The synthetic cobalt vanadium selenite, Co?V?Se?O??.
ABSTRACT: The crystal structure of dicobalt(II) divanadium(V) disel-enium(IV) undeca-oxide, Co?V?Se?O??, exhibits a three-dimensional framework, the building units being distorted CoO? octa-hedra and VO? square pyramids arranged so as to form alternate chains along . The framework has channels along  and  in which the two ?-SeO?E (site symmetries m; E being the 4s² lone electron pair of Se(IV)) tetra-hedra reside and connect to the other building blocks. The structure contains corner- and edge-sharing CoO? octa-hedra, corner- and edge-sharing VO? square pyramids and edge-sharing ?-SeO?E tetra-hedra. Co?V?Se?O?? is the first oxide containing all the cations Co(II), V(V) and Se(IV).
Project description:The title compound, Na(2)Cu(3)(SeO(3))(4)(H(2)O)(4), has been prepared under hydro-thermal conditions. The crystal structure contains a three-dimensional anionic framework made up from distorted [CuO(4)(H(2)O)(2)] octa-hedra ( symmetry), [CuO(4)(H(2)O)] square pyramids and trigonal-pyramidal SeO(3) units sharing common corners. The connectivity among these units leads to four- and eight-membered polyhedral rings, which by edge-sharing inter-connect into walls. A rhombus-like 16-membered polyhedral ring channel system with a longest length of approximately 14.0?Å and a shortest length of 5.3?Å is enclosed by such walls along the a axis. The water mol-ecules attached to the Cu atoms, as well as the electron lone pairs of the Se(IV) atoms, protrude into these channels. The seven-coordinated Na(+) counter-cations occupy the remaining free space of the 16-membered polyhedral ring channels. An intricate network of O-H?O hydrogen bonds further consolidates the three-dimensional structure.
Project description:In an attempt to hydro-thermally synthesize a phase with composition Co(2)Cu(PO(4))(2)·H(2)O, we obtained the title compound, Co(2.39)Cu(0.61)(PO(4))(2)·H(2)O instead. Chemical analysis confirmed the presence of copper in the crystal. The crystal structure of the title compound can be described as a three- dimensional network constructed from the stacking of two types of layers extending parallel to (010). These layers are made up from more or less deformed polyhedra: CoO(6) octa-hedra, (Cu/Co)O(5) square pyramids and PO(4) tetra-hedra. The first layer is formed by pairs of edge-sharing (Cu/Co)O(5) square pyramids linked via a common edge of each end of the (Cu/Co)(2)O(8) dimer to PO(4) tetra-hedra. The second layer is undulating and is built up from edge-sharing CoO(6) octa-hedra. The linkage between the two layers is accomplished by PO(4) tetra-hedra. The presence of water mol-ecules in the CoO(4)(H(2)O)(2) octa-hedron also contributes to the cohesion of the layers through O-H?O hydrogen bonding.
Project description:A new potassium vanadium arsenate, tripotassium trivanadium bis-(arsenate) hexa-oxide, K(3)VO(2)(V(2)As(2)O(12)), was synthesized by a solid-state reaction at 743?K. The structure is built up from VO(5) pyramids, VO(4) tetra-hedra (.m. symmetry) and AsO(4) tetra-hedra linked together by corner-sharing to form a three-dimensional framework. The two crystallographically independent K(+) cations, one of which has .m. symmetry, are located in the inter-connected tunnels running along the a and b directions.
Project description:Single crystals of Ni3(TeO(OH)2)2(PO4)2, trinickel(II) bis[(oxidodihydoxidotellurate(IV)] bis(phosphate),were obtained by hydro-thermal synthesis at 483?K, starting from NiCO3·2Ni(OH)2, TeO2 and H3PO4 in a molar ratio of 1:2:2. The crystal structure of Ni3Te2O2(PO4)2(OH)4 is isotypic with that of Co3Te2O2(PO4)2(OH)4 [Zimmermann et al. (2011 ?). J. Solid State Chem. 184, 3080-3084]. The asymmetric unit comprises two Ni (site symmetries , 2/m) one Te (m), one P (m), five O (three m, two 1) and one H (1) sites. The tellurium(IV) atom shows a coordination number of five, with the corresponding [TeO3(OH)2] polyhedron having a distorted square-pyramidal shape. The two NiII atoms are both octa-hedrally coordinated but form different structural elements: one constitutes chains made up from edge-sharing [NiO6] octa-hedra extending parallel to , and the other isolated [NiO2(OH)4] octa-hedra. The two kinds of nickel/oxygen octa-hedra are connected by the [TeO3(OH)2] pyramids and the [PO4] tetra-hedra through edge- and corner-sharing into a three-dimensional framework structure with channels extending parallel to . Hydrogen bonds of medium strength between the hy-droxy groups and one of the phosphate O atoms consolidate the packing. A qu-anti-tative structure comparison between Ni3Te2O2(PO4)2(OH)4 and Co3Te2O2(PO4)2(OH)4 is made.
