Pentacoordination and ionic character: crystal structure of Ph4SbBr

1989 ◽  
Vol 67 (1) ◽  
pp. 63-70 ◽  
Author(s):  
Osvald Knop ◽  
Beverly R. Vincent ◽  
T. Stanley Cameron
Keyword(s):  
Crystal Structure ◽  
Axial Position ◽  
Ionic Character ◽  
High Symmetry ◽  
Trans Effect ◽  
Bond Lengths ◽  
Axial Bond ◽  
The Mean ◽  
High Degree ◽  
Very High

Ph4SbBr (P21/n, a = 12.282(2) Å, b = 10.656(1) Å, c = 16.156(1) Å, β = 104.92(7)°, Z = 4) crystallizes with the same space group as Ph4SbCl, but the two compounds are not isostructural. The structure of Ph4SbBr consists of layers of Ph4SbBr molecules with the Br atoms almost exactly in the [Formula: see text] planes. The coordination figure of the Sb atom is a trigonal bipyramid (TBP) with Br in an axial position. The Sb—Br distance, 2.950(1) Å is the longest reported for Sb(V) to date. The Sb(V)—Hal bond lengths and the Ph4SbBr and Ph4SbCl structures are compared in detail. Analysis of a large sample of Ph4EX (E = P, As) structures and of all the available R4EX (E = Sb, Bi; R = Ph, Me) structures shows that the former are always ionic, R4E+X−, whereas in the latter the observed coordination figures represent R4EX trigonal bipyramids with various degrees of axial distortion. The inverse variation of the axial bond lengths (the trans effect) in the TBP Sb compounds can be quantified as Sb—Cax ~ 2.4(Sb—X)−1/9 to a very high degree of correlation. This and other geometric relationships show that there exists a limiting E—X bond length (~3.3 Å for E = Sb and ~3.5 Å for E = Bi when X is oxygen) at which the TBP coordination becomes unstable and changes over to a tetrahedral R4E. This change is accompanied by a rearrangement of the structure to an ionic R4E+X− solid (of high symmetry where permitted by the size and shape of the anion) with [Formula: see text] separations no smaller than ~4 Å when E = Sb or Bi and X = O. The distribution of the CEC angles in the Ph4EX (E = P, As) sample is analyzed; the mean (uncorrected) P—C and As—C bond lengths in Ph4E+ are found to be 1.789(11) and 1.902(12) Å, respectively. Keywords: crystal structure, organoantimony compounds, Ph4SbBr, pentacoordination, tetraphenylantimony bromide.

Dependence of the Distortion of the Square Pyramids in N, N-Dimethylethylenediammonium Pentachloroantimonate(III) on the Geometry of Hydrogen Bonds

2001 ◽  
Vol 56 (6) ◽  
pp. 521-525 ◽  
Author(s):  
Maciej Bujak ◽  
Jacek Zaleski
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Intermolecular Interactions ◽  
Mean Value ◽  
The Other ◽  
Monoclinic System ◽  
Bond Lengths ◽  
Pyramidal Geometry ◽  
The Mean ◽  
Square Pyramidal Geometry

AbstractN ,N-Dimethylethylenediammonium pentachloroantimonate(III) crystallizes in the monoclinic system, in space group P21/c (a = 12.460(2), b = 10.252(2), c = 10.330(2) Å, β = 97.75(3)°, V = 1307.5(4) Å3, Z = 4, dc = 1.997, dm = 1.99(2) g/cm3). The crystal structure of [(CH3)2NH(CH2)2NH3][SbCl5] consists of isolated [SbCl5]2- anions and [(CH3)2NH(CH2)2NH3]2+ cations. The [SbCl5]2- anion has a distorted square pyramidal geometry, presenting one short axial and four long equatorial Sb-Cl bonds. The square pyramids are characteristically stacked one close to the other, parallel to the c axis. The voids between the anionic sublattice are filled by [(CH3)2NH(CH2)2NH3]2+ cations. The five non-equivalent Sb-Cl bond distances within the [SbCl5]2- square pyramid are significantly different. The equatorial Sb-Cl bonds are in the range 2.427(2)-2.968(2) Å, whereas the axial one is 2.384(1) Å long. The study reveals that N-H...C1 hydrogen bonds are responsible for the deformation of equatorial Sb-Cl bonds from the mean value of 2.654(7) Å. Analysis of intermolecular interactions between the [SbCl5]2- pyramids in the structure, reflected in changes of Sb-Cl bond lengths from the values characteristic of non-interacting pyramids, leads to the conclusion that the van der Waals radius of Sb is significantly smaller than that estimated by Pauling.

