Crystal chemistry of basic lead carbonates. I. Crystal structure of synthetic shannonite, Pb2O(CO3)

2000 ◽  
Vol 64 (6) ◽  
pp. 1063-1068 ◽  
Author(s):  
S. V. Krivovichev ◽  
P. C. Burns
Keyword(s):  
Crystal Structure ◽  
Crystal Chemistry ◽  
Direct Methods ◽  
Coordination Polyhedra ◽  
Form Complex ◽  
Electron Pairs ◽  
3 Dimensional

AbstractThe crystal structure of synthetic shannonite, Pb2O(CO3), orthorhombic, P212121, a = 5.1465(7), b = 9.014(1), c = 9.315(1)Å, V = 432.12(10)Å3, Z = 4, has been solved by direct methods and refined to R = 0.054. There are two symmetrically distinct Pb2+ cations in irregular coordination polyhedra due to the effect of stereoactive s2 lone-electron pairs. The structure can be described as composed of chains of [OPb2] composition running parallel to [100] that are built by corner-sharing of OPb3 oxocentred triangles. The [OPb2] chains are surrounded by CO3 groups to form complex [OPb2](CO3) chains that are linked into a 3-dimensional framework by additional Pb–O bonds. The structure has channels that are parallel to [100] in which the lone-electron pairs of the Pb2+ cations are probably located.

Crystal chemistry of basic lead carbonates. II. Crystal structure of synthetic ‘plumbonacrite’

2000 ◽  
Vol 64 (6) ◽  
pp. 1069-1075 ◽  
Author(s):  
S. V. Krivovichev ◽  
P. C. Burns
Keyword(s):  
Crystal Structure ◽  
Crystal Chemistry ◽  
Direct Methods ◽  
Coordination Polyhedra ◽  
Electron Pairs ◽  
Hydroxo Complexes ◽  
Aqueous Environments ◽  
Structural Subunit

AbstractThe crystal structure of synthetic ‘plumbonacrite’, Pb5O(OH)2(CO3)3, hexagonal, P63cm, a = 9.0921(7), c = 24.923(3)Å, V = 1784.3(3)Å3, Z = 6, has been solved by direct methods and refined to R = 0.049. There are six symmetrically independent Pb2+ positions in the structure, the coordination polyhedra of which are strongly distorted due to the effect of s2 lone-electron pairs on the Pb2+ cations. The Pb(6) position is disordered with a Pb–Pb distance of 1.24 Å . The structure of ‘plumbonacrite’ is built from complex Pb–O layers parallel to the (001) plane similar to those observed in polymorphs of Pb4(OH)2(SO4)(CO3)2. The structure of these layers can be described in terms of Pb–O,OH motifs and CO3 groups. The smallest structural subunit is the oxocentred [OPb4] tetrahedron that shares three of its Pb-Pb edges with three [(OH)Pb3] distorted triangles to form [O(OH)3Pb7] clusters. These clusters are surrounded by CO3 groups, forming more complex clusters. Due to the disorder in the Pb(6) site, the clusters comprising this site are linked with each other via OH(10) groups to give continuous sheets of Pb–O,OH bonds which are parallel to the (001) plane. The [O(OH)3Pb7] clusters in ‘plumbonacrite’ may be important in more complex Pb carbonate oxo/hydroxo complexes that may exist in aqueous environments.

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’).

Crystal Structure of the Ternary Compound Sc6Cu24.1Al11.9

2016 ◽  
Vol 257 ◽  
pp. 26-29 ◽  
Author(s):  
Nastasia Klymentiy ◽  
Nataliya Semuso ◽  
Svitlana Pukas ◽  
Yaroslav O. Tokaychuk ◽  
Lev Akselrud ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Direct Methods ◽  
The Body ◽  
Powder Diffraction Data ◽  
Coordination Polyhedra ◽  
X Ray ◽  
Pearson Symbol ◽  
Icosahedral Clusters

The crystal structure of a new ternary aluminide of refined composition Sc6Cu24.1(2)Al11.9(2) was solved by direct methods from X-ray powder diffraction data. It belongs to the cubic space group Im-3, Pearson symbol cI176-8, a = 13.5337(5) Å. The structure of Sc6Cu24.1Al11.9 may be described as a packing of 16-vertex coordination polyhedra of the Sc atoms, which form icosahedral clusters around the origin and the center of the body-centered unit cell. The voids at the centers of the clusters are filled by Cu4 tetrahedra, disordered between two possible orientations. The structure is closely related to the structure types Ru3Be17 and Ce6Au27.6Sn6.8.

