Über einige Beziehungen zwischhen Kristallstrukturen

1956 ◽  
Vol 11 (11) ◽  
pp. 920-934b
Author(s):  
Konrad Schubert
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Spatial Correlation ◽  
Chemical Elements ◽  
Electron Gas ◽  
Lattice Constants ◽  
Hexagonal Close Packed ◽  
Binary Compounds ◽  
Atomic Radii ◽  
Insight Into

In determining structures we use physical propositions in order to find a likely crystal structure. The same propositions are of value for the ordering of known structures into a natural system. The atomic radii form such a proposition. Another proposition is contained in the spatial correlation of electrons in the electron gas. The question is, whether this correlation is of influence on the crystal structure or not. To gain a first insight into this question, it is useful to know whether the crystal structures are physically compatible with a certain spatial correlation of electrons. Some qualitative rules are given to assess the physical possibility of a spatial correlation of electrons in a crystal structure. For the crystal structures of some chemical elements proposals for electron correlation are given. These proposals account for rationalities existing between some lattice constants, e. g. the axial ratios of the hexagonal close packed structures of Co and Zn. The proposals are also applicable to some binary compounds. With regard to these commensurabilities, it seems possible that the examination of the spatial correlation of electrons may lead to a better understanding of the crystal-chemical empiry.

Structural Studies on N-(2,4,6-Trimethylphenyl)-methyl/ chloro-acetamides, 2,4,6-(CH3)3C6H2NH-CO-CH3–yXy (X = CH3 or Cl and y = 0, 1, 2)

2006 ◽  
Vol 61 (10-11) ◽  
pp. 588-594 ◽  
Author(s):  
Basavalinganadoddy Thimme Gowda ◽  
Jozef Kožíšek ◽  
Hartmut Fuess
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Structural Data ◽  
The Other ◽  
Side Chain ◽  
Structural Studies ◽  
Asymmetric Unit ◽  
Lattice Constants ◽  
Peptide Linkage ◽  
The Mean

TMPAThe effect of substitutions in the ring and in the side chain on the crystal structure of N- (2,4,6-trimethylphenyl)-methyl/chloro-acetamides of the configuration 2,4,6-(CH3)3C6H2NH-COCH3− yXy (X = CH3 or Cl and y = 0,1, 2) has been studied by determining the crystal structures of N-(2,4,6-trimethylphenyl)-acetamide, 2,4,6-(CH3)3C6H2NH-CO-CH3 (); N-(2,4,6- trimethylphenyl)-2-methylacetamide, 2,4,6-(CH3)3C6H2NH-CO-CH2-CH3 (TMPMA); N-(2,4,6- trimethylphenyl)-2,2-dimethylacetamide, 2,4,6-(CH3)3C6H2NH-CO-CH(CH3)2 (TMPDMA) and N-(2,4,6-trimethylphenyl)-2,2-dichloroacetamide, 2,4,6-(CH3)3C6H2NH-CO-CHCl2 (TMPDCA). The crystallographic system, space group, formula units and lattice constants in Å are: TMPA: monoclinic, Pn, Z = 2, a = 8.142(3), b = 8.469(3), c = 8.223(3), β = 113.61(2)◦; TMPMA: monoclinic, P21/n, Z = 8, a = 9.103(1), b = 15.812(2), c = 16.4787(19), α = 89.974(10)◦, β = 96.951(10)◦, γ =89.967(10)◦; TMPDMA: monoclinic, P21/c, Z = 4, a =4.757(1), b= 24.644(4), c =10.785(2), β = 99.647(17)◦; TMPDCA: triclinic, P¯1, Z = 2, a = 4.652(1), b = 11.006(1), c = 12.369(1), α = 82.521(7)◦, β = 83.09(1)◦, γ = 79.84(1)◦. The results are analyzed along with the structural data of N-phenylacetamide, C6H5NH-CO-CH3; N-(2,4,6-trimethylphenyl)-2-chloroacetamide, 2,4,6-(CH3)3C6H2NH-CO-CH2Cl; N-(2,4,6-trichlorophenyl)-acetamide, 2,4,6-Cl3C6H2NH-COCH3; N-(2,4,6-trichlorophenyl)-2-chloroacetamide, 2,4,6-Cl3C6H2NH-CO-CH2Cl; N-(2,4,6-trichlorophenyl)- 2,2-dichloroacetamide, 2,4,6-Cl3C6H2NH-CO-CHCl2 and N-(2,4,6-trichlorophenyl)- 2,2,2-trichloroacetamide, 2,4,6-Cl3C6H2NH-CO-CCl3. TMPA, TMPMA and TMPDCA have one molecule each in their asymmetric units, while TMPDMA has two molecules in its asymmetric unit. Changes in the mean ring distances are smaller on substitution as the effect has to be transmitted through the peptide linkage. The comparison of the other bond parameters reveal that there are significant changes in them on substitution.

