Crystal structure of <Emphasis Type="Italic">p</Emphasis>-carboxyphenylhydrazone benzoylacetone

The crystal structure of p-carboxyphenylhydrazone benzoylacetone is determined. The crystals are monoclinic, a = 13.614(4) Å, b = 11.388(2) Å, c = 20.029(6) Å, β = 104.82(2)°, V = 2339(9) ų, Z = 8, space group C2/c, and R = 0.038 for 1622 reflections with I > 2σ(I). The crystal is built of C₁₇H₁₄N₂O₄ neutral molecules that are linked by O-H?O hydrogen bonds between the carboxyl groups into centrosymmetric pseudodimers. The effect of carboxylation of the phenylhydrazone fragment and the position of the carboxyl group on the molecular packing in the crystal is determined. The N(1)-H(1N)?O(1) intramolecular hydrogen bond (N-H, 0.94 Å; H?O, 1.87 Å; N?O, 2.59 Å; and the N-H?O angle, 133°) is formed in the molecule.     

Molecular structures of chalcone podands: A prognosis of photoinduced transformations in the crystals

A series of chalcone podands with the propenone group in the ortho position of the bridging aryl substituent with respect to the oxyethylene fragment is synthesized. The influence of the preorganization of the chalcone podand molecules in crystals on their ability to participate in topochemical reactions is investigated. From analyzing the X-ray structural data, the highest probability of the solid-state photochemical [2 + 2]cycloaddition is predicted for podands with phenyl substituents and the oxyethylene fragment containing two or three oxygen atoms. The X-ray structural data for the chalcone podand C₃₂H₂₆O₄ (3a) are as follows: a = 7.904(9) Å, b = 14.92(2) Å, c = 21.30(3) Å, β = 91.7(1)°, monoclinic system, space group P2₁/c, Z = 4, V = 2510(5) ų, ρ = 1.26 g/cm³, and R = 0.046; C₃₄H₃₀O₅ (3b): a = 15.738(9) Å, b = 11.889(2) Å, c = 15.0830(15) Å, β = 105.47(14)°, monoclinic system, space group C2/c, Z = 4, V = 2720.0(9) ų, ρ = 1.266 g/cm³, and R = 0.0418; C₃₂H₂₄N₂O₈ (4a): a = 17.9416(18) Å, b = 10.9703(8) Å, c = 41.699(2) Å, β = 105.970(11)°, monoclinic system, space group P2₁/c, Z = 4, V = 2781.4(5) ų, ρ = 1.348 g/cm³, and R = 0.0426; C₃₆H₃₂N₂O₁₀ (4c): a = 7.6286(5)Å, b = 17.9398(10) Å, c = 11.5890(3)Å, β = 95.287(4)°, monoclinic system, space group P2₁/n, Z = 2, V = 1579.27(14) ų, ρ = 1.372 g/cm³, and R = 0.0377; and C₂₈H₂₂O₆ (5a): a = 15.6032(10) Å, b = 8.1131(5) Å, c = 17.7334(11) Å, β = 91.381(5)°, monoclinic system, space group C2/c, Z = 4, V = 2244.2(2) ų, ρ = 1.345 g/cm³, and R = 0.0309.     

Synthesis and structures of thienyl-substituted 5-dipyrromethane isomers

The compounds 5(2-thienyl)-and 5(3-thienyl)-dipyrromethane (1 and2, respectively) have been synthesized and isolated from the acid-catalyzed reaction between thiophenes-carboxaldehyde and pyrrole. Characterization by X-ray diffraction confirms molecular structures involving twoortho-substituted pyrrolyl and one thienyl groups. Both the compounds1 and2 were crystallized in the monoclinic space groupP2₁/n with cell parametersa = 5.7149(16) Å,b = 17.338(6) Å, andc = 11.785(4) Å, β = 98.466(9)^°,V = 1155.0(6) ų for compound1; anda = 5.828(4) Å,b = 17.424(10) Å,c = 11.822(8) Å, β = 98.10(2)^°, andV = 1188.4(13) ų for compound2.     

