Synthesis, structure and DFT calculations of 1,2-N-substituted o-carboranes

2019 ◽  
Vol 48 (21) ◽  
pp. 7242-7248
Author(s):  
Ronglin Pang ◽  
Junxia Li ◽  
Zhongzheng Cui ◽  
Cheng Zheng ◽  
Zhifang Li ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Bond Lengths ◽  
Secondary Amino ◽  
The Relationship ◽  
Electron Effects

A series of 1,2-N-substituted o-carboranes were obtained. Ultra-long C–C distances were found in the secondary-amino o-carboranes 3. The relationship between C–C bond lengths and the electron effects of the benzyl groups was discussed.

La- and Lu-agardite – preparation, crystal structure, vibrational and magnetic properties

2020 ◽  
Vol 75 (1-2) ◽  
pp. 191-199
Author(s):  
Aleksandr M. Golubev ◽  
Eva Brücher ◽  
Armin Schulz ◽  
Reinhard K. Kremer ◽  
Robert Glaum
Keyword(s):  
Crystal Structure ◽  
Magnetic Properties ◽  
Dft Calculations ◽  
Powder Diffraction ◽  
Hexagonal Structure ◽  
Water Molecules ◽  
X Ray ◽  
Bond Lengths ◽  
Inner Diameter ◽  
Low Dimensional

AbstractPolycrystalline samples of La- and Lu-agardite with the composition RECu6(OH)6(AsO4)3 · n H2O (RE = La, Lu; n≈3) have been prepared and the structure of the products was determined by X-ray powder diffraction studies. The characterization has been complemented by Raman and UV/Vis spectroscopic, magnetic and TGA investigations. DFT calculations support the conclusions drawn from the experiments. The arsenates RECu6(OH)6(AsO4)3 · n H2O (RE = La, Lu; n≈3) are isostructural with the mineral mixite and crystallize with a hexagonal structure which contains ribbons of edge-sharing [CuO5] square-pyramids extending along the hexagonal axis. They are interconnected via (AsO4)3− groups to form hexagonal tubes of about 10 Å inner diameter. Such zeolite-like tubes host water molecules, which can be reversibly removed at moderate temperatures (T≈100°C). Like in mixite and YCu6(OH)6(AsO4)3 · 3 H2O, the Cu2+ cations in RECu6(OH)6(AsO4)3 · n H2O (RE = La, Lu; n≈3) exhibit low-dimensional antiferromagnetic properties, which are subject to changes in the Cu–O–Cu bond lengths and angles due to the lanthanide contraction.

N-(6-Amino-3,4-dihydro-3-methyl-5-nitroso-4-oxopyrimidin-2-yl) derivatives of glycine, valine, serine, threonine and methionine: interplay of molecular, molecular–electronic and supramolecular structures

2000 ◽  
Vol 56 (5) ◽  
pp. 882-892 ◽  
Author(s):  
J. N. Low ◽  
M. D. López ◽  
P. Arranz Mascarós ◽  
J. Cobo Domingo ◽  
M. L. Godino ◽  
...  
Keyword(s):  
Hydrogen Bonds ◽  
Three Dimensional ◽  
Computational Modelling ◽  
Carboxyl Groups ◽  
Molecular Electronic ◽  
Database Analysis ◽  
Intermolecular Hydrogen Bonds ◽  
Bond Lengths ◽  
The Relationship ◽  
Derivatives Of

In each of N-(6-amino-3,4-dihydro-3-methyl-5-nitroso-4-oxopyrimidin-2-yl)valine, C10H15N5O4 (3) (orthorhombic, P212121), N-(6-amino-3,4-dihydro-3-methyl-5-nitroso-4-oxopyrimidin-2-yl)serine monohydrate, C8H11N5O5·H2O (4) (orthorhombic, P212121), and N-(6-amino-3,4-dihydro-3-methyl-5-nitroso-4-oxopyrimidin-2-yl)threonine, C9H13N5O5(5) (monoclinic, P21), the C-nitroso fragments exhibit almost equal C—N and N—O bond lengths: the C—N range is 1.315 (3)–1.329 (3) Å and the N—O range is 1.293 (3)–1.326 (3) Å. In each compound there are also very short intermolecular O—H...O hydrogen bonds, in which carboxyl groups act as hydrogen-bond donors to the nitrosyl O atoms: the O...O distances range from 2.440 (2) to 2.504 (4) Å and the O—H...O angles lie between 161 and 163°. An interpretation of the relationship between the unusual intramolecular bond lengths and the very short intermolecular hydrogen bonds has been developed based on database analysis and computational modelling. In each of (3)–(5) there is an extensive network of intermolecular hydrogen bonds, generating three-dimensional frameworks in (3) and (5), and two-dimensional sheets in (4).