scholarly journals Darstellung und Kristallstruktur von K2Sn2S5 und K2Sn2Se5 / Preparation and Crystal Structure of K2Sn2S5 and K2Sn2Se5

1992 ◽  
Vol 47 (2) ◽  
pp. 197-200 ◽  
Author(s):  
Kurt O. Klepp
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Structure Type ◽  
Slow Cooling ◽  
Bond Lengths ◽  
Trigonal Bipyramidal ◽  
Equatorial Bond ◽  
Binary Compounds ◽  
R Factors ◽  
Distorted Trigonal Bipyramidal

K2Sn2S5 and K2Sn2Se5 were prepared by reacting stoichiometric powdered mixtures of the binary compounds K2S or K2Se with Sn and the corresponding chalcogen at 1070 K, followed by slow cooling of the melt. The two compounds are isostructural and crystallize with the Tl2Sn2S5 structure type, s.g. C 2/c, Z = 4 with a = 11.072(5) Å, b = 7.806(3)Å, c = 11.517(5)Å, β = 108.43(2)° for K2Sn2S5 and a = 11.613(5)Å, b = 8.189(3) Å, c = 11,897(6) Å, β = 108.28(2)° for K2Sn2Se5. The crystal structures were refined to conventional R-factors of 0.032 and 0.031, respectively. Sn-atoms are in a distorted trigonal-bipyramidal chalcogen coordination. The average equatorial bond lengths are Sn -S: 2.427 Å and Sn -Se: 2.552 Å , the axial ones are Sn -S: 2.600 Å and Sn -Se: 2.774 Å.

Ternäre Varianten des Pyrit-Typs: Darstellung und Struktur von SrPt4P6, SrPt4As6, BaPt4As6 und BaPt2P3 / Ternary Pyrite-Type Derivatives: Preparation and Crystal Structure of SrPt4P6, SrPt4As6, BaPt4As6 and BaPt2P3

1987 ◽  
Vol 42 (4) ◽  
pp. 507-513 ◽  
Author(s):  
Guido Wenski ◽  
Albrecht Mewis
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Related Structure ◽  
Formula Unit ◽  
Lattice Constants

Abstract The isotypic compounds SrPt4P6 , SrPt4As6 and BaPt4As6 were found to crystallize with a Pyrite-type derivative structure (monoclinic, C2/c, Z = 4) in which one Sr or Ba atom per formula unit occupies the position of a P2 or As2 pair. BaPt2P3 forms another Pyrite-type related structure (monoclinic, P21/c, Z = 4) built up by Ba2Pt and Pt3P6 layers. All crystal structures were refined from four-circle diffractometer data, the lattice constants are:SrPt4P6: a = 825.2(1) pm, b = 798.4(1) pm, c = 1142.8(1) pm, β = 90.74(2)°; SrPt4As6: a = 858.2(1) pm, b = 832.1(1) pm, c = 1194.5(1) pm, β = 91.00(2)°; BaPt4As6: a = 868.8(1) pm, b = 833.3(1) pm, c = 1197.1(1) pm, β = 90.81(2)°; BaPt2P3 a = 835.2(1) pm, b = 577.6(1) pm, c = 1157.4(1) pm, β = 106.73(2)°.