The crystal structure of Pb5(As3+O3)Cl7 from the historic slags of Lavrion, Greece – a novel Pb(II) chloride arsenite

2011 ◽  
Vol 75 (2) ◽  
pp. 337-345 ◽  
Author(s):  
O. I. Siidra ◽  
S. V. Krivovichev ◽  
N. V. Chukanov ◽  
I. V. Pekov ◽  
A. Magganas ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Direct Methods ◽  
Structural Features ◽  
Lead Chloride ◽  
Form Complex ◽  
Trigonal Pyramid

AbstractThe crystal structure of new lead chloride arsenite, Pb5(As3+O3)Cl7 [orthorhombic, Pbcn, a = 16.894(2), b = 10.913 (1), c = 16.760(2) Å, V = 3090.1(7) Å3], from the historic slags of Lavrion, Greece, has been solved by direct methods and refined to R1 = 0.069. The structure contains five symmetrically unique Pb, one As, eight Cl and three O sites. The As atom forms three nearly equal As—O bonds which result in the formation of an AsO3 trigonal pyramid with As at the apex. The Pbl. Pb2, Pb3 and Pb4 atoms are bonded to the AsO3 groups via Pb2+—O bonds to form complex [Pb4(AsO3)] chains parallel to the b axis. The Pb(5) atom is coordinated solely by Cl– anions. The resulting Pb(5)Cl7 polyhedra share common edges and corners to produce bent chains parallel to the c axis. A short compilation of structural features of known lead chloride arsenites is given.

Chloroxiphite Pb3CuO2(OH)2Cl2: structure refinement and description in terms of oxocentred OPb4 tetrahedra

2008 ◽  
Vol 72 (3) ◽  
pp. 793-798 ◽  
Author(s):  
O. I. Siidra ◽  
S. V. Krivovichev ◽  
R. W. Turner ◽  
M. S. Rumsey
Keyword(s):  
Crystal Structure ◽  
Structural Unit ◽  
Structure Refinement ◽  
Modular Structure ◽  
Coordination Polyhedra ◽  
Electron Pairs ◽  
Large Size ◽  
The Difference ◽  
Strong Distortion

AbstractThe crystal structure of chloroxiphite, Pb3CuO2(OH)2Cl2, from Merehead Quarry (monoclinic, P21/m, a = 6.6972(8), b = 5.7538(5), c = 10.4686(14) Å,β = 97.747(10)°, V = 399.72(8) Å3) has been refined to R1 = 0.041. The structure contains three symmetrically unique Pb sites and one Cu site. The strong distortion of the Pb2+ coordination polyhedra is due to the stereoactivity of the s2 lone electron pairs on the Pb2+ cations. The Cu-site is coordinated by four OH- groups to form an almost planar Cu(OH)4 square that is complemented by two apical Cl– anions, forming an elongated [Cu(OH)4Cl2] octahedron. Because of the large size and variability of coordination polyhedra around Pb2+ cations and the strength of the Me–O bonds in comparison to the Me–Cl bonds (Me = metal), it is convenient to describe the structure of chloroxiphite in terms of oxocentred OPb4 tetrahedra. The O1 atom is tetrahedrally coordinated by four Pb2+ cations forming relatively short and strong O–Pb bonds. The OPb4 tetrahedra link together via common edges to form [O2Pb3]2+ double chains. The difference between chloroxiphite and other natural oxyhalides is the presence of Cu2+ cations which form an independent structural unit that links to units formed by OPb4 tetrahedra. In this sense, chloroxiphite can be considered as a modular structure consisting of both strong cation- and anion-centred units.

The crystal structure and chemical composition of cumengéite

1986 ◽  
Vol 50 (355) ◽  
pp. 157-162 ◽  
Author(s):  
F. C. Hawthorne ◽  
L. A. Groat
Keyword(s):  
Crystal Structure ◽  
Chemical Composition ◽  
Least Squares ◽  
Direct Methods ◽  
Unit Cell ◽  
Trigonal Prism ◽  
Diverse Range ◽  
Coordination Polyhedra ◽  
Space Group

