scholarly journals The Crystal Chemistry of Inorganic Hydroborates

Chemistry ◽  
2020 ◽  
Vol 2 (4) ◽  
pp. 805-826 ◽  
Author(s):  
Radovan Černý ◽  
Matteo Brighi ◽  
Fabrizio Murgia
Keyword(s):  
Crystal Structures ◽  
Crystal Chemistry ◽  
Inorganic Compounds ◽  
Close Packing ◽  
Crystal Data ◽  
Topology Analysis ◽  
Coordination Polyhedra ◽  
Anion Coordination ◽  
Simple Deformation ◽  
Crystal Structure Database

The crystal structures of inorganic hydroborates (salts and coordination compounds with anions containing hydrogen bonded to boron) except for the simplest anion, borohydride BH4−, are analyzed regarding their structural prototypes found in the inorganic databases such as Pearson’s Crystal Data [Villars and Cenzual (2015), Pearson’s Crystal Data. Crystal Structure Database for Inorganic Compounds, Release 2019/2020, ASM International, Materials Park, Ohio, USA]. Only the compounds with hydroborate as the only type of anion are reviewed, although including compounds gathering more than one different hydroborate (mixed anion). Carbaborane anions and partly halogenated hydroborates are included. Hydroborates containing anions other than hydroborate or neutral molecules such as NH3 are not discussed. The coordination polyhedra around the cations, including complex cations, and the hydroborate anions are determined and constitute the basis of the structural systematics underlying hydroborates chemistry in various variants of anionic packing. The latter is determined from anion–anion coordination with the help of topology analysis using the program TOPOS [Blatov (2006), IUCr CompComm. Newsl. 7, 4–38]. The Pauling rules for ionic crystals apply only to smaller cations with the observed coordination number within 2–4. For bigger cations, the predictive power of the first Pauling rule is very poor. All non-molecular hydroborate crystal structures can be derived by simple deformation of the close-packed anionic lattices, i.e., cubic close packing (ccp) and hexagonal close packing (hcp), or body-centered cubic (bcc), by filling tetrahedral or octahedral sites. This review on the crystal chemistry of hydroborates is a contribution that should serve as a roadmap for materials engineers to design new materials, synthetic chemists in their search for promising compounds to be prepared, and materials scientists in understanding the properties of novel materials.

The crystal chemistry of inorganic metal borohydrides and their relation to metal oxides

2015 ◽  
Vol 71 (6) ◽  
pp. 619-640 ◽  
Author(s):  
Radovan Černý ◽  
Pascal Schouwink
Keyword(s):  
Metal Oxides ◽  
Crystal Structures ◽  
Crystal Chemistry ◽  
Inorganic Compounds ◽  
Close Packing ◽  
Crystal Data ◽  
Topology Analysis ◽  
Coordination Polyhedra ◽  
Simple Deformation ◽  
Complex Anions

The crystal structures of inorganic homoleptic metal borohydrides are analysed with respect to their structural prototypes found amongst metal oxides in the inorganic databases such as Pearson's Crystal Data [Villars & Cenzual (2015). Pearson's Crystal Data. Crystal Structure Database for Inorganic Compounds, Release 2014/2015, ASM International, Materials Park, Ohio, USA]. The coordination polyhedra around the cations and the borohydride anion are determined, and constitute the basis of the structural systematics underlying metal borohydride chemistry in various frameworks and variants of ionic packing, including complex anions and the packing of neutral molecules in the crystal. Underlying nets are determined by topology analysis using the program TOPOS [Blatov (2006). IUCr CompComm. Newsl. 7, 4–38]. It is found that the Pauling rules for ionic crystals apply to all non-molecular borohydride crystal structures, and that the latter can often be derived by simple deformation of the close-packed anionic lattices c.c.p. and h.c.p., by partially removing anions and filling tetrahedral or octahedral sites. The deviation from an ideal close packing is facilitated in metal borohydrides with respect to the oxide due to geometrical and electronic considerations of the BH4 − anion (tetrahedral shape, polarizability). This review on crystal chemistry of borohydrides and their similarity to oxides is a contribution which should serve materials engineers as a roadmap to design new materials, synthetic chemists in their search for promising compounds to be prepared, and materials scientists in understanding the properties of novel materials.