New insight into the crystal structure of orthorhombic edingtonite: evidence for a split Ba site

2004 ◽  
Vol 68 (1) ◽  
pp. 167-175 ◽  
Author(s):  
G. D. Gatta ◽  
T. Boffa Ballaran
Keyword(s):  
Crystal Structure ◽  
British Columbia ◽  
Crystal Structures ◽  
Lattice Parameters ◽  
Space Group ◽  
Physicochemical Conditions ◽  
Report Data ◽  
First Time ◽  
Insight Into

AbstractOrthorhombic edingtonite has been found coexisting with tetragonal edingtonite in a specimen from Ice River, British Columbia, Canada.We report data on the composition and crystal structure of the orthorhombic sample. Lattice parameters are: a = 9.5341(6), b = 9.6446(6), c = 6.5108(7)Å, V = 598.68(8)Å 3. The crystal structure was refined in space group P 21212 to R1 = 1.8% using 879 observed reflections. For the first time, evidence for splitting of the extra-framework Ba site in two different sites (Ba1, Ba2), ~0.37 Å apart, is demonstrated. A comparison with the published crystal structures of tetragonal and orthorhombic edingtonite is made.The present result supports the suggestion that the two edingtonite phases are a consequence of different nucleation phenomena and not different physicochemical conditions.

Crystal Structure Studies on Arylsulphonamides and N-Chloro-Arylsulphonamides

2007 ◽  
Vol 62 (7-8) ◽  
pp. 417-424
Author(s):  
Basavalinganadoddy Thimme Gowda ◽  
Sabine Foro ◽  
Jozef Kožíšek ◽  
Hartmut Fuess ◽  
Keyword(s):  
Crystal Structure ◽  
Double Bond ◽  
Hydrogen Bonds ◽  
Crystal Structures ◽  
Sodium Salt ◽  
Molecular Geometry ◽  
Asymmetric Unit ◽  
Sodium Salts ◽  
Lattice Constants ◽  
Oxygen Atoms

The effect of ring substitution and N-chlorination on the molecular geometry of arylsulphonamides and N-chloro-arylsulphonamides have been studied by determining the crystal structures of 2-methyl- 4-chloro-benzenesulphonamide (2M4CBSA) and the sodium salt of N-chloro-2-methyl-4-chlorobenzenesulphonamide (NaNC2M4CBSA). The results are analyzed along with the crystal structures of benzenesulphonamide, 4-methyl-benzenesulphonamide and 4-chloro-benzenesulphonamide. The crystal structure of NaNC2M4CBSA has also been compared and correlated with the crystal structures of the above compounds and those of the sodium salts of N-chloro-benzenesulphonamide, Nchloro- 4-methyl-benzenesulphonamide, N-chloro-4-chloro-benzenesulphonamide and N-chloro-2,4- dichloro-benzenesulphonamide. The crystal system, space group, formula units and lattice constants in Å of the new structures are: 2M4CBSA: triclinic, P1, Z = 4, a = 7.9030(10), b = 8.6890(10), c = 13.272(2), α = 100.680(10)°, β = 98.500(10)°, γ = 90.050(10)°; NaNC2M4CBSA: monoclinic, C2/c, Z =4, a = 10.9690(10), b = 6.7384(6), c = 30.438(2), β = 98.442(7)°. The structure of 2M4CBSA is quite complex with four molecules in its asymmetric unit. The S-N bond length slightly decreases with substitution of electron-withdrawing groups, while the effect is more pronounced with disubstitution. The structure of NaNC2M4CBSA confirms that there is no interaction between nitrogen and sodium, and Na+ is attached to one of the sulphonyl oxygen atoms. The Na+ coordination sphere involves oxygen atoms from water moleculess of crystallization and neighbouring molecules. The S-N distance of 1.586 Å for the compound is consistent with a S-N double bond. The molecules are held together by hydrogen bonds with distances varying from 2.12 to 2.85 Å.