Pentagonal pyramidal lead coordination in the crystal structure of dimeric diaquopyridine-2,6-dicarboxylatolead(II) pyridine-2,6-dicarboxylic acid monohydrate

1979 ◽  
Vol 57 (18) ◽  
pp. 2498-2503 ◽  
Author(s):  
A. Beveridge ◽  
W. Bushnell
Keyword(s):  
Crystal Structure ◽  
Dicarboxylic Acid ◽  
Electron Pair ◽  
Solid Angle ◽  
Lone Pair ◽  
Axial Position ◽  
Asymmetric Unit ◽  
Inversion Point ◽  
The Mean ◽  
Lead Complex

The crystal structure of dimeric diaquopyridine-2,6-dicarboxylatolead(II) pyridine-2,6-dicarboxylic acid monohydrate, empirical formula and asymmetric unit C14H14N2O11Pb, has been solved and refined to R = 0.081, Rw = 0.100. The space group was [Formula: see text] with a = 1073.8(3), b = 1123.2(5), c = 705.0(3) pm, α = 101.28(8)°, β = 95.42(6)°, γ = 92.80(7)°, ρ = 2.37 g cm−3 (meas.). Measurements were done on an automatic 4-circle diffractometer ([Formula: see text], λ = 71.069 pm), and corrected for absorption. The lead complex is dinuclear with an inversion point at the centre of the double bridging. Each lead atom has distorted pentagonal pyramidal coordination with a water molecule at the apex. The basal ligands are water and terdentate pyridine-2,6-dicarboxylate. The double bridging is by one of the coordinated carboxylic oxygen atoms and its inverse. The electron pair geometry is assumed to be pentagonal bipyramidal with a stereochemically active lone pair occupying considerable solid angle in an axial position. Bond lengths (±2 pm) are: Pb—OH2 (apex), 259; Pb—OH2 (basal), 273; Pb—O, 251, 258, 273; Pb—N, 259. The mean of the bond angles at Pb involving the apical oxygen is 77°. The unit cell contains two water and two dicarboxylic acid molecules of crystallisation which are involved in an H-bonding network with one bond for each hydrogen attached to oxygen in the structure.

Preparation and Crystal Structure of Hexapotassium-μ-Oxo-Hexathiodititanate(IV), K6Ti2OS6

2003 ◽  
Vol 58 (1) ◽  
pp. 163-167 ◽  
Author(s):  
Kurt O. Klepp ◽  
Ferdinand Fabian
Keyword(s):  
Crystal Structure ◽  
Oxygen Atom ◽  
Title Compound ◽  
Bond Angle ◽  
Tetrahedral Configuration ◽  
Bond Lengths ◽  
Pale Yellow ◽  
Intimate Mixture ◽  
The Mean ◽  
Complex Anions

Abstract Pale yellow crystals of the title compound were obtained by reacting an intimate mixture of K2S, K2S2O4, Ti and S at 650 °C. K6Ti2OS6 is monoclinic, mP60, s. g. P21/c. It is characterized by the formation of bitetrahedral complex anions, [S3TiOTiS3]6−, which adopt a staggered conformation. The mean Ti-S and Ti-O bond lengths are 2.242(1) and 1.836(2) Å , respectively, the Ti-O-Ti bond angle is 153.8(2)°. Two K+ ions complete the coordination of the bridging oxygen atom by the cations to a heavily distorted tetrahedral configuration. The anions are arranged in corrugated slabs running parallel to (100). The packing and crystallographic relationship to K6Co2O7 are discussed.

Darstellung und Kristallstruktur von Na4GeSe4: Ein neues ortho-Selenogermanat(IV)

1985 ◽  
Vol 40 (7) ◽  
pp. 878-882 ◽  
Author(s):  
Kurt O. Klepp
Keyword(s):  
Crystal Structure ◽  
Orthorhombic Structure ◽  
Tetrahedral Geometry ◽  
Space Group ◽  
Bond Lengths ◽  
Structure Space ◽  
Mixed Cation ◽  
The Mean

