₂]^2— units linked laterally to these chains. This leads to the formation of [Te₂O₃][Te(PO₄)₂] layers parallel to the bc plane which are interconnected via weak Te‐O bonds.     

Darstellung,Kristallstrukturen und Eigenschaften der Chrom(II)-phosphat-halogenide Cr2(PO4)Br und Cr2(PO4)I

Synthesis, Crystal Structures, and Properties of the Chromium(II) Phosphate Halides Cr₂(PO₄)Br and Cr₂(PO₄)I The new compounds Cr₂(PO₄)Br and Cr₂(PO₄)I have been obtained by reaction of CrPO₄, Cr and Br₂ or I₂ in evacuated silica tubes at elevated temperatures (Cr₂(PO₄)Br: 900 °C, Cr₂(PO₄)I: 700 °C). Single crystals of deep blue Cr₂(PO₄)Br and turquoise Cr₂(PO₄)I with edge-lengths up to 2 mm and 0.3 mm, respectively, have been grown in experiments involving the gaseous phase. Single crystal data have been used for structure determination and refinement. Though being not isotypic, the two crystal structures are closely related. Two crystallographically independent Cr²⁺, in polyhedra [Cr1O₃X₃] and [Cr2O₅X], form dimers [Cr1₂O₂O_2/2X₄] and [Cr2₂O₈X₂]. Distances are 1.978 Å ≤ d(Cr–O) ≤ 2.096 Å (for the iodide: 1.959 Å ≤ d(Cr–O) ≤ 2.105 Å), 2.587 Å ≤ d(Cr–Br) ≤ 3.158 Å and 2.867 Å ≤ d(Cr–I) ≤ 3.327 Å. The structures of bromide and iodide can be distinguished by the different way of connection of the Cr1 containing dimers. The phosphate group shows slightly distorted tetrahedral geometry with 1.491 Å ≤ d(P–O) ≤ 1.559 Å (1.486 Å ≤ d(P–O) ≤ 1.567 Å) and angles of 106.48° ≤ ∠(O–P–O) ≤ 111.69° (106.57° ≤ ∠(O–P–O) ≤ 111.72°. IR-spectra of Cr₂(PO₄)Br and Cr₂(PO₄)I, the Raman-spectrum of Cr₂(PO₄)Br and electronic spectra of the two compounds in the UV/vis region at low temperature are reported and discussed.     

Etude des spectres vibrationnels et des proprietes physico-chimiques du cyclotriphosphate mixte de nickel et de sodium hexahydrate,NiNa4(P3O9)2.6H2O

A study of the vibrational spectra and physico-chemical properties of nickel and sodium cyclotriphosphate hexahydrate, NiNa₄(P₃O₉)₂.6H₂O. We have studied the dehydration and the calcination under atmospheric pressure of cyclotriphosphate hexahydrate of nickel and sodium, NiNa₄(P₃O₉)₂.6H₂O, between 25 and 700°C by infrared spectrometry, X-ray diffraction, TGA and DTA thermal analyses. This study allows the identification and the crystallographic characterization of a new phase, NiNa₄(PO₃)₆, obtained between 350 and 450°C. NiNa₄(PO₃)₆ crystallizes in the triclinic system, P₋₁, with the following unit cell parameters a = 6.157(3)Å, b = 6.820(6)Å, c = 10.918(6)Å, α = 80.21(5)°, β= 97.80(9)°, γ = 113.49(3)°, V = 409.8 ų, Z = 1, M(19) = 25 and F(19) = 48 (0.0095; 42). The calcination of NiNa₄(PO₃)₆, between 500 and 600°C, leads to a mixture of long-chain polyphosphates NiNa(PO₃)₃ and NaPO₃. The kinetic characteristics of the dehydration of NiNa₄(P₃O₉)₂.6H₂O were determined and discussed. The vibrational spectrum of the title compound, NiNa₄(P₃O₉)₂.6H₂O, was interpreted in the domain of the stretching vibrations of the P₃O₉ rings, on the basis of its crystalline structure and in the light of the calculation of the normal IR frequencies of the P₃O₉ ring with D_3h symmetry.     