STUDY OF INVARIANT Tc IN HIGHER DOPING LEVEL Y1-xCaxBa2-xLaxCu3Oy

2005 ◽  
Vol 19 (01n03) ◽  
pp. 307-309 ◽  
Author(s):  
X. F. SUN ◽  
H. L. DU ◽  
X. F. RUI ◽  
L. ZHANG ◽  
F. WANG ◽  
...  
Keyword(s):  
Structural Change ◽  
Carrier Concentration ◽  
Doping Level ◽  
Narrow Range ◽  
Bond Lengths ◽  
The Relationship

The higher doping level Y 1-x Ca x Ba 2-x La x Cu 3 O y samples were synthesized with x from 0.25 to 0.55. Structure and superconductivity have been investigated. Comparing with the results of lower doping level, the Tc of these samples keeps almost constant when dopant increasing. While some structural characters, such as Cu (1)- O (4), Cu (2)- O (4) bond lengths change randomly in a narrow range. The relationship between Ba / La position and Tc is rather interesting. The results give another evidence that the influence of structural change on superconductivity is independent of carrier concentration.

Charge Transfer and Bond Lengths in YBa2Cu3−xMxO6+y

1989 ◽  
Vol 156 ◽  
Author(s):  
P. F. Miceli ◽  
J. M. Tarascon ◽  
L. H. Greene ◽  
P. Barboux ◽  
J. D. Jorgensen ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Neutron Scattering ◽  
Bond Valence ◽  
Bond Lengths ◽  
The Relationship

ABSTRACTWe discuss the effects of doping on the Cu chain sites in YBa2Cu3−xMxO6+y. The relationship between bond lengths obtained from neutron scattering and charge transfer is evaluated in terms of bond valence. In particular, it is concluded that removing an oxygen from the chains transfers one electron to the planes.

scholarly journals The relationship between shape resonances and bond lengths

1987 ◽  
Vol 86 (5) ◽  
pp. 2765-2771 ◽  
Author(s):  
M. N. Piancastelli ◽  
D. W. Lindle ◽  
T. A. Ferrett ◽  
D. A. Shirley
Keyword(s):  
Bond Lengths ◽  
The Relationship ◽  
Shape Resonances

The solid-state molecular structure of W(NO)3Cl3 and the nature of its W—NO bonding

2004 ◽  
Vol 82 (2) ◽  
pp. 285-292 ◽  
Author(s):  
Trevor W Hayton ◽  
Brian O Patrick ◽  
Peter Legzdins ◽  
W Stephen McNeil
Keyword(s):  
Molecular Structure ◽  
Solid State ◽  
Dft Calculations ◽  
Diffraction Analysis ◽  
Mirror Plane ◽  
Ambient Conditions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Bond Lengths ◽  
Complex Solutions

The monomeric trinitrosyl complex, W(NO)3Cl3, can be prepared by the treatment of WCl6 in CH2Cl2 with NO gas, and its identity has been unambiguously confirmed by a single-crystal X-ray diffraction analysis. The complex crystallizes in the space group Pmn21 as a three-component twin (a = 10.4280(4) Å, b = 6.3289(2) Å, c = 5.6854(2) Å, Z = 2, R1 = 0.065, wR2 = 0.176). Its solid-state molecular structure consists of a tungsten centre bound to three chloride ligands and three linear nitrosyl ligands in a fac-octahedral stereochemistry. In addition, the structure contains a crystallographically imposed mirror plane. The two independent W—N linkages are 1.88(2) and 1.92(1) Å long, while the two corresponding N—O bond lengths are 1.13(2) and 1.16(2) Å. DFT calculations on fac-W(NO)3Cl3 at the B3LYP/LANL2DZ level of theory afford optimized intramolecular metrical parameters that match the X-ray crystallographically determined bond lengths and bond angles quite well. In addition, they provide a rationale for the nearly linear W-N-O linkages extant in the complex. Solutions of fac-W(NO)3Cl3 in CH2Cl2 lose ClNO under ambient conditions and deposit the well-known [W(NO)2Cl2]n polymer, and this conversion is fully reversible.Key words: nitrosyl, tungsten, structure, bonding.

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