Crystal structure of zinc(II) hydrated trinuclear complex with monoprotonated ethylenediaminetetraacetate anion(3−), [Zn<Subscript>3</Subscript>(H<Emphasis Type="Italic">Edta</Emphasis>)<Subscript>2</Subscript>(H<Subscript>2</Subscript>O)<Subscript>6</Subscript>]

The crystal structure of the [Zn₃(HEdta)₂(H₂O)₆] complex (I) is determined by X-ray diffraction analysis. The crystals are orthorhombic, a = 14.780 Å, b = 29.699 Å, c = 7.032 Å, Z = 4, and space group Pna2₁. The structural units of crystals I are trinuclear linear molecules, in which the peripheral atoms Zn(1) and Zn(2) each coordinate two N atoms and three O atoms of the HEdta ^3? ligand and the O(w) atom of the H₂O molecule, whereas the central Zn(3) atom coordinates four O(w) atoms of the H₂O molecules and two terminal O atoms of the two HEdta ^3? ligands. The HEdta ^3? ligand fulfills a hexadentate chelating—bridging function. The bond lengths are as follows: Zn-O(HEdta), 2.006(4)–2.123(4) Å; Zn-N, 2.214(6) and 2.128(5) Å; and Zn-O(w), 2.006(6)–2.225(5) Å. In structure I, there is a specific contact formed by hydrogen bonds, owing to which the distance between the central atoms of individual molecules appears to be shorter than that in covalently bonded complexes.     

Crystal structure of 2,4,6-trinitropyridine and its N-oxide

The structures of 2,4,6-trinitropyridine (TNPy) and its N-oxide were determined by X-ray single crystal diffraction. TNPy and 2,4,6-trinitropyridine-1-oxide (TNPyO) crystallize in space groupPbcn andPnma, respectively. The crystallographic parameters are as follows: TNPy,a = 28.573(6) Å,b = 9.7394(19) Å, andc = 8.7566(18) Å, α = β = γ = 90^°, μ = 0.164 mm^?1,V = 2436.8(8) ų,z = 12,Dx = 1.751 mg/mm³,F(000) = 1296,T = 293(2) K, 1.43^°≤ θ≤ 27.40^°, the finalR factor:R ₁ = 0.0574,wR ₂ = 0.1337. TNPyO,a = 9.6272(19) Å,b = 14.128(3) Å, andc = 5.9943(12) Å, α = β = γ = 90^°, μ = 0.179 mm^?1,V = 815.3(3)ų,z = 4,Dx = 1.875 mg/mm³,F(000) = 464,T = 293(2) K, 2.88^°≤ θ≤ 27.44^°, the finalR factor:R ₁ = 0.0497,wR ₂ = 0.1515.     

Crystal and molecular structure of 2-[(4-nitrophenyl)carbonyl]cyclohex-1-ene-1-yl 4-nitrobenzoate

The crystal structure of 2-[(4-nitrophenyl)carbonyl]cyclohex-1-ene-1-yl 4-nitrobenzoate is studied (T = 173 K, R1 = 0.0354 for 2713 observed reflections). This crystal is orthorhombic, a = 7.8367(8) Å, b = 9.6082(10) Å, c = 23.856(3) Å, V = 1796.3(3) ų, space group P2₁2₁2₁, and Z = 4. The molecule has a folded configuration, which is stabilized by π-π interactions between its two parts. A system of intermolecular C-H...O hydrogen bonds (H...O, 2.44–2.67 Å; CHO angles 122°–169°) and intramolecular C-H...O contacts closing five-membered cycles (H...O, 2.42–2.59 Å; CHO angles 96°–102°) are formed in the structure.     

X-ray diffraction investigation of <Emphasis Type="Italic">trans</Emphasis>-2,8-dihydroxy-2,4,4′, 6,6′,8,10,10′,12,12′-decamethyl-5,11-dicarbacyclohexasiloxane and <Emphasis Type="Italic">trans</Emphasis>-1,4-dihydroxy-1,4-dimethyl-1,4-disilacyclohexane