Beiträge zum thermischen Verhalten wasserfreier Phosphate. IX. Darstellung und Kristallstruktur von Cr6(P2O7)4. Ein gemischtvalentes Pyrophosphat mit zwei- und dreiwertigem Chrom

Contributions on the Thermal Behaviour of Anhydrous Phosphates. IX. Synthesis and Crystal Structure of Cr₆(P₂O₇)₄. A Pyrophosphate Containing Di- and Trivalent Chromium Cr₆(P₂O₇)₄ (Cr₂²⁺Cr₄³⁺(P₂O₇)₄) can be obtained reducing CrPO₄ by phosphorus (950°C, 48 h, 100 mg iodine as mineralizer). By means of chemical transport reactions (transport agent iodine; 1050 → 950°C) the compound has been separated from its neighbour phases (Cr₂P₂O₇, CrP₃O₉) and crystallized (greenish, transparent crystals; edge length up to 0.3 mm). The crystal structure of Cr₆(P₂O₇)₄ (Spcgrp.: P-1; z = 1; a = 4.7128(8) Å, b = 12.667(3) Å, c = 7.843(2) Å, α = 89.65(2)°, β = 92.02(2)°, γ = 90.37(2) has been solved and refined from single crystal data (2713 unique reflections, 194 parameter, R = 0.035). Cr²⁺ is surrounded by six oxygen atoms which occupy the corners of an elongated octahedron (4 × d^{Cr? O} ≈? 2.04 Å; 2 × d^{Cr? O} ≈? 2.62 Å). The Cr³⁺ ions are also coordinated octahedraly (1.930 Å ≤ d_{Cr? O} ≤ 2.061 Å). The crystallographically independent pyrophosphate groups show nearly eclipsed conformation. The bridging angles (P? O? P) are 136.5° and 138.9° respectively.     

Crystal structures of polyphosphates MCs<Subscript>5</Subscript>(PO<Subscript>3</Subscript>)<Subscript>8</Subscript> (M = Pr,Eu, and Gd)

Crystals of double polyphosphates EuCs₅(PO₃)₈ (I) and GdCs₅(PO₃)₈ (II) have been studied by X-ray diffraction. The isostructural crystals of I and II are monoclinic, space group C2. Only unit cell parameters have been determined for the crystals of double Pr and Cs polyphosphate (III). This crystal is isostructural with earlier studied La₃Cs₁₅P₂₄O₇₂ · 6H₂O (IV). The crystals of compounds III and IV are triclinic, space group P1, Z = 1; a = 11.987(2) and 12.178(5) Å, b = 14.754(8) and 14.740(8) Å, c = 14.692(8) and 14.847(9) Å, α = 60.15(4)° and 60.87(5)°, β = 67.04(4)° and 66.35(4)°, γ = 78.76(3)° and 77.54(4)°, respectively. In compounds I and II, the polyphosphate anions exist as infinite chains. The M^IIIO₈ polyhedra are isolated from each other but share edges and faces with the CsO _n polyhedra.     

Von kleinen Bausteinen zu neuen Poly‐alkoxo‐oxometallat‐Derivaten: Synthese und Strukturaufklärung von K4[VIV12O12(OCH3)16(C4O4)6], Cs10[VIV24O24(OCH3)32(C4O4)12][VIV8O8(OCH3)16(C2O4)] und M2[VIV8O8(OCH3)16(VIVOF4)] (M = [N(nBu)4] bzw. [NEt4])

>From Small Fragments to New Poly‐alkoxo‐oxo‐metalate Derivatives: Syntheses and Crystal Structures of K₄[V^IV₁₂O₁₂(OCH₃)₁₆(C₄O₄)₆], Cs₁₀[V^IV₂₄O₂₄(OCH₃)₃₂(C₄O₄)₁₂][V^IV₈O₈(OCH₃)₁₆(C₂O₄)], and M₂[V^IV₈O₈(OCH₃)₁₆(V^IVOF₄)] (M = [N(nBu)₄] or [NEt₄]) By solvothermal reaction of ortho‐vanadicacid ester [VO(OMe)₃] with squaric acid and potassium or caesium hydroxide the compounds K₄[V^IV₁₂O₁₂(OCH₃)₁₆(C₄O₄)₆] ( 2 ) and Cs₁₀[V^IV₂₄O₂₄(OCH₃)₃₂(C₄O₄)₁₂][V^IV₈O₈(OCH₃)₁₆(C₂O₄)] ( 3 ) could be syntesized. With tetra‐n‐butyl‐ or tetra‐n‐ethylammonium fluoride [N(nBu)₄]₂[V^IV₈O₈(OCH₃)₁₆(V^IVOF₄)] ( 4 ) and [N(Et)₄]₂[V^IV₈O₈(OCH₃)₁₆(V^IVOF₄)] ( 5 ) could be isolated. In 2 and 3 the corners of a tetrahedron or cube resp. are occupied by {(VO)₃(OMe)₄} groups and connected along the edges of the tetrahedron resp. cube by six or twelve resp. squarato‐groups. The octanuclear anions in the compounds 3 , 4 , and 5 are assumedly built up by fragments of the ortho‐vanadicacid ester [VO(OMe)₃]. Around the anions C₂O₄^2— or VOF₄^— these oligormeric chains are closed to a ring . Crystal data: 2 , tetragonal, P4₃, a = 18.166(3)Å, c = 29.165(7)Å, V = 9625(3)ų, Z = 4, d_c = 1.469 gcm^—3; 3 , orthorhombic, Pbca, a = 29.493(5)Å, b = 25.564(4)Å, c = 31.076Å, V = 23430(6)ų, Z = 4, d_c = 1.892 gcm^—3; 4 , monoclinic, P2₁/n, a = 9.528(1)Å, b = 23.021(2)Å, c = 19.303(2)Å, β = 92.570(2)°, V = 4229.8(5)ų, Z = 2, d_c = 1.391 gcm^—3; 5 , monoclinic, P2₁/n, a = 16.451(2)Å, b = 8.806(1)Å, c = 23.812(1)Å, β = 102.423(2)°, V = 3368.7(6)ų, Z = 2, d_c = 1.534 gcm^—3.     