Project description:Pb(6)Co(9)(TeO(6))(5), hexa-lead(II) nona-cobalt(II) penta-tellur-ate(VI), is isotypic with its nickel(II) analogue. The asymmetric unit contains two Pb atoms (site symmetries .2., ..2), four Co atoms (..2, ..2, 3.., 3.2) two Te atoms (..2, 3..) and six O atoms (all in general positions), with the Te and Co sites in octa-hedral coordination environments. The crystal structure can be subdivided into two types of layers parallel to (001). The first layer at z ? 0.25 is made up of edge-sharing [CoO(6)] and [TeO(6)] octa-hedra, with 1/6 of the octa-hedral holes not occupied. The second layer, situated at z ? 0, consist of an alternating arrangement of Pb(II) atoms and of double octa-hedra that are made up from face-sharing [CoO(6)] and [TeO(6)] octa-hedra. The two types of layers are linked together through corner-sharing of [CoO(6)] and [TeO(6)] octa-hedra. The Pb(II) atoms are situated in the cavities of the framework and are stereochemically active with one-sided - and -coordinations, respectively.
Project description:The vanadium oxide arsenate with formula K?V?O?(AsO?)?, dipotassium divanadium(IV) dioxide diarsenate, has been synthesized by solid-state reaction in an evacuated silica ampoule. Its structure is isotypic with K?V?O?(PO?)?. The framework is built up from corner-sharing VO? octa-hedra and AsO? tetra-hedra, creating an infinite [VAsO?](?) chain running along the a- and c-axis directions. The K? cations are located in hexa-gonal tunnels, which are delimited by the connection of the [VAsO?](?) chains.
Project description:Agardite-(Y), with a refined formula of Cu(2+) 5.70(Y0.69Ca0.31)[(As0.83P0.17)O4]3(OH)6·3H2O [ideally Cu(2+) 6Y(AsO4)3(OH)6·3H2O, hexa-copper(II) yttrium tris-(arsenate) hexa-hydroxide trihydrate], belongs to the mixite mineral group which is characterized by the general formula Cu(2+) 6 A(TO4)3(OH)6·3H2O, where nine-coordinated cations in the A-site include rare earth elements along with Al, Ca, Pb, or Bi, and the T-site contains P or As. This study presents the first structure determination of agardite-(Y). It is based on the single-crystal X-ray diffraction of a natural sample from Jote West mine, Pampa Larga Mining District, Copiapo, Chile. The general structural feature of agardite-(Y) is characterized by infinite chains of edge-sharing CuO5 square pyramids (site symmetry 1) extending down the c axis, connected in the ab plane by edge-sharing YO9 polyhedra (site symmetry -6..) and corner-sharing AsO4 tetra-hedra (site symmetry m..). Hy-droxyl groups occupy each corner of the CuO5-square pyramids not shared by a neighboring As or Y atom. Each YO9 polyhedron is surrounded by three tubular channels. The walls of the channels, parallel to the c axis, are six-membered hexa-gonal rings comprised of CuO5 and AsO4 polyhedra in a 2:1 ratio, and contain free mol-ecules of lattice water.
Project description:The vanadyl arsenate, VOAsO(4), has been isolated by a solid-state reaction. The structure consists of distorted VO(6) octa-hedra and AsO(4) tetra-hedra sharing corners to build up VAsO(7) layers parallel to ac linked by edge-sharing of VO(6) octa-hedra, forming a three-dimensional framework.
Project description:The title compound, BaMnSnSe(4), was obtained by reaction of the elements at 1123?K in an evacuated silica tube. It adopts the BaCdSnS(4) structure type, which is a variant of the SrIn(2)Se(4) structure type. Its structure consists of distorted edge-sharing tetra-hedra, alternating with Mn and Sn atoms as central atom. These [MnSnSe(6)] units display corner sharing, forming stacked infinite layers in the ac plane. The three different Ba(2+) atoms are located between the [MnSnSe(6)] layers, two on twofold rotation axes, and exhibit distorted square-antiprismatic coordinations.
Project description:The structural properties of cobalt phosphides were investigated at high pressures and temperatures to better understand the behavior of metal-rich phosphides in Earth and planetary inter-iors. Using single-crystal X-ray diffraction synchrotron data and a laser-heated diamond anvil cell, we discovered a new high pressure-temperature (HP-HT) cobalt phosphide, Co12P7, dodeca-cobalt hepta-phosphide, synthesized at 27?GPa and 1740?K, and at 48?GPa and 1790?K. Co12P7 adopts a structure initially proposed for Cr12P7 (space-group type P , Z =1), consisting of chains of edge-sharing CoP5 square pyramids and chains of corner-sharing CoP4 tetra-hedra. This arrangement leaves space for trigonal-prismatic channels running parallel to the c axis. Coupled disordering of metal and phospho-rus atoms has been observed in this structure for related M 12P7 (M = Cr, V) compounds, but all Co and P sites are ordered in Co12P7. All atomic sites in this crystal structure are situated on special positions. Upon decompression to ambient conditions, peak broadening and loss of reflections at high angles was observed, suggesting phase instability.