The crystal structures of two organosilicon compounds are studied by X-ray diffraction. Crystals of trans-2,8-dihydroxy-2,4,4′,6,6′,8,10,10′,12,12′-decamethyl-5,11-dicarbacyclohexasiloxane, C₁₂H₃₆O₆Si₆, (I) are studied at 293 K [a = b = 16.310(4) Å, c = 9.849(3) Å, V = 2620(1) ų, d_calcd = 1.128 g/cm³, space group P4(2)/n, Z = 4, 3370 reflections, wR2 = 0.1167, R1 = 0.0472 for 2291 reflections with F > 4σ(F)]. Crystals of trans-1,4-dihydroxy-1,4-dimethyl-1,4-disilacyclohexane, C₆H₁₆O₂Si₂, (II) are studied at 110 K [a = 6.8253(5) Å, b = 9.5495(8) Å, c = 12.0064(10) Å, α = 101.774(2)°, β = 102.203(2)°, γ = 95.068(2)°, V = 741.8(1) ų, d_calcd = 1.184 g/cm³, space group \(P\bar 1\), Z = 3, 6267 reflections, wR2 = 0.1052, R1 = 0.0421 for 3299 reflections with F > 4σ(F)]. It is found that the conformation of the ring in compound I, which contains two methylene groups in the cyclohexasiloxane ring, differs from those in its analogues containing only oxygen atoms or one methylene group in the ring. The noticeable difference between the SiCSi angle [123.0(2)°] and the tetrahedral angle is characteristic of cyclohexasiloxanes. Structure II contains three independent molecules with very close conformations. The cyclohexane rings adopt a chair conformation. The methylene groups in II, in distinction to those in I, are characterized by a standard tetrahedral coordination.     

Coordination dimers constructed from metal(II) halides and the organic ligand 1,2-dimethoxy- 4,5-bis(2-pyridylethynyl)benzene

A series of new coordination compounds has been synthesized using the organic ligand 1,2-dimethoxy-4,5-bis(2-pyridylethynyl)benzene (dmpeb). The compounds all form dimers consisting of two metal cations bridged by two ligand molecules. Charge balance is provided by halide ligands, and the four-coordinate metal centers are distorted from the ideal tetrahedral environment. [CoCl₂(dmpeb)]₂ (1) crystallizes in the monoclinic space group P2₁/n with a = 8.5272(6) Å, b = 18.3653(13) Å, c = 13.3493(9) Å, β = 103.574(2)^°, V = 2032.2(2) ų, Z = 2. [ZnCl₂(dmpeb)]₂ (2) is isostructural to 1 and has the cell parameters a = 8.5495(4) Å, b = 18.4049(8) Å, c = 13.3692(6) Å, β = 103.4460(10)^°, V = 2046.01(16) ų, Z = 2. [ZnBr₂(dmpeb)]₂ (3) is also isostructural to 1 with a = 8.7882(5) Å, b = 18.7260(12) Å, c = 13.3857(8) Å, β = 102.5990(10)^°, V = 2149.8(2) ų, Z = 2. Additionally, the compounds [ZnI₂(dmpeb)]₂ (4, cell parameters: a = 8.9650(5) Å, b = 19.1251(10) Å, c = 13.4160(7) Å, β = 101.1660(10)^°, V = 2256.7(2) ų, Z = 2), [HgCl₂(dmpeb)]₂ (5, cell parameters: a = 8.8457(7) Å, b = 18.4030(15) Å, c = 13.3711(11) Å, β = 104.246(2)^°, V = 2109.7(3) ų, Z = 2), and [HgBr₂(dmpeb)]₂ (6, cell parameters: a = 9.0576(5) Å, b = 18.8634(11) Å, c = 13.4535(8) Å, β = 102.9780(10)^°, V = 2239.9(2) ų, Z = 2) are also isostructural to 1. A seventh dimeric compound, [HgI₂(dmpeb)]₂, not isostructural to the others was also characterized by X-ray crystallography. [HgI₂(dmpeb)]₂ (7) crystallizes in the triclinic space group P-1 with a = 8.8028(5) Å, b = 12.0990(7) Å, c = 12.4082(7) Å, α = 109.7240(10)^°, β = 107.3680(10)^°, γ = 93.0880(10)^°, V = 1169.57(12) ų, Z = 1.     

X-ray mapping in heterocyclic design: XIV. Tricyclic heterocycles based on 2-Oxo-1,2,5,6,7,8-hexahydroquinoline-3-carbonitrile