Abstract Na4GeSe4 was obtained from a stoichiometric melt of Na2Se, Ge and Se at 750 °C. It crystallizes with a new orthorhombic structure, space group Pnma, with a = 28.518(8), b - 9.447(5), c = 7.128(2) Å , Z = 8. The crystal structure was refined to a conventional R of 0.074 for 1236 reflections with I > 3 σ (I) (diffractometer data). It is characterized by discrete GeSe44--anions with almost regular tetrahedral geometry. Two independent anions appear in the structure, the mean Ge - Se-bond lengths are 2.345 and 2.353 Å, resp. The Na+-ions are coordinated to 4 -6 chalcogen atoms in the range 2.88-3.28 Å. The structure is composed of mixed cation-anion-slabs, 2∞ [Na2(GeSe4)2-], which run parallel to the bc-plane and are separated from each other by corrugated 36-layers of Na+-ions.

The crystal structure of p-diethylaminobenzenediazonium hexafluorophosphate

1985 ◽  
Vol 63 (2) ◽  
pp. 332-335 ◽  
Author(s):  
Richard G. Ball ◽  
Richard MacLeod Elofson
Keyword(s):  
Crystal Structure ◽  
Least Squares ◽  
Triple Bond ◽  
Direct Methods ◽  
Full Matrix ◽  
Space Group ◽  
Bond Lengths ◽  
The Mean ◽  
Least Squares Techniques ◽  
Diazo Group

p-Diethylaminobenzenediazonium hexafluorophosphate, C10H14N3+•PF6−, crystallized in space group [Formula: see text] with a = 12.105(4), b = 12.340(5), c = 10.439(4) Å, α = 96.53(3), β = 104.11(3), γ = 64.44(3)°, and Z = 4. The structure was solved using direct methods and refined with full-matrix least-squares techniques on F, to a final R of 0.054 for 1917 reflections with F2 > 3σ(F2). The mean bond lengths for the diazo group are: N—N 1.096(6); C—N 1.357(7) Å. The geometry of the molecule is discussed in terms of the possible resonance forms and it is shown to be consistent with a form in which the N—N triple bond is essentially intact and the aminobenzene moiety has "quinoidal" character.

The crystal structure of deuterated benzene

1987 ◽  
Vol 414 (1846) ◽  
pp. 47-57 ◽  
Keyword(s):  
Crystal Structure ◽  
Neutron Diffraction ◽  
Molecular Orbital Calculations ◽  
Bond Lengths ◽  
M 10 ◽  
Cell Dimensions ◽  
Experimental Errors ◽  
The Mean ◽  
Unit Cell Dimensions ◽  
Deuterated Benzene

The crystal structure of deuterated benzene has been refined by single-crystal neutron diffraction analysis at 15 and 123 K. The unit-cell dimensions were also measured at 52.6 and 80 K, and the thermalexpansion coefficients at all four temperatures were calculated. The molecules have C 3v symmetry with a small chair-distortion from D 6h , which is possibly significant for the carbon atoms and significant for the deuterium atoms. The mean observed bond lengths at 15 K [123 K] are C-C = 1.3972(5) Å [1.3940(9) Å] (1 Å = 10 -10 m = 10 -1 nm); C-D = 1.0864(7) Å [1.0838(10) Å]. When corrected for molecular libration, the corresponding rest values are 1.3980 Å [1.3985 Å]; 1.088 Å [1.088 Å]. Ab initio molecular orbital calculations at the MP-2/6-31G* level gave energy-optimized bond lengths of 1.395 and 1.087 Å for the isolated molecule at rest, in agreement with the corrected values from the crystal structure within the experimental errors.

Validation of a pedometer algorithm as a tool for evaluation of locomotor behaviour in dairy Mediterranean buffalo

2017 ◽  
Vol 84 (4) ◽  
pp. 391-394 ◽  
Author(s):  
Luigi D'Andrea ◽  
Jacopo Guccione ◽  
Maher Alsaaod ◽  
Ramona Deiss ◽  
Antonio Di Loria ◽  
...  
Keyword(s):  
Video Recording ◽  
Warning System ◽  
Natural Occurrence ◽  
3 Dimensional ◽  
Locomotor Behaviour ◽  
Standing Up ◽  
The Mean ◽  
High Degree ◽  
Very High ◽  
Walking Time

This research communication validates an algorithm to monitor natural occurrence of locomotor behaviours in dairy Mediterranean buffalo based on the output of a 3-dimensional accelerometer (RumiWatch®, pedometer). Several characteristics of the locomotor behaviour were detected with a very high (up-right, lying and standing time) or high degree of correlation (walking time and number of strides) and a low mean difference with the video recording. The proportion of correctly detected events exceeded 99 % for the following variables: stand up and lie down events, as well as number of lying, standing or walking bouts. The mean relative measurement error was less than 10 % for the variables: lying, standing, up-right times and number of strides as compared with gold standard. This new algorithm may represent the base for a future early and real-time disease warning system aiming to gain higher health standard in these ruminants.