AbstractThe crystal structure of cumengéite, Pb21Cu20Cl42(OH)40, tetragonal, a= 15.065(2), c= 24.436(5) Å, V = 5546(2) Å3, space group I4/mmm, Z = 2, has been solved by direct methods and refined by least-squares to an R index of 7.1 % for 1158 observed (I > 2.5σ I) reflections. The cumengéite structure shows a very diverse range of cation coordinations. There are five distinct Pb sites with the following coordination polyhedra: octahedron, square antiprism, augmented trigonal prism, a very distorted biaugmented trigonal prism and a fairly regular biaugmented trigonal prism, the latter being only half-occupied; there are two distinct Cu sites with octahedral and square pyramidal coordination respectively. The coordination polyhedra share elements to form prominent columns or rods of polyhedra parallel to the c-axis and centred on the 4-fold axes of the unit cell. These rods form a body-centred array, and link by sharing elements of their coordination polyhedra.

Crystal structure of KBSi3O8 isostructural with danburite

1993 ◽  
Vol 57 (386) ◽  
pp. 157-164 ◽  
Author(s):  
Mitsuyoshi Kimata
Keyword(s):  
Crystal Structure ◽  
Direct Method ◽  
Crystal Chemical ◽  
Chemical Formula ◽  
Crystal Chemical Formula ◽  
3 Dimensional ◽  
Tetrahedral Sites ◽  
Structural Types ◽  
Coupled Substitution ◽  
Insight Into

AbstractThe crystal structure of KBSi3O8 (orthorhombic, Pnam, with a = 8.683(1), b = 9.253(1), c = 8.272(1) Å,, V = 664.4(1) Å3, Z = 4) has been determined by the direct method applied to 3- dimensional rcflection data. The structure of a microcrystal with the dimensions 20 × 29 × 37 μm was refined to an unweightcd residual of R = 0.031 using 386 non-zero structure amplitudes. KBSi3O8 adopts a structure essentially different from recdmergneritc NaBSi3O8, with the low albite (NaAlSi3O8) structure, and isotypic with danburite CaB2Si2Os which has the same topology as paracelsian BaAl2Si2O8. The chenfical relationship between this sample and danburitc gives insight into a new coupled substitution; K+ + Si4+ = Ca2+ + B3+ in the extraframework and tetrahedral sites. The present occupancy refinement revealed partial disordering of B and Si atoms which jointly reside in two kinds of general equivalent points, T(1) and T(2) sites. Thus the expanded crystal-chemical formula can be written in the form K(B0.44Si0.56)2(B0.06Si0.94)2O8The systematic trend among crystalline compounds with the M+T3+T4+3O8 formula suggests that they exist in one of four structural types; the feldspar structures with T3+/T4+ ordered and/or disordered forms, and the paracelsian and the hollandite structures.

ChemInform Abstract: Crystal Structure of Pb2SbS2I3, and Re-Examination of the Crystal Chemistry within the Group of (Pb/Sn/Sb) Chalcogeno-Iodides.

ChemInform ◽  
2008 ◽  
Vol 39 (1) ◽  
Author(s):  
Charlotte Doussier ◽  
Yves Moelo ◽  
Philippe Leone ◽  
Alain Meerschaut ◽  
Michel Evain
Keyword(s):  
Crystal Structure ◽  
Crystal Chemistry

Crystal structure determination of the conformation of two bicyclo[3.3.1]nonan-ones

1985 ◽  
Vol 63 (6) ◽  
pp. 1166-1169 ◽  
Author(s):  
John F. Richardson ◽  
Ted S. Sorensen
Keyword(s):  
Crystal Structure ◽  
Direct Methods ◽  
Chair Conformation ◽  
Molecular Structures ◽  
Boat Conformation ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
Final Agreement

The molecular structures of exo-7-methylbicyclo[3.3.1]nonan-3-one, 3, and the endo-7-methyl isomer, 4, have been determined using X-ray-diffraction techniques. Compound 3 crystallizes in the space group [Formula: see text] with a = 15.115(1), c = 7.677(2) Å, and Z = 8 while 4 crystallizes in the space group P21 with a = 6.446(1), b = 7.831(1), c = 8.414(2) Å, β = 94.42(2)°, and Z = 2. The structures were solved by direct methods and refined to final agreement factors of R = 0.041 and R = 0.034 for 3 and 4 respectively. Compound 3 exists in a chair–chair conformation and there is no significant flattening of the chair rings. However, in 4, the non-ketone ring is forced into a boat conformation. These results are significant in interpreting what conformations may be present in the related sp2-hybridized carbocations.

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