Über die Kristallstrukturen der Tellurate Pb3Fe2Te2O12 und Pb2CoTeO6 / On the Crystal Structures of the Tellurates Pb3Fe2Te2O12 and Pb2CoTeO6

1997 ◽  
Vol 52 (1) ◽  
pp. 35-39 ◽  
Author(s):  
B. Wedel ◽  
Hk. Müller-Buschbaum
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Crystal Structures ◽  
Negative Charge ◽  
X Ray ◽  
Space Groups ◽  
Lattice Constants ◽  
Coulomb Term ◽  
Lone Pairs ◽  
Symmetry Space

Pb3Fe2Te2O12 (I) and Pb2CoTeO6 (II) have been prepared by crystallization from melts. Single crystal X-ray investigations led to monoclinic (I) and tetragonal (II) symmetry, space groups C4s-Cc and D174h-14/mmm. Lattice constants I: a = 9.866(3), b = 15.332(4), c = 7.172(2) Å, β = 111.34(3)°, Z = 4. II: a = 5.661(5), c = 8.004(7) Å, Z = 2. (I) represents a new crystal structure, characterized by a network of octahedra occupied by Fe3+ and Te6+ in a disordered manner. The centres of negative charge of the lone pairs of Pb2+ in I are estimated by Coulomb term calculations. II belongs to the elpasolithe type

scholarly journals Distinct effects of Q925 mutation on intracellular and extracellular Na+ and K+ binding to the Na+, K+-ATPase

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Hang N. Nielsen ◽  
Kerri Spontarelli ◽  
Rikke Holm ◽  
Jens Peter Andersen ◽  
Anja P. Einholm ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Binding Sites ◽  
Functional Role ◽  
Transmembrane Helix ◽  
Binding Properties ◽  
Ion Translocation ◽  
Extracellular Side ◽  
Insight Into

Abstract Three Na+ sites are defined in the Na+-bound crystal structure of Na+, K+-ATPase. Sites I and II overlap with two K+ sites in the K+-bound structure, whereas site III is unique and Na+ specific. A glutamine in transmembrane helix M8 (Q925) appears from the crystal structures to coordinate Na+ at site III, but does not contribute to K+ coordination at sites I and II. Here we address the functional role of Q925 in the various conformational states of Na+, K+-ATPase by examining the mutants Q925A/G/E/N/L/I/Y. We characterized these mutants both enzymatically and electrophysiologically, thereby revealing their Na+ and K+ binding properties. Remarkably, Q925 substitutions had minor effects on Na+ binding from the intracellular side of the membrane – in fact, mutations Q925A and Q925G increased the apparent Na+ affinity – but caused dramatic reductions of the binding of K+ as well as Na+ from the extracellular side of the membrane. These results provide insight into the changes taking place in the Na+-binding sites, when they are transformed from intracellular- to extracellular-facing orientation in relation to the ion translocation process, and demonstrate the interaction between sites III and I and a possible gating function of Q925 in the release of Na+ at the extracellular side.

scholarly journals Crystal structure of human CRMP-4: correction of intensities for lattice-translocation disorder

2014 ◽  
Vol 70 (6) ◽  
pp. 1680-1694 ◽  
Author(s):  
Rajesh Ponnusamy ◽  
Andrey A. Lebedev ◽  
Steffen Pahlow ◽  
Bernhard Lohkamp
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Nerve Cell ◽  
Neuronal Cell ◽  
Correlation Coefficients ◽  
Cell Development ◽  
Structural Comparison ◽  
Gene Encoding ◽  
Novel Method ◽  
Insight Into

