Coordination Polyhedra of AnTen (An = Th, U, Np, Pu, Am, or Cm) in Crystal Structures

2021 ◽  
Vol 95 (10) ◽  
pp. 2096-2106
Author(s):  
V. N. Serezhkin ◽  
M. Albakajaji ◽  
L. B. Serezhkina
Keyword(s):  
Crystal Structures ◽  
Coordination Polyhedra

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.

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.

The coordination polyhedra CdS n in crystal structures

2008 ◽  
Vol 34 (5) ◽  
pp. 388-393
Author(s):  
V. N. Serezhkin ◽  
D. V. Pushkin ◽  
V. A. Isaev ◽  
A. G. Avanesov
Keyword(s):  
Crystal Structures ◽  
Coordination Polyhedra

Coordination Polyhedra MC n (M Is s-Metal Atom) in Crystal Structures

2018 ◽  
Vol 63 (3) ◽  
pp. 324-332
Author(s):  
M. O. Karasev ◽  
I. N. Karaseva ◽  
D. V. Pushkin
Keyword(s):  
Crystal Structures ◽  
Metal Atom ◽  
Coordination Polyhedra

scholarly journals Crystal structures of potassium trifluorido(4-methoxyphenyl)borate and potassium trifluorido(4-fluorophenyl)borate

2014 ◽  
Vol 70 (8) ◽  
pp. 68-71 ◽  
Author(s):  
William T. A. Harrison ◽  
James L. Wardell
Keyword(s):  
Crystal Structures ◽  
Coordination Polyhedra ◽  
Space Groups ◽  
Molecular Salts

The title compounds, K+·C7H7BF3O−, (I), and K+·C6H4BF4−, (II), are molecular salts containingpara-substituted phenyltrifluoridoborate anions. In each compound, the B atom adopts a distorted tetrahedral BCF3geometry. Despite their different compositions and space groups, the irregular KF8coordination polyhedra of the potassium cations in the structures are almost identical. These polyhedra share faces and edges, generating infinite (010) layers in (I) and infinite (001) layers in (II). In (I), adjacent layers are stacked in anAAA… fashion, whereas in (II), they are stacked in anABAB… sequence.

Coordination Polyhedra LnO n (Ln = Tb, Dy, Ho) in Crystal Structures

2005 ◽  
Vol 31 (11) ◽  
pp. 814-822
Author(s):  
A. V. Vologzhanina ◽  
D. V. Pushkin ◽  
V. N. Serezhkin
Keyword(s):  
Crystal Structures ◽  
Coordination Polyhedra

The coordination polyhedra GaS n in crystal structures

2008 ◽  
Vol 34 (4) ◽  
pp. 295-300
Author(s):  
V. N. Serezhkin ◽  
V. A. Isaev ◽  
A. G. Avanesov ◽  
D. V. Pushkin ◽  
E. V. Peresypkina
Keyword(s):  
Crystal Structures ◽  
Coordination Polyhedra

scholarly journals Crystal structures of two magnesium citrates from powder diffraction data

2020 ◽  
Vol 76 (10) ◽  
pp. 1611-1616
Author(s):  
James A. Kaduk
Keyword(s):  
Crystal Structures ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Density Functional ◽  
Powder Diffraction Data ◽  
Magnesium Citrate ◽  
Coordination Polyhedra ◽  
X Ray ◽  
Cation Coordination ◽  
Citrate Anion

The crystal structures of magnesium hydrogen citrate dihydrate, Mg(HC6H5O7)(H2O)2, (I), and bis(dihydrogen citrato)magnesium, Mg(H2C6H5O7)2, (II), have been solved and refined using synchrotron X-ray powder diffraction data, and optimized using density functional techniques. In (I), the citrate anion occurs in the trans, trans-conformation, and triply chelates to the Mg cation. In (II), the citrate anion is trans, gauche, and doubly chelates to the Mg cation. In both compounds the Mg cation coordination polyhedron is an octahedron. In (I), the MgO6 coordination polyhedra are isolated, while in (II), they share edges to form chains. Strong O—H...O hydrogen bonds are prominent in the two structures, as well as in the previously reported magnesium citrate decahydrate.

AnSn Coordination Polyhedra (An = Th, U, Np, Pu, Am, Cm, or Cf) in Crystal Structures

2020 ◽  
Vol 62 (6) ◽  
pp. 689-699
Author(s):  
V. N. Serezhkin ◽  
M. Albakajaji ◽  
L. B. Serezhkina
Keyword(s):  
Crystal Structures ◽  
Coordination Polyhedra

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’).

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