Crystal Growth,Single‐Crystal Structure Refinement and Unusual Ligand‐Field Splittings of Lazulite‐Type Oxidephosphates MTi2O2(PO4)2 (M = FeII,CoII, NiII)

Single crystals of oxidephosphates MTi₂O₂(PO₄)₂ [M: Fe (dark red), Co (pinkish red), Ni (green)] with edge‐lengths up to 0.4 mm were grown by chemical vapour transport. FeTi₂O₂(PO₄)₂ and CoTi₂O₂(PO₄)₂ are isotypic to NiTi₂O₂(PO₄)₂. The crystal structure of the latter was previously solved from powder data [FeTi₂O₂(PO₄)₂ (data for CoTi₂O₂(PO₄)₂ and NiTi₂O₂(PO₄)₂ in brackets): monoclinic, P2₁/c, Z = 2, a = 7.394(3) (7.381(6), 7.388(4)) Å, b = 7.396(2) (7.371(5), 7.334(10)) Å, c = 7.401(3) (7.366(6), 7.340(3)) Å, β = 120.20(3) (120.26(6), 120.12(4))°, R₁ = 0.0393 (0.0309, 0.0539) wR₂ = 0.1154 (0.0740, 0.1389), 2160 (1059, 1564) independent reflections, 75 (76, 77) variables]. The single‐crystal study allowed improved refinement using anisotropic displacement parameters, yielded lower standard deviations for the structural parameters and revealed a small amount of cation disordering. Twinning and cation disordering within the structures are rationalized by a detailed crystallographic classification of the MTi₂O₂(PO₄)₂ structure type in terms of group‐subgroup relations. The structure is characterized by a three‐dimensional network of [PO₄] tetrahedra and [M^IITi₂O₁₂] groups formed by face‐sharing of [M^IIO₆] and [TiO₆] octahedra. Electronic absorption spectra of MTi₂O₂(PO₄)₂ in the UV/VIS/NIR region show rather large ligand‐field splittings for the strongly trigonally distorted chromophors [M^IIO₆] (M = Fe, Co, Ni) with interelectronic repulsion parameters beeing slightly smaller than in other phosphates. Interpretation of the spectra within the framework of the angular overlap model reveals a significant second‐sphere ligand field effect of Ti^IV ions on the electronic levels of the Ni^II and Co^II.     

Tetraammonium Diglycinyl‐octamolybdate(VI) Dihydrate, (NH4)4[(NH3CH2CO)2(Mo8O28)] · 2 H2O

The reaction of ammonium heptamolybdate with hydrazine sulfate in an aqueous solution of glycine at room temperature yielded colorless crystals of (NH₄)₄[(NH₃CH₂CO)₂(Mo₈O₂₈)] · 2 H₂O. The crystal is monoclinic, space group C2/c (no. 15), a = 17.234 Å, b = 10.6892 Å, c = 18.598 Å, β = 108.280°, V = 3253.2 ų, Z = 4. The crystal structure contains ammonium cations and isolated octamolybdate(4–) anions, [(NH₃CH₂CO)₂(Mo₈O₂₈)]^4–, with two zwitterionic glycine molecules as ligands.     