Crystal chemistry of basic lead carbonates. III. Crystal structures of Pb3O2(CO3) and NaPb2(OH)(CO3)2

2000 ◽  
Vol 64 (6) ◽  
pp. 1077-1087 ◽  
Author(s):  
S. V. Krivovichev ◽  
P. C. Burns
Keyword(s):  
Crystal Structures ◽  
Direct Methods ◽  
Close Packing ◽  
Coordination Polyhedra ◽  
Electron Pairs ◽  
Oh Groups ◽  
Trigonal Prismatic Coordination ◽  
Lead Hydroxide ◽  
Hexagonal Sheets ◽  
Trigonal Prismatic

AbstractThe crystal structures of synthetic Pb3O2(CO3) and NaPb2(OH)(CO3)2, have been solved by direct methods and refined to R = 0.062 and 0.024, respectively. Pb3O2(CO3) is orthorhombic, Pnma, a = 22.194(3), b = 9.108(1), c = 5.7405(8) Å, V = 1160.4(3) Å3, Z = 8. There are four symmetrically distinct Pb2+ cations in irregular coordination polyhedra due to the effect of stereoactive s2 lone electron pairs. The structure is based upon double [O2Pb3] chains of [O(1)Pb4] and [O(2)Pb4] oxocentred tetrahedra and CO3 groups. The [O2Pb3] chains are parallel to the c axis, whereas the CO3 groups are parallel to the (010) plane. NaPb2(OH)(CO3)2 is hexagonal, P63mc, a = 5.276(1), c = 13.474(4)Å, V = 324.8(1) Å3, Z = 2 and has been solved by direct methods. There are two symmetrically distinct Pb2+ cations in asymmetric coordination polyhedra due to the effect of stereoactive s2 lone-electron pairs. The single symmetrically unique Na+ cation is in trigonal prismatic coordination. The structure is based on hexagonal sheets of Pb atoms. Within these sheets, Pb atoms are located at vertices of a 36 net, such that each Pb atom has six adjacent Pb atoms that are ~5.3 Å away. Two sheets are stacked in a close-packing arrangement, forming layers that contain the (CO3) groups. The layers are linked by OH groups that are linearly coordinated by two Pb2+ cations. Na+ cations are located between the layers. The structure is closely related to the structures of other lead hydroxide carbonates (leadhillite, macphersonite, susannite, hydrocerussite, ‘plumbonacrite’).

Mg5Pd10Si16 und Mg5Pt10Si16, Magnesium-Platinmetall-Silicide mit Tetraedern und gekappten Tetraedern aus Silicium-Atomen / Mg5Pd10Si16 and Mg5Pt10Si16, Magnesium Platinum Metal Silicides with Si4 Tetrahedra and Si12 Truncated Tetrahedra

2002 ◽  
Vol 57 (12) ◽  
pp. 1346-1352 ◽  
Author(s):  
Peter Lorenz ◽  
Walter Jung
Keyword(s):  
Boron Nitride ◽  
Single Crystal ◽  
Crystal Structures ◽  
Three Dimensional ◽  
Platinum Metal ◽  
Close Packing ◽  
Unit Cell ◽  
Crystal Data ◽  
Lattice Constants ◽  
Metal Silicides