The Crystal Structure of KAlP2O7

1973 ◽  
Vol 51 (16) ◽  
pp. 2613-2620 ◽  
Author(s):  
Hok Nam Ng ◽  
Crispin Calvo
Keyword(s):  
Crystal Structure ◽  
Spherical Shell ◽  
Bond Length ◽  
Least Squares ◽  
Least Squares Method ◽  
Full Matrix ◽  
Bond Lengths ◽  
The Mean ◽  
R Value ◽  
Oxygen Atoms

KAlP2O7 crystallizes as monoclinic crystals with a = 7.308(8), b = 9.662(6), c = 8.025(4) Å, β = 106.69(7)°, z = 4 and space group P21/c. The structure was refined from 1394 observed reflections by full-matrix least-squares method to a final R value of 0.032. The P2O74− anion consists of a pair of corner-sharing PO4 groups in a nearly staggered configuration. The mean bridging and terminal P—O bond lengths are 1.607 and 1.509 Å, respectively, and the P—O—P angle is 123.2°. The anions lie in planes parallel to (001). The Al ions are bonded to six oxygen atoms contributed by anions in three layers of P2O7 groups. The average Al—O bond length is 1.889 Å. The potassium ion is coordinated to ten oxygen atoms lying within a spherical shell with inner and outer radii of 2.739 and 3.185 Å.

Crystal structure of β-Cu2P2O7

1968 ◽  
Vol 46 (4) ◽  
pp. 605-612 ◽  
Author(s):  
B. E. Robertson ◽  
C. Calvo
Keyword(s):  
Crystal Structure ◽  
High Temperature ◽  
Low Temperature ◽  
Thermal Parameters ◽  
X Ray ◽  
Bond Lengths ◽  
Disordered Structure ◽  
Anisotropic Motion ◽  
Axial Bond ◽  
Ray Methods

The crystal structure of β-CU2P2O7 has been determined by X-ray methods. The crystals are monoclinic with a = 6.827(8) Å, b = 8.118(10) Å, c = 4.576(6) Å, β = 108.85(10)°, Z = 2, and space group C2/m. This structure is analogous to that of the mineral thortveitite and the high temperature forms of the pyrophosphates of Zn, Mg, and Mn. The cations are octahedrally coordinated to oxygen atoms with equatorial Cu—O bonds of 2.00 Å and 1.94 Å while the axial bond lengths are 2.58 Å. The anion has inner P—O bonds of 1.542 Å and average terminal bonds of 1.509 Å. In addition to the usual refinement with anisotropic thermal parameters, the structure has been refined in terms of a disordered structure generated from the low temperature α form of CU2P2O7. This disordered model agrees as well with the data (R = 0.12) as the structure based on the thortveitite structure with large anisotropic motion assigned to the atoms.

Oxoporphyrins – The Molecular Structure of 5,15-Dioxo-2,3,7,8,12,13,17,18-octaethyl-porphodimethene-thallium(III) Chloride

1992 ◽  
Vol 47 (6) ◽  
pp. 837-841 ◽  
Author(s):  
Mathias O. Senge ◽  
Kevin M. Smith
Keyword(s):  
Molecular Structure ◽  
Crystal Structure ◽  
Title Compound ◽  
Structural Information ◽  
Axial Position ◽  
Carbonyl Groups ◽  
The Mean

The crystal structure of the title compound was determined in order to obtain structural information on a tetrapyrrole bearing meso-oxo-functions. C36H42N4O2T1C1 · CH3OH, P1̄, a = 10.358(2), b = 12.344(3), c = 15.490(3) Å, a = 84.36(2)°, β = 78.53(2)°, γ = 82.26(2)°, V = 1918.2(7) Å3, Z = 2, 130 K, R = 0.04 for 6749 reflections with I > 4σ(Ι). The structure consists of the penta-coordinated thallium ligated by the four nitrogens of the porphodimethene ligand and a chloride in the axial position. The central macrocycle shows some degree of ruffling with the carbonyl groups pointing slightly above and below the mean plane of the molecule.

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