Ag3BiO3 und Ag5BiO4, die ersten Silberoxobismutate(III)

Ag₃BiO₃ and Ag₅BiO₄,the first Silver Oxobismuthates(III) Applying high oxygen pressures (100 MPa) Ag₃BiO₃ and Ag₅BiO₄ were prepared for the first time by reacting the binary components Ag₂O and Bi₂O₃ at temperatures between 770 and 800 K. Single crystals of both compounds were grown hydrothermally from Ag₂O and Bi₂O₃ at 620 K and at oxygen pressures of 10 MPa. The crystal structure determination (Ag₃BiO₃: I4₁, a = 14.1924(1), c = 8.7997(1) Å, Z = 16, 1 729 diffractometer data, R_w = 0.057; Ag₅BiO₄: P2₁/n, a = 5.855(1), b = 8.984(1), c = 12.457(1) Å, β = 91.49(1)Å, Z = 4, 2716 diffractometer data, R_w = 0.036) shows that in Ag₅BiO₄ bismuth approximately has a square pyramidal coordination by five oxygen atoms. Two such pyramids share an edge thus forming ‘isolated’ Bi₂O₈^10? anions. In Ag₃BiO₃ the same groups are linked by the terminal oxygen atoms to form a three dimensional network. In both structures the cation arrangements form variants of the Laves-phases MgCu₂ with silver occupying the copper positions. The Mg positions are ordered occupied by bismuth and silver.     

Complex Topology of Uranyl Polyphosphate Frameworks: Crystal Structures of α‐, β‐K[(UO2)(P3O9)] and K[(UO2)2(P3O10)]

Three new uranyl polyphosphates, α‐K[(UO₂)(P₃O₉)] ( 1 ), β‐K[(UO₂)(P₃O₉)] ( 2 ), and K[(UO₂)₂(P₃O₁₀)] ( 3 ), were prepared by high‐temperature solid‐state reactions. The crystal structures of the compounds have been solved by direct methods: 1 – monoclinic, P2₁/m, a = 8.497(1), b = 15.1150(1), c = 14.7890(1) Å, β = 91.911(5)°, V = 1898.3(3) ų, Z = 4, R₁ = 0.0734 for 4181 unique reflections with |F₀| ≥ 4σ_F; 2 – monoclinic, P2₁/n, a = 8.607(1), b = 14.842(2), c = 14.951(1) Å, β = 95.829(5)°, V = 1900.0(4) ų, Z = 4, R₁ = 0.0787 for 3185 unique reflections with |F₀| ≥ 4σ_F; 3 – Pbcn, a = 10.632(1), b = 10.325(1), c = 11.209(1) Å, V = 1230.5(2) ų, Z = 4, R₁ = 0.0364 for 1338 unique reflections with |F₀| ≥ 4σ_F. In the structures of 1 and 2 , phosphate tetrahedra share corners to form infinite [PO₃]^? chains, whereas, in the structure of 3 , tetrahedra form linear [P₃O₁₀]^5? trimers. The structures are based upon 3‐D frameworks of U and P polyhedra linked by sharing common O corners. The infinite [PO₃]^? chains in the structures of 1 and 2 are parallel to [100] and [–101], respectively. The uranyl polyphosphate frameworks are occupied by host K⁺ cations.     

MII(C4H12N2)[B2P3O12(OH)] (MII = Co,Zn): Synthesis and Crystal Structure of Novel Open Framework Borophosphates

Two novel borophosphates, M^II(C₄H₁₂N₂)[B₂P₃O₁₂(OH)] (M^II = Co, Zn), exhibiting open frameworks, have been synthesized by hydrothermal reactions (T = 165 °C). The crystal structures of the isotypic compounds have been determined both at 293 K (orthorhombic, Ima2 (no. 46), Z = 4; M^II = Co: a = 12.4635(4) Å, b = 9.4021(4) Å, c = 11.4513(5) Å, V = 1341.90 ų, R₁ = 0.0202, wR₂ = 0.0452, 2225 observed reflections with I > 2σ(I); M^II = Zn: a = 12.4110(9) Å, b = 9.4550(5) Å, c = 11.4592(4) Å, V = 1344.69 ų, R₁ = 0.0621, wR₂ = 0.0926, 1497 observed reflections with I > 2σ(I)). Distorted CoO₆‐octahedra and ZnO₅‐square‐pyramids, respectively, share common oxygen‐corners with BO₄‐, PO₄‐ and (HO)PO₃‐tetrahedra. The tetrahedral groups are linked via common corners to form infinite loop‐branched borophosphate chains [B₂P₃O₁₂(OH)^4–]. The open framework of M^II‐coordination polyhedra and tetrahedral borophosphate chains contains a three‐dimensional system of interconnected structural channels running along [100], [011] and [011], respectively, which are occupied by di‐protonated piperazinium ions.