Collapsin response mediator proteins (CRMPs) are cytosolic phosphoproteins that are mainly involved in neuronal cell development. In humans, the CRMP family comprises five members. Here, crystal structures of human CRMP-4 in a truncated and a full-length version are presented. The latter was determined from two types of crystals, which were either twinned or partially disordered. The crystal disorder was coupled with translational NCS in ordered domains and manifested itself with a rather sophisticated modulation of intensities. The data were demodulated using either the two-lattice treatment of lattice-translocation effects or a novel method in which demodulation was achieved by independent scaling of several groups of intensities. This iterative protocol does not rely on any particular parameterization of the modulation coefficients, but uses the current refined structure as a reference. The best results in terms ofRfactors and map correlation coefficients were obtained using this new method. The determined structures of CRMP-4 are similar to those of other CRMPs. Structural comparison allowed the confirmation of known residues, as well as the identification of new residues, that are important for the homo- and hetero-oligomerization of these proteins, which are critical to nerve-cell development. The structures provide further insight into the effects of medically relevant mutations of theDPYSL-3gene encoding CRMP-4 and the putative enzymatic activities of CRMPs.

Alkalimetall-Oxosilicate A6[Si3O9] und A6[Si2O7] (A = Rb, Cs): Darstellung und Kristallstruktur/ The Alkaline Metal Oxo-Silicates A6[Si3O9] and A6[Si2O7] (A = Rb, Cs): Preparation and Crystal Structure

2001 ◽  
Vol 56 (4-5) ◽  
pp. 423-430 ◽  
Author(s):  
C. Hoch ◽  
C. Röhr
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Crystal Structures ◽  
Alkali Metals ◽  
Alkaline Metal ◽  
Monoclinic System ◽  
Space Group ◽  
X Ray ◽  
Lattice Constants

Abstract The title compounds were synthesized via reaction of quartz and AO2 (A = Rb, Cs) with the elemental alkali metals. Their crystal structures were determined on the basis of single crystal X-ray data. All compounds crystallize in the monoclinic system with space group P21/c and lattice constants a = 656.0(l)/684.7(3), b = 1329.7(3)/1375.7(4), c = 1647.6(3)/1703.6(8) pm, β = 107.78(3)/108.23(2)°, Z = 4 (A6[Si3O9], A = Rb/Cs) and a = 668.59(8)/711.4(1), b = 911.37(9)/952.1(2), c = 1121.09(9)/1192.7(7) pm, β = 125.52(9)/126.22(3)°, Z = 2(A6[Si2O7], A = Rb/Cs) respectively. The rubidium and cesium compounds are isotypic with the corresponding potassium silicates.

A new method of calculating interatomic spacing: the equal-ratio method

2019 ◽  
Vol 52 (2) ◽  
pp. 289-295
Author(s):  
Quncheng Fan
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Common Factor ◽  
New Method ◽  
Ratio Method ◽  
Analytical Geometry ◽  
Interatomic Spacing ◽  
Hexagonal Close Packed ◽  
The Common

Based on a simple principle of analytical geometry, a new equal-ratio method has been developed to calculate the interatomic spacing of crystal structures. If an atom (x 2, y 2, z 2) or its equi-position atom (e + x 2, f + y 2, g + z 2) (e, f and g are integers) is located at the 1/r ≤ 1 of one interatomic spacing period d′[uvw] on the [uvw] atomic row passing through the atom (x 1, y 1, z 1), the distance between the two atoms can be calculated by the formula d [uvw] (1/r) = d′[uvw]/r, where d′[uvw] = (u 2 a 2 + v 2 b 2 + w 2 c 2 + 2uvabcosγ + 2vwbccosα + 2uwaccosβ)1/2 is the interlattice point spacing of the corresponding primary lattice of the crystal structure, 1/r is the interatomic spacing coefficient, and r is equal to the reciprocal of the common factor of (x 2 − x 1), (y 2 − y 1) and (z 2 − z 1). The reliability and advantages (no auxiliary view is required, suitable for arbitrary directions and for all crystal structures) of the equal-ratio method have been examined by calculations for the β-cristobalite SiO2 structure and Cu3Au I superstructure as well as face-centred cubic, body-centred cubic and hexagonal close-packed structures.

Sign in / Sign up

Export Citation Format

Share Document