Preparation and Structure of Zinc(II) Complexes of Purine and 7-Azaindole

1982 ◽  
Vol 37 (5) ◽  
pp. 653-656 ◽  
Author(s):  
William S. Sheldrick
Keyword(s):  
Acid Solution ◽  
Aqueous Solutions ◽  
Bond Length ◽  
Significant Contribution ◽  
Positive Charge ◽  
Length Distribution ◽  
X Ray ◽  
Bond Length Distribution

Trichloro(purinium)zinc(II) (1) and dichloro-bis-(7-azaindole)zinc(II) (2) have been prepared from respectively 1:1 (in acid solution) and 2:1 aqueous solutions of the parent base and zinc(II) chloride. In the latter case the salt di-[7-azaindolium]zinc(II) tetrachloride (3) is isolated under acid conditions. The structures of 1-3 have been established by X-ray structural analyses. Zinc coordinates the purine nitrogen N(7) in 1 and N(3) of 7-azaindole in 2. N(l) is protonated in 1. The bond length distribution of the cations 3 suggests a significant contribution from a resonance form in which N(9) carries the positive charge

On the effect of Ga and In substitutions in the Ca11Bi10and Yb11Bi10bismuthides crystallizing in the tetragonal Ho11Ge10structure type

2018 ◽  
Vol 74 (3) ◽  
pp. 269-273 ◽  
Author(s):  
Alexander Ovchinnikov ◽  
Svilen Bobev
Keyword(s):  
Bond Length ◽  
Length Distribution ◽  
Structural Response ◽  
Structure Type ◽  
First Principle ◽  
X Ray Diffraction ◽  
Interatomic Distances ◽  
X Ray ◽  
Type Bond ◽  
Bond Length Distribution

The Ga- and In-substituted bismuthides Ca11GaxBi10–x, Ca11InxBi10–x, Yb11GaxBi10–x, and Yb11InxBi10–x(x< 2) can be readily synthesized employing molten Ga or In metals as fluxes. They crystallize in the tetragonal space groupI4/mmmand adopt the Ho11Ge10structure type (Pearson codetI84; Wyckoff sequencen2m j h2e2d). The structural response to the substitution of Bi with smaller and electron-poorer In or Ga has been studied by single-crystal X-ray diffraction methods for the case of Ca11InxBi10–x[x= 1.73 (2); octabismuth undecacalcium diindium]. The refinements show that the In atoms substitute Bi only at the 8hsite. The refined interatomic distances show an unconventional – for this structure type – bond-length distribution within the anionic sublattice. The latter can be viewed as consisting of isolated Bi3−anions and [In4Bi820−] clusters for the idealized Ca11In2Bi8model. Formal electron counting and first-principle calculations show that the peculiar bonding in this compound drives the system toward an electron-precise state, thereby stabilizing the observed bond-length pattern.

scholarly journals Redetermination of β-Ba(PO3)2

2014 ◽  
Vol 70 (2) ◽  
pp. i7-i7 ◽  
Author(s):  
Matthias Weil
Keyword(s):  
Bond Length ◽  
Coordination Polyhedron ◽  
Structure Determination ◽  
Length Distribution ◽  
Anisotropic Displacement Parameters ◽  
The Absolute ◽  
Bond Length Distribution ◽  
Absolute Structure ◽  
Atomic Coordinates

In comparison with the previous structure determination of the β-modification of bariumcatena-polyphosphate that was based on Weissenberg film data [Grenieret al.(1967).Bull. Soc. Fr. Minéral. Cristallogr.90, 24–31], the current CCD-data-based redetermination reveals all atoms with anisotropic displacement parameters, standard uncertainties for the atomic coordinates, and the determination of the absolute structure. Moreover, a much higher accuracy in terms of the bond-length distribution for the polyphosphate chain, with two shorter and two longer P—O distances, was achieved. The structure consists of polyphosphate chains extending parallel to [100] with a periodicity of two PO4tetrahedra. The Ba2+cations are located between the chains and are surrounded by ten O atoms in the form of a distorted coordination polyhedron, with Ba—O distances ranging from 2.765 (3) to 3.143 (3) Å, also reflecting the higher precision of the current redetermination.

Synthesis and Crystal Structures of New 1,3-Disubstituted Imidazoline-2-thiones

2013 ◽  
Vol 68 (11) ◽  
pp. 1239-1252 ◽  
Author(s):  
Gerhard Laus ◽  
Volker Kahlenberg ◽  
Klaus Wurst ◽  
Thomas Müller ◽  
Holger Kopacka ◽  
...  
Keyword(s):  
Bond Length ◽  
Crystal Structures ◽  
1H Nmr ◽  
Significant Contribution ◽  
Resonance Structure ◽  
X Ray Diffraction ◽  
Reference Compound ◽  
X Ray ◽  
Hydrolysis Of ◽  
By Products

