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The reaction of W6Br12 with AgBr in evacuated silica tubes (temperature gradient 925 K/915 K) yielded brownish black octahedra of Ag[W6Br14] (I) and yellowish green platelets of Ag2[W6Br14] (II) both in the low temperature zone. (I) crystallizes cubically (Pn3 (no. 201); a = 13.355 Å, Z = 4) and (II) monoclinically (P21/c (no. 14); a = 9.384 Å, b = 15.383 Å, c = 9.522 Å, β = 117.34°, Z = 2). Both crystal structures contain isolated cluster anions, namely [(W6Bri8)Bra6]1– and [(W6Bri8)Bra6])]2–, respectively, with the mean distances and angles: (I) d(W–W) = 2.648 Å, d(W–Bri) = 2.617 Å, d(W–Bra) = 2.575 Å, d(Bri…Bri) = 3.700 Å, d(Bri…Bra) = 3.692 Å, ∠W–Bri–W = 60.78°. (II) d(W–W) = 2.633 Å, d(W–Bri) = 2.624 Å, d(W–Bra) = 2.613 Å, d(Bri…Bri) = 3.710 Å, d(Bri…Bra) = 3.707 Å, ∠W–Bri–W = 60.23°. The Ag+ cations are trigonal antiprismatically coordinated in (I) with d(Ag–Br) = 2.855 Å, but distorted trigonally planar in (II) with d(Ag–Br) = 2.588–2.672 Å. The structural details of hitherto known compounds with [W6Br14] anions will be discussed. Die Clusterverbindungen Ag[W6Br14] und Ag2[W6Br14] Bei der Umsetzung von W6Br12 mit AgBr in evakuierten Quarzglasampullen (Temperaturgradient 925 K/915 K) entstehen in der kalten Zone nebeneinander schwarzbraune Oktaeder von Ag[W6Br14] (I) und gelbgrüne Blättchen von Ag2[W6Br14] (II). (I) kristallisiert kubisch (Pn3 (Nr. 201); a = 13.355 Å, Z = 4) und (II) monoklin (P21/c (Nr. 14); a = 9.384 Å, b = 15.383 Å, c = 9.522 Å, β = 117.34°, Z = 2). Die Kristallstrukturen enthalten die isolierten Clusteranionen [(W6Bri8)Bra6]1– bzw. [(W6Bri8)Bra6])]2–, mit den mittleren Abständen und Winkeln: (I) d(W–W) = 2.648 Å, d(W–Bri) = 2.617 Å, d(W–Bra) = 2.575 Å, d(Bri…Bri) = 3.700 Å, d(Bri…Bra) = 3.692 Å, ∠W–Bri–W = 60.78°. (II) d(W–W) = 2.633 Å, d(W–Bri) = 2.624 Å, d(W–Bra) = 2.613 Å, d(Bri…Bri) = 3.710 Å, d(Bri…Bra) = 3.707 Å, ∠W–Bri–W = 60.23°. Die Ag+-Kationen sind in (I) trigonal-antiprismatisch koordiniert mit d(Ag–Br) = 2.855 Å, in (II) verzerrt trigonal-planar mit d(Ag–Br) = 2.588–2.672 Å. Die strukturellen Einzelheiten der bisher bekannten Verbindungen mit [W6Br14]-Anionen werden diskutiert.The crystal structure of monoclinic magnesium astrophyllite has been redetermined. The samples were from Khibina alkaline massifs, Russia. K 2 NaNa(Fe,Mn) 4 Mg 2 Ti 2 [Si 4 O 12 ] 2 (OH) 4 (OH,F) 2 , M r = 1202.31, monoclinic, A 2, a = 10.370 (3), b = 23.129 (5), c = 5.322 (1) Å, β = 99.55 (2)°, V = 1258.8 (5) Å 3 , Z = 2, D x = 3.173 Mg m −3 , Mo K α, λ = 0.71069 Å, μ = 3.74 mm −1 , F (000) = 1179, T = room temperature, R = 0.057 for 1720 reflections. The determination indicated that the coordination number of Ti is five. In tetrahedra of astrophyllite the open-branched Si—O chain connected with Ti—O semi-octahedra by corner-sharing formed a continuous sheet. Na atoms have two types of coordination. Their coordination numbers are eight and six. The Na atoms with coordination number eight are situated between layers. Other types of Na atoms are situated within the layers and form Na—O octahedra with partial occupancies.