The structures of four compounds are studied using single-crystal X-ray diffraction: 1-[2-(4-chlorophenyl)-2-oxoethyl]-2-oxo-1,2,5,6,7,8-hexahydroquinoline-3-carbonitrile [a = 4.908(4) Å, b = 11.644(10) Å, c = 13.587(2) Å, β = 94.31(5)°, Z = 2, space group P2₁]; 2-[2-(4-chlorophenyl)-2-oxoethoxy]-5,6,7,8-tetrahydroquinoline-3-carbonitrile [a = 7.6142(8) Å, b = 14.778(2) Å, c = 14.132(2) Å, β = 100.38(1)°, Z = 4, space group P2₁/c]; 4-(aminocarbonyl)-2-(chlorophenyl)-6,7,8,9-tetrahydro[1.3]oxazolo[3,2-a]quinolin-3-ium per-chlorate [a = 5.589(7) Å, b = 24.724(15) Å, c = 13.727(5) Å, β = 97.66(9)°, Z = 4, space group P2₁/n]; and (3-amino-5,6,7,8-tetrahydrofuro[2,3-b]quinolin-2-yl)-(4-chlorophenyl) methanone [a = 7.150(2) Å, b = 7.4288(10) Å, c = 15.314(3) Å, α = 98.030(10)°, β = 99.21(2)°, γ = 105.34(2)°, Z = 2, space group \(P\bar 1\)]. The structures are solved by direct methods and refined by the full-matrix least-squares procedure in the anisotropic approximation to R = 0.0728, 0.0439, 0.1228, and 0.0541, respectively. The structure of 1-(4-chlorophenyl)-4-piperidin-1-yl-8,9-dihydro-7H-pyrrolo[3.2.1-ij]quinoline-5-carboxamide [a = 23.9895(9) Å, b = 5.1557(3) Å, c = 17.0959(9) Å, β = 106.43°, Z = 4, space group P ₁/c] is investigated by X-ray powder diffraction. This structure is solved using the grid search procedure and refined by the Rietveld method to R _wp = 0.0773, R _exp = 0.0540, R _p = 0.0585, R _b = 0.1107, and χ ² = 1.78.     

Synthesis and characterization of 9-(4-nitrophenyl)3,3,6,6-tetramethyl-3,4,6,7,9,10-hexahydro-1,8(2H,5H) acridinedione and its methoxyphenyl derivative

9-(4-Nitrophenyl)-3,3,6,6-tetramethyl-3,4,6,7,9,10-hexahydro-1,8(2H,5H) acridinedione (NTHA) crystallizes in orthorhombic space group P2₁2₁2₁ with a = 5.9716(1) Å, b = 18.0476(3) Å, c = 19.2445(2) Å, V = 2074.04(5) ų, Z = 4, D_cal = 1.263 Mg m^?3 and R = 0.0521 (wR = 0.1326) for 4078 observed reflections. 9-(4-Nitrophenyl)-10-(4-methoxyphenyl)-3,3,6,6-tetramethyl-3,4,6,7,9,10-hexahydro-1,8(2H,5H) acridinedione NMTHA, crystallizes in monoclinic space group P2₁/c with a = 15.669(5) Å, b = 10.652(4) Å, c = 18.337(6) Å, β = 108.25(1)^°, V = 2906.66(2) ų, Z = 4, D_cal = 1.245 Mg m^?3 and R = 0.0725 (wR = 0.1847) for 5105 observed reflections. The experimental values are compared with the theoretical values calculated based on the semiemperical methods. The structures are stabilized by N–H?sO and C–H?sO types of intermolecular interactions in addition to van der Waals forces.     

X-ray mapping in heterocyclic design: XII. X-ray diffraction study of 2-pyridones containing cycloalkane fragments annelated to the C(5)-C(6) bond

The structures of 4,6-dimethyl-1H-pyridin-2-one [a = 6.125(2) Å, b = 15.153(4) Å, and c = 14.477(4) Å, Z = 8, space group Pbca], the 2: 1: 1 complex of 4-methyl-1,5,6,7-tetrahydro-2H-cyclopenta[b]pyridin-2-one with phosphoric acid and methanol [a = 11.181(2) Å, b = 14.059(6) Å, c = 13.593(4) Å, β = 97.78(2)°, Z = 8, space group P2₁/n], 4-methyl-1,5,6,7,8,9-hexahydro-2H-cyclohepta[b]pyridin-2-one [a = 12.565(6) Å, b = 5.836(6) Å, c = 13.007(3) Å, β = 93.10(3)°, Z = 4, space group P2₁/n], and 4-methyl-5,6,7,8,9,10-hexahydrocycloocta[b]pyridin-2(1H)-one [a = 12.955(3) Å, b = 6.1595(15) Å, c = 13.038(3) Å, β = 95.50(2)°, Z = 4, space group P2₁/n] are determined by single-crystal X-ray diffraction. The structures are solved by direct methods and refined by the full-matrix least-squares procedure in the anisotropic approximation to R = 0.0755, 0.0644, 0.0754, and 0.0569, respectively. The structures of 4-methyl-1,5,6,7-tetrahydro-2H-cyclopenta[b]pyridin-2-one [a = 7.353(4) Å, b = 8.176(4) Å, c = 13.00(1) Å, β = 105.64(2)°, Z = 4, space group P2₁/c] and 2-oxo-1,2,5,6,7,8-hexahydroquinoline-3-carbonitrile [a = 5.9870(2) Å, b = 16.5280(5) Å, c = 9.6540(3) Å, β = 111.52(4)°, Z = 4, space group P2₁/c] are studied by the powder diffraction technique. The structures are solved using the grid search procedure and refined by the Rietveld method to R _wp = 0.108 and 0.058, R_exp = 0.032 and 0.027, R _p = 0.076 and 0.043, R _b = 0.123 and 0.077, and χ² = 7.9 and 3.64, respectively. In all the structures, hydrogen bonds involving the N, H, and O atoms of the pyridone fragment are formed.     