Two methods (MeOH/K2CO3, pyridine/Et3N) were assessed for the introduction of sulfur into the 2-position of 1,3-disubstituted quaternary imidazolium salts 1-9 (Cl, I, BF4, PF6, CH3OSO3 were used as anions) to yield nine 1,3-disubstituted imidazoline-2-thiones 10-18 (1, 10: R1 = CH3, R2 = CH3; 2, 11: R1 = OCH2Ph, R2 = CH3; 3, 12: R1 = OCH3, R2 = CH3; 4, 13: R1 = OCH3, R2 = OCH3; 5, 14: R1 = NH2, R2 = CH2Ph; 6, 15: R1 = NCHPh, R2 = CH3; 7, 16: R1 = NH2, R2 = CH3; 8, 17: R1 = NCHPh, R2 = NCHPh; 9, 18: R1 = NH2, R2 = OCH3). Compounds 11-18 represent N-alkyloxy and N-amino imidazoline-2-thiones, whereas 10 served as reference compound. The first method was advantageous for the conversion 1 → 10 due to faster reaction, whereas in the reaction 2 → 11 considerable amounts of by-products were formed. Pure thiones 11, 14, 16, 17, and 18 were obtained only by the second method. Both methods worked for the synthesis of the methoxy derivatives 12 and 13 from 3 and 4, and the benzylideneamino derivative 15 from 6. 1-Amino-3- methylimidazoline-2-thione (16) was also prepared by hydrolysis of the benzylideneamino derivative 15. Crystal structures of seven 1,3-disubstituted imidazoline-2-thiones were determined by singlecrystal X-ray diffraction. Intermolecular C-H···S contacts were identified and, additionally, N-H···S interactions in aminothiones 14 and 16. The 1H NMR shifts of 10 and 13 were satisfactorily correlated with the Kamlet-Abboud-Taft π* and b parameters in ten solvents. From the lack of correlation with the a parameter and from the C=S bond length (average 1.68 Å ) a significant contribution of a mesoionic imidazolium-2-thiolate resonance structure seems unlikely.

Structure and bond length distribution in Hf2Fe and Hf2Co intermetallic compounds

1998 ◽  
Vol 84 (9) ◽  
pp. 4842-4846 ◽  
Author(s):  
B. Cekić ◽  
N. Ivanović ◽  
Z. Rakočević ◽  
V. Koteski ◽  
M. Manasijević ◽  
...  
Keyword(s):  
Bond Length ◽  
Intermetallic Compounds ◽  
Length Distribution ◽  
Bond Length Distribution

scholarly journals Crystal structure oftrans-1,4-bis[(trimethylsilyl)oxy]cyclohexa-2,5-diene-1,4-dicarbonitrile

2014 ◽  
Vol 70 (8) ◽  
pp. 77-79 ◽  
Author(s):  
Florian Glöcklhofer ◽  
Johannes Fröhlich ◽  
Berthold Stöger ◽  
Matthias Weil
Keyword(s):  
Crystal Structure ◽  
Bond Length ◽  
Title Compound ◽  
Length Distribution ◽  
Inversion Symmetry ◽  
Asymmetric Unit ◽  
Compound C ◽  
Tetrahedral Angle ◽  
Bond Length Distribution ◽  
Single Bonds

The asymmetric unit of the title compound, C14H22N2O2Si2, contains one half of the molecule, which is completed by inversion symmetry. The cyclohexa-2,5-diene ring is exactly planar and reflects the bond-length distribution of a pair of located double bonds [1.3224 (14) Å] and two pairs of single bonds [1.5121 (13) and 1.5073 (14) Å]. The tetrahedral angle between thesp3-C atom and the two neighbouringsp2-C atoms in the cyclohexa-2,5-diene ring is enlarged by about 3°.

Effect of Nd content on the energetics of H2O adsorption and defect structure in the Ce(1−x)NdxO(2−0.5x) system

2020 ◽  
Vol 8 (41) ◽  
pp. 21842-21851
Author(s):  
Y. Mordekovitz ◽  
S. Sagi ◽  
S. Barzilai ◽  
S. Hayun
Keyword(s):  
Bond Length ◽  
Defect Structure ◽  
Length Distribution ◽  
Excess Adsorption ◽  
Adsorption Enthalpy ◽  
System P ◽  
Bond Length Distribution

The effect of Nd on the bond length distribution and excess adsorption enthalpy of H2O (relative to pure CeO2) in the Ce(1−x)NdxO(2−0.5x) system.

On measuring the size of distortions in coordination polyhedra

2006 ◽  
Vol 62 (4) ◽  
pp. 692-694 ◽  
Author(s):  
I. David Brown
Keyword(s):  
Bond Length ◽  
Coordination Polyhedron ◽  
Length Distribution ◽  
Higher Moments ◽  
Coordination Polyhedra ◽  
The Third ◽  
Suitable Index ◽  
Average Bond ◽  
Bond Length Distribution ◽  
Unique Index

There is no unique index that measures the size of the distortion found in a coordination polyhedron because different indices can result in a different ordering depending on the mode of the distortion (i.e. the third and higher moments of the bond-length distribution). This paper proposes the increase in the average bond length as a suitable index as this is directly related to the increase in volume of the coordination polyhedron and hence of the unit cell. Some examples are discussed.

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