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Abstract The crystal structure of kintoreite, PbFe 3 (PO 4 ) 2 (OH,H 2 O) 6 , has been refined. The mineral is rhombohedral, R m with a = 7.3310(7), c = 16.885(2) Å, Z = 3; the structure has been refined to R = 3.0% and R w = 3.0% using 183 observed reflections [I > 2σ(I)]. Kintoreite has the alunite-type structure which consists of sheets of corner-sharing Fe(O,OH) 6 octahedra parallel to (001). The sheets are composed of clusters of three corner-linked octahedra which are tilted so that the three apical O atoms form the base of the X O 4 tetrahedra. The clusters of octahedra are linked to similar groups by corner-sharing to form six membered rings. The Pb cations occupy the cavities between pairs of octahedral sheets and are surrounded by six oxygen atoms from the tetrahedra and six oxygen atoms from the octahedra to form a very distorted icosahedron. The mean bond lengths for the various coordination polyhedra are X –O 1.55 Å, ( X = P, As, S); Fe–(O, OH) 2.01 Å; Pb–O 2.84 Å. The composition of the crystal used in the refinement was PbFe 3 (PO 4 ) 1.3 (AsO 4 ) 0.4 (SO 4 ) 0.3 (OH,H 2 O) 6 . The X O 4 anions are disordered, as in beudantite, rather than being ordered, as they are claimed to be in corkite.
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Abstract [Fe(μ-Cl)2(phen)] n (1) and [Fe(H2O)3(phen)SO4] (2) have been synthesized and characterized by single crystal X-ray diffraction analysis, IR and UV spectra. Complex 1 crystallizes in monoclinic system with space group of C 2/c and 2 crystallizes in monoclinic system with space group of P 21/c. The structure of 1 shows that each Fe(II) coordinates with one phen and four chlorides forming a distorted octahedral environment, and [Fe(μ-Cl)2(phen)] as a repeating unit forms a one-dimensional chain. The structure of 2 shows that each Fe(II) coordinates with one , one 1,10-phen and three H2O molecules; the crystal architecture is stabilized by hydrogen bonds and π–π interactions. Keywords: Iron1,10-Phenanthroline1D chainπ–π Stacking interaction Acknowledgements We gratefully acknowledge the financial support of the Beijing Natural Science Foundation (20052007), which made this work possible.
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The title compound, potassium pentanickel hexaborophosphate tridecahydroxide, was synthesized under hydrothermal conditions from the NiCl(2)-K(3)PO(4)-B(2)O(3)-K(2)CO(3)-H(2)O system. The crystal structure was determined using single-crystal X-ray diffraction at 100 K. The KNi(5)[P(6)B(6)O(23)(OH)(13)] phase is cubic. For the three crystallographically distinct Ni centers, two occupy sites with 3 symmetry, while the third Ni and the K atom are located on 3 sites. The structure is built from alternating borate and phosphate tetrahedra forming 12-membered puckered rings with K(+) ions at the centers. These rings are arranged as in cubic dense sphere packing. A novel feature of the new crystal structure is the presence of linear trimers of face-sharing [NiO(6)] octahedra occupying the octahedral interstices of this sphere packing, and of single [NiO(6)] octahedra in the tetrahedral interstices. All oxygen corners of the Ni octahedra are linked to phosphate or borate tetrahedra of the 12-membered rings to form a mixed anionic framework.
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The crystallization of a new allotrope of cyclo-octaselenium, named γ-monoclinic selenium, from a solution of dipiperidinotetraselane in carbon disulphide is described. The allotrope γ-Se8 crystallizes in space group P21/c(no. 14) with a= 15.018(1), b= 14.713(1), c= 8.789(1)Å, β= 93.61(1)°, and z= 64 (atoms). The crystal structure has been determined by X-ray diffraction from Mo-Kα diffractometer data and refined to R 0.047 for 2 525 observed reflections. There are two crown-shaped Se8 rings in the asymmetric unit, with bond lengths, bond angles, and dihedral angles in the ranges 2.326(3)–2.344(3)Å, 103.3(1)–109.1(1)°, and 96.5–107.2° respectively. The overall averages, 2.334 ± 0.005 Å, 105.8 ± 1.4°, and 101.1 ± 2.2°, are the same, within error limits, as in α- and β-monoclinic selenium. There are more short contacts between the rings than in the α and β forms, the shortest ones being 3.346(3) and 3.404(3)Å.
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