Calcio-olivine γ-Ca<Subscript>2</Subscript>SiO<Subscript>4</Subscript>: I. Rietveld refinement of the crystal structure

The structure of the natural mineral calcio-olivine (γ-Ca₂SiO₄) found in skarn xenoliths in the region of the Lakargi Mountain (North Caucasus, Kabardino-Balkaria, Russia) is refined by the Rietveld method [a = 5.07389(7) Å, b = 11.21128(14) Å, c = 6.75340(9) Å, V = 384.170(5) ų, Z = 4, ρ_calcd = 2.98 g/cm³, space group Pbnm]. The X-ray diffraction pattern of a powdered sample is recorded on a STOE STADI MP diffractometer [λCuK _α1; Ge(111) primary monochromator; 6.00° < 2θ < 100.88°; step width, 2.5° in 2θ; number of reflections, 224]. All calculations are performed with the WYRIET (version 3.3) software package. The structural model is refined in the anisotropic approximation to R _p = 6.44, R _wp = 8.52, R _exp = 5.85, R _B = 4.98, R _F = 6.90, and s = 1.46. It is shown that the sample under investigation is a mixture of several mineral phases, among which calcio-olivine (the natural analogue of the γ-Ca₂SiO₄ compound) (83%), hillebrandite (13%), and wadalite (4%) are dominant. Only the scale factors and the unit cell parameters are refined for hillebrandite Ca₂SiO₃(OH)₂ [a = 3.63472(16) Å, b = 16.4140(10) Å, c = 11.7914(8) Å, space group Cmc2₁, Z = 6] and wadalite Ca₆Al₅Si₂O₁₆Cl₃ (a = 12.0088 Å, space group, I \(\bar 4\)3d Z = 4). The results of the structure refinement of the main component of the sample confirm that the mineral calcio-olivine is isostructural to the synthetic compound γ-Ca₂SiO₄. The structure of this compound is formed by the heteropolyhedral framework composed of Ca octahedra joined together into olivine-like ribbons and isolated Si tetrahedra.     

Crystal Structures of Diphosphinated Chromium Fischer Amino Carbenes

The crystal structures of four new diphosphinated chromium Fischer amino carbenes with the compositions fac-[(P-P)(CO)₃Cr=C(NR₂′)(R)] (R = Me, NR₂′ = pyrrolidino, P-P = dppe, 1; R = Me, NR₂′ = pyrrolidino, P-P = dppp, 2; R = Me, R′ = Me, P-P = dppe, 3; R = Me, R′ = Me, P-P = dppp, 4) have been determined at 243 K. Compound 1 crystallizes in the monoclinic system, space group P2₁ /n with a = 12.1597(11) Å, b = 20.1556(17) Å, c = 14.0557(12) Å, β = 114.163(3)°, V = 3143.0(5) Å³, and Z = 4. Compound 2 crystallizes in the triclinic system, space group P ? 1 with a = 7.4424(3) Å, b = 10.8830(5) Å, c = 20.6040(9) Å, α = 100.9880(10)°, β = 91.7650(10)°, γ = 97.6610(10)°, V = 1620.90(12) Å³, and Z = 2. Compound 3 crystallizes in the monoclinic system as a mono-solvate of d⁵-pyridine, space group P2₁ /c with a = 11.485(2) Å, b = 22.825(5) Å, c = 14.092(3) Å, β = 108.53(3)°, V = 3502.7(12) Å³, and Z = 4. Compound 4 crystallizes in the orthorhombic system, space group P2 ₁ 2 ₁ 2 ₁ with a = 8.359(3) Å, b = 15.364(6) Å, c = 23.784(9) Å, V = 3055(2) Å³, and Z = 4. Steric repulsions with the diphosphine ligand favor a conformation with the amino moiety directed away from the diphosphine backbone in 1–4.     