The ternary silicides Mg5Pd10Si16 and Mg5Pt10Si16 have been prepared by reaction of magnesium with the binary platinum-metal silicides in sealed tantalum containers (Pt-compound: 1200°C, 3 d, up 20 °/h, down 5 °/h; Pd-compound: 1000°C, 2 d, up and down 50 °/h). In the case of the Pd-compound contact with the tantalum had to be avoided by using a boron nitride crucible. The isotypic compounds crystallize in the cubic space group F4̄3m with 4 formula units per unit cell. The crystal structures were determined from single crystal data, lattice constants from Guinier patterns. The following data were obtained: a = 1258.81(8) pm for Mg5Pd10Si16 and a = 1256.94(9) pm for Mg5Pt10Si16. Short distances in the three-dimensional platinum-metal silicon network indicate strong, covalent Pd(Pt)-Si-bonding (d(Pd-Si) = 240.2 to 256.1 pm; d(Pt-Si) = 237.1 to 258.5 pm). In addition, homonuclear bonding seems to be important, resulting in the formation of Si4-tetrahedra (d(Si-Si) = 250.4 pm (Mg5Pd10Si16) and 255 pm (Mg5Pt10Si16)), empty Si12-polyhedra with the shape of truncated tetrahedra (d(Si- Si): 234.5 and 248.2 pm (Mg5Pd10Si16); 236 and 248.2 pm (Mg5Pt10Si16)), and Mg-centered Pd(Pt)10-clusters with the shape of adamantane (d(Pd-Pd) = 282.3 pm; d(Pt-Pt) = 284.5 pm). Furthermore, Mg4-tetrahedra with Mg-Mg-distances of 360 pm are formed. The structure may be described by an expanded cubic “close” packing of MgPd(Pt)10-units in which the Si4-tetrahedra occupy the octahedral holes while the Si12-polyhedra and the Mg4-tetrahedra reside in one half of the tetrahedral holes each.

The pseudomalachite-ludjibaite-reichenbachite conundrum: OD description

2019 ◽  
Vol 57 (5) ◽  
pp. 571-581
Author(s):  
Emil Makovicky
Keyword(s):  
Crystal Structures ◽  
Current Knowledge ◽  
The Other ◽  
Crystal Chemical ◽  
Layer System ◽  
Coordination Polyhedra

Abstract Crystal structures of the three polymorphs of Cu5(PO4)2(OH)4, namely pseudomalachite, ludjibaite, and reichenbachite, can be described as being composed of rods perpendicular to their crystal-chemical layering. Two different sorts of rods can be defined. Type 1 rods share rows of Cu coordination polyhedra, forming a series of slabs. Slab boundaries and slab interiors represent alternating geometric OD layers of two kinds, with layer symmetries close to P21/m and , which make up two different stacking schemes of geometric OD layers in the structures of ludjibaite and pseudomalachite. Such OD layers, however, are not developed in reichenbachite. Type 2 rods are defined as having columns of PO4 tetrahedra in the corners of the rods. In the Type 2 slabs composed of these rods, geometric Pg OD layers of glide-arrayed tetrahedra alternate with more complex OD layers; in ludjibaite this system of layers is oriented diagonally with respect to the Type 1 OD layer system. Two different OD stackings of Type 2 OD layers form the ludjibaite and reichenbachite structures but not that of pseudomalachite. Thus, ludjibaite might form disordered intergrowths with either of the other two members of the triplet but reichenbachite and pseudomalachite should not form oriented intergrowths. Current knowledge concerning formation of the three polymorphs is considered.

scholarly journals Classification of apatite structures via topological data analysis: a framework for a ‘Materials Barcode’ representation of structure maps

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Scott Broderick ◽  
Ruhil Dongol ◽  
Tianmu Zhang ◽  
Krishna Rajan
Keyword(s):  
Machine Learning ◽  
Data Analysis ◽  
Crystal Chemistry ◽  
Persistent Homology ◽  
Hierarchical Classification ◽  
Topological Data Analysis ◽  
Learning Tool ◽  
Coordination Polyhedra ◽  
Machine Learning Tool ◽  
Topological Data