New data on vlasovite: Refinement of the crystal structure and the radiation damage of the crystal during the x-ray diffraction experiment

The crystal structure of vlasovite obtained from the Kipawa alkaline complex in Quebec is refined to R _F = 0.053 for 1515 unique reflections with |F| > 4σ(F). The parameters of the monoclinic unit are as follows: a = 11.063(8) Å, b = 10.15(1) Å, c = 8.60(1) Å, β = 100.3(1)°, space group C2/c, and Z = 4. The X-ray diffraction, electron microprobe, and IR spectroscopic data indicate that, under X-ray radiation, the specimen suffers radiation damage, which is accompanied by a partial removal of Na atoms, incorporation of H₂O molecules into the structure, and, possibly, a change in the configuration of the (Si,O) framework.     

Crystal structure of SrFe(<Emphasis Type="Italic">EDTA</Emphasis>)Cl · 5H<Subscript>2</Subscript>O

The crystal structure of the SrFe(Edta)Cl · 5H₂O (I) complex is determined. The crystals are monoclinic, a = 7.530(4) Å, b = 10.575(3) Å, c = 23.308(10) Å, β = 95.75(4)°, Z = 4, and space group P2₁/c. The structural units of I are infinite ribbons of the molecular type that are formed by tetranuclear fragments. A tetranuclear fragment involves the centrosymmetric positively charged dimer group [Sr(H₂O)₄Cl] ₂ ²⁺ at the center and the [Fe(Edta)(H₂O)]_? anionic complexes, which compensate for the positive charge of the dimer group, at the periphery. These constituents are bound via bridging oxygen atoms of the Edta ligands. The coordination number of the Sr atom is nine. The Sr-O bond lengths lie in the range between 2.552 and 2.766 Å, the Sr-Cl bond length is 3.216(3) Å, and the Sr?Sr distance is 4.371(1) Å. The parameters of the [Fe(Edta)(H₂O)]^? group are within the range of values observed in such complexes: Fe-O, 1.996–2.086(3) Å; Fe-O(w), 2.110(4) Å; and Fe-N, 2.289(4) and 2.327(4) Å. Separate ribbons are linked by hydrogen bonds involving all H₂O molecules and terminal oxygen atoms of the Edta ligand.     

X-ray mapping in heterocyclic design: XV. Tricyclic heterocycles based on 2-oxo-2,5,6,7-tetrahydro-1<Emphasis Type="Italic">H</Emphasis>-cyclopenta[<Emphasis Type="Italic">b</Emphasis>]pyridine-3-carbonitrile

The structures of five compounds are studied using single-crystal X-ray diffraction: 2-oxo-2,5,6,7-tetrahydro-1H-cyclopenta[b]pyridine-3-carbonitrile [a = 15.641(8) Å, b = 9.373(5) Å, c = 7.387(4) Å, β = 92.91(5)°, Z = 4, space group P2₁/c]; 1-[2-(4-chlorophenyl)-2-oxoethyl]-2-oxo-2,5,6,7-tetrahydro-1H-cyclopenta[b]pyridine-3-carbonitrile [a = 4.728(4) Å, b = 28.035(11) Å, c = 11.184(3) Å, Z = 4, space group P2₁2₁2₁]; 2-[2-(4-chlorophenyl)-2-oxoethoxy]-6,7-dihydro-5H-cyclopenta[b]pyridine-3-carbonitrile [a = 10.1202(13) Å, b = 11.2484(18) Å, c = 13.4323(19) Å, β = 102.05(1)°, Z = 4, space group P2₁/c]; 2-(4-chlorophenyl)-3a, 6,7,8-tetrahydrocyclopenta[e][1.3]oxazolo[3.2-a]pyridine-4-carboxamide perchlorate [a = 7.702(2) Å, b = 9.599(3) Å, c = 23.798(5) Å, β = 93.44(2)°, Z = 4, space group P2₁/c]; and (3-amino-6,7-dihydro-5H-cyclopenta[b]furo[3.2-e]pyridin-2-yl)(4-chlorophenyl)methanone [a = 7.3273(2) Å, b = 13.390(3) Å, c = 28.792(8) Å, Z = 8, space group Pbca]. The structures are solved using direct methods and refined by the full-matrix least-squares procedure in the anisotropic approximation to R = 0.0580, 0.0724, 0.0469, 0.0477, and 0.0418, respectively.     

Crystal structure of new micalike titanosilicate—bussenite,Na<Subscript>2</Subscript>Ba<Subscript>2</Subscript>Fe<Superscript>2+</Superscript>[TiSi<Subscript>2</Subscript>O<Subscript>7</Subscript>][CO<Subscript>3</Subscript>]O(OH)(H<Subscript>2</Subscript>O)F

The crystal structure of mineral bussenite, Na₂Ba₂Fe[TiSi₂O₇][CO₃]O(OH)(H₂O)F, found in the Khibiny massif (the Kola Peninsula) has been determined. The parameters of the triclinic unit-cell are a = 5.399(3) Å, b = 7.016(9) Å, c = 16.254(14) Å, α = 102.44(8)°, β = 93.18(6)°, γ = 90.10(7)°, sp. gr. \(P\bar 1\), R = 0.054 for 1418 reflections with |F| > 2.5σ(F). The mineral studied belongs to the family of layered titanosilicates, in which, unlike the sulfate-and phosphate-containing representatives of this family, the interlayer spaces are filled with carbonate groups.     

The Fe<Superscript>2+</Superscript>/Fe<Superscript>3+</Superscript> ratio in natural and heat-treated iron-rich eudialytes

The structures of natural iron-rich eudialyte (specimen 3458 from the Khibiny massif, the Kola Peninsula) and two heat-treated samples of this mineral calcined at 700 and 800°C were determined by X-ray diffraction. The trigonal unit-cell parameters (sp. gr. R3m) are as follows: a = 14.2645(1) Å, c = 29.9635(5) Å; a = 14.1307(1) Å, c = 30.1229(3) Å; a = 14.1921(2) Å, c = 30.2417(5) Å, respectively. It was found that Fe³⁺ ions in the calcined eudialytes, as well as impurities in the starting specimen, occupy the square-pyramidal Fe³⁺(V) sites, whereas Fe²⁺ ions are in the planar-tetragonal Fe²⁺(IV) sites.     

Refined structure of afwillite from the northern Baikal region

The crystal structure of the mineral afwillite [Ca₁₂(H₂O)₈][SiO₄]₄[SiO₂(OH)₂]₄ from the northern Baikal region was refined in a triclinic unit cell with the following parameters: a = 16.330(2) Å, b = 5.6389(6) Å, c = 11.685(1) Å, α = 90.08(1)°, β = 126.446(2)°, γ = 89.95(1)°, and sp. gr. P1. The triclinic unit cell is related to the monoclinic unit cell determined earlier (sp. gr. Cc, a = 16.278(1) Å, b = 5.6321(4) Å, c = 13.236(1) Å, and β = 134.898(3)°) by the transformation matrix [?100/010/101]. The structural model was determined using the phase-correction procedure and refined anisotropically to R = 2.8% based on 3270 independent reflections with F > 3σ(F). The crystal-chemical formula of afwillite was revised. The characteristic features of the IR spectrum of afwillite were explained based on the structural data.     

Single Crystal X-ray Diffraction Study of a Pure Natrolite Sample

The crystal structure of a pure natrolite sample, Na₂(Al₂Si₃O₁₀)·2H₂O, coming from Asheken, Ethiopia, has been analysed by single crystal X-ray diffraction. It crystallizes within the orthorhombic space group Fdd2, with the following cell constants: a = 18.2930(2) Å; b = 18.6430(5) Å; c = 6.5860(5) Å; V = 2246.07(18) Å³. The three-dimensional framework of this hydrated aluminosilicate zeolite is made up by chains of corner-sharing SiO₄ and AlO₄ tetrahedra down c; the chains are held together by sharing the external vertices of tetrahedra; water molecules and Na⁺ extra-framework cations fill up the resulting cavities, the latter forming irregular NaO₆ octahedra. Hydrogen bonds complete the array.