AbstractThis paper introduces the use of topological data analysis (TDA) as an unsupervised machine learning tool to uncover classification criteria in complex inorganic crystal chemistries. Using the apatite chemistry as a template, we track through the use of persistent homology the topological connectivity of input crystal chemistry descriptors on defining similarity between different stoichiometries of apatites. It is shown that TDA automatically identifies a hierarchical classification scheme within apatites based on the commonality of the number of discrete coordination polyhedra that constitute the structural building units common among the compounds. This information is presented in the form of a visualization scheme of a barcode of homology classifications, where the persistence of similarity between compounds is tracked. Unlike traditional perspectives of structure maps, this new “Materials Barcode” schema serves as an automated exploratory machine learning tool that can uncover structural associations from crystal chemistry databases, as well as to achieve a more nuanced insight into what defines similarity among homologous compounds.

Crystal structures of tricalcium citrates

2018 ◽  
Vol 33 (2) ◽  
pp. 98-107 ◽  
Author(s):  
James A. Kaduk
Keyword(s):  
Crystal Structures ◽  
Density Functional ◽  
Three Dimensional ◽  
Water Molecules ◽  
Calcium Citrate ◽  
Powder Diffraction Data ◽  
Coordination Polyhedra ◽  
X Ray ◽  
Calcium Supplements ◽  
Dimensional Network

The crystal structures of calcium citrate hexahydrate, calcium citrate tetrahydrate, and anhydrous calcium citrate have been solved using laboratory and synchrotron X-ray powder diffraction data, and optimized using density functional techniques. Both the hexahydrate and tetrahydrate structures are characterized by layers of edge-sharing Ca coordination polyhedra, including triply chelated Ca. An additional isolated Ca is coordinated by water molecules, and two uncoordinated water molecules occur in the hexahydrate structure. The previously reported polymorph of the tetrahydrate contains the same layers, but only two H2O coordinated to the isolated Ca and two uncoordinated water molecules. Anhydrous calcium citrate has a three-dimensional network structure of Ca coordination polyhedra. The new polymorph of calcium citrate tetrahydrate is the major crystalline phase in several commercial calcium supplements.

Strukturen der mehrkernigen nickelthiolato-komplexe [(μ-SMe)2(Ni(MeNHCS2))2] und cyclo-[(μ-SMe)2Ni]6 / Structures of Two Polynuclear Nickel-Thiolato-Complexes [(μ-SMe)2(Ni(MeNHCS2))2] and cyclo-[(μ-SMe)2Ni]6

1994 ◽  
Vol 49 (6) ◽  
pp. 770-772 ◽  
Author(s):  
Klaus Schulbert ◽  
Rainer Mattes
Keyword(s):  
Crystal Structures ◽  
Nickel Acetate ◽  
Monoclinic Space Group ◽  
Crystal Data ◽  
Orthorhombic Space Group ◽  
Space Group ◽  
Dithiocarbamic Acid ◽  
Coordination Spheres ◽  
Partial Degradation ◽  
Acid Esters

The reactions of N-substituted dithiocarbamic acid esters and nickel acetate yield, by partial degradation of the esters, the polynuclear nickel thiolato complexes cyclo-[(μ-SMe)2Ni]6, 1 and [(μ-SMe)2(Ni(MeNHCS2))2, 2. Their crystal structures have been determined. The Ni coordination spheres are comprised of four sulfur atoms in a planar arrangement. 1 is a second, highly symmetrical modification of the already known cyclic hexamer Ni6(SMe)12. In 2 two Ni(PhNHCS2) moieties are bridged to dimers by thiolato groups. Two of these dimers are connected to a tetramer by weak axial Ni-S interactions. Crystal data for 1: monoclinic, space group P21/n, a = 986.1(2), b = 1308.1(3), c = 1228.6(2) pm, β = 96.07(3)°, Z = 2, R = 0.072, Rw = 0.062, 3797 reflections. 2: orthorhombic, space group Pnma, a = 1790.0(4), b = 1806.7(4), c = 934.4(2) pm. Z = 4, R = 0.061, Rw = 0.051, 2079 reflections

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