Dihedral Angles of the Cycloheptane Ring

1988 ◽  
Vol 41 (7) ◽  
pp. 1139 ◽  
Author(s):  
GA Bottomley
Keyword(s):  
Membered Ring ◽  
Dihedral Angles ◽  
Bond Angles ◽  
Bond Lengths ◽  
Tetrahedral Bond

A method is described for calculating sets of dihedral angles in a seven- membered ring with equal tetrahedral bond angles and equal bond lengths. Representative values are given for the separate chair and boat manifolds of solutions.

scholarly journals (4-Chloroacetanilido-κ2N,O)bis[2-(pyridin-2-yl)phenyl-κ2C1,N]iridium(III)

2013 ◽  
Vol 69 (2) ◽  
pp. m98-m98
Author(s):  
Lijun Sun ◽  
Songlin Zhang ◽  
Qijun Song
Keyword(s):  
Dihedral Angle ◽  
Title Compound ◽  
Membered Ring ◽  
Octahedral Geometry ◽  
Dihedral Angles ◽  
Bond Lengths ◽  
Coordination Sites

In the neutral mononuclear iridium(III) title compound, [Ir(C8H7ClNO)(C11H8N)2], the IrIIIatom adopts an octahedral geometry, and is coordinated by two 2-phenylpyridyl ligands and one anionic 4-chloroacetanilide ligand. The 2-phenylpyridyl ligands are arranged in acis-C,C′ andcis-N,N′ fashion. Each 2-phenylpyridyl ligand forms a five-membered ring with the IrIIIatom. The 2-phenylpyridyl planes are perpendicular to each other [dihedral angle = 89.9 (1)°]. The Ir—C and Ir—N bond lengths are comparable to those reported for related iridium(III) 2-phenylpyridyl complexes. The remaining two coordination sites are occupied by the amidate N and O atoms, which form a four-membered ring with the iridium atom (Ir—N—C—O). The amidate plane is nearly perpendicular to both 2-phenylpyridyl ligands [dihedral angles = 87.8 (2) and 88.3 (2)°].

scholarly journals Crystal structure ofN′-[(E)-(1S,3R)-(3-isopropyl-1-methyl-2-oxocyclopentyl)methylidene]-4-methylbenzenesulfonohydrazide

2015 ◽  
Vol 71 (12) ◽  
pp. o904-o905 ◽  
Author(s):  
David Tymann ◽  
Dina Christina Dragon ◽  
Christopher Golz ◽  
Hans Preut ◽  
Carsten Strohmann ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Aromatic Ring ◽  
Title Compound ◽  
Membered Ring ◽  
Dihedral Angles ◽  
Relative Configuration ◽  
Bond Angles ◽  
Compound C ◽  
A Chain

The title compound, C17H24N2O3S, was synthesized in order to determine the relative configuration of the corresponding β-keto aldehyde. In the U-shaped molecule, the five-membered ring approximates an envelope, with the methylene C atom adjacent to the quaternary C atom being the flap, and the methyl and isopropyl substituents lying to the same side of the ring. The dihedral angles between the four nearly coplanar atoms of the five-membered ring and the flap and the aromatic ring are 35.74 (15) and 55.72 (9)°, respectively. The bond angles around the S atom are in the range from 103.26 (12) to 120.65 (14)°. In the crystal, molecules are linkedviaN—H...O hydrogen bonds, forming a chain along theaaxis.

Improved Molecular Model of a Peptide Unit for Proteins

2006 ◽  
Author(s):  
Raghavendran Subramanian ◽  
Kazem Kazerounian
Keyword(s):  
Molecular Model ◽  
Data Bank ◽  
Rigid Bodies ◽  
Peptide Chain ◽  
Dihedral Angles ◽  
Model Parameters ◽  
Bond Angles ◽  
Bond Lengths ◽  
Structural Error ◽  
Peptide Unit

Pauling, Corey and Branson in their seminal paper in 1951 reported numerical values for the bond lengths and bond angles for a peptide unit in proteins. These values became the standard model for several decades after that. This classic peptide model was either confirmed or improved upon by other researchers over the years, by using more advanced X-Ray diffraction equipments. In this paper, we have made an attempt to calibrate the values of these bond lengths and bond angles based on a systematic and deterministic approach applied to a collection of proteins defined structurally in the Protein Data Bank (PDB). Our method is based on the assumption that a peptide chain is a serial chain of identical rigid bodies connected by revolute joints (i.e. dihedral angles). The proposed procedure first computes the best estimate for the dihedral angles in the presence of inaccuracies in the atoms’ coordinates data. Then these values are used to find the conformation of the peptide chain using the calibrated model of the peptide unit. Through an optimization process, the structural error (RMSD of all atoms) between the resultant conformation and the PDB data is minimized to yield the best values for the bond length and bond angles in the calibrated peptide unit. Our numerical experiments indicate that by making small changes in the Pauling-Corey peptide model parameters (0.15% to 8.7%) the structural error is reduced significantly (3.0% to 57.4%). The optimum values for the bond angles and bond lengths are as follow: Bond Lengths: N-C(A): 1.4721Å, C(A)-C: 1.6167Å, C-N: 1.2047Å, C=O: 1.1913Å and N-H: 0.9621Å. Bond Bending Angles: N-C(A)-C: 109.6823°, C(A)-C=0: 119.518°, C(A)-C-N: 114.5553°, O=C-N: 125.9233°, C-N-H: 123.5155°, C-N-C(A): 121.5756°, C(A)-N-H: 114.901°. Peptide bond torsion angle: ω: 179.4432°.

Synthesis and Crystal Structures of Three Carboxylate- Bridged Tetranuclear Copper(II) - Lanthanide(III) Complexes of Ph3P+CH2CH2CO2−

1999 ◽  
Vol 52 (10) ◽  
pp. 983 ◽  
Author(s):  
Yang-Yi Yang ◽  
Seik Weng Ng ◽  
Xiao-Ming Chen
Keyword(s):  
Oxygen Atom ◽  
Crystal Structures ◽  
Triclinic Space Group ◽  
Coordination Environment ◽  
Space Group ◽  
Bond Angles ◽  
Bond Lengths ◽  
Metal Atoms ◽  
Apical Site

Three tetranuclear copper(II)–lanthanide(III) complexes of triphenylphosphoniopropionate (Ph3P+CH2CH2CO2−,tppp), namely [Cu2Ln2(tppp)8(H2O)8](ClO4)10·2H 2 O [Ln = EuIII, NdIII or CeIII], were synthesized and characterized by crystallography. The EuIII complex crystallizes in the triclinic space group P1 – with a 16.249(7), b 17.185(11), c 17.807(11) Å, α 69.750(10), β 89.230(10), γ 84.070(10)˚, V 4639(5) Å3, Z 1. In the crystal structures, four tppp ligands bridge a pair of CuII and tetraaquo-EuIII atoms (Cu···Eu 3.527(2) Å) through their µ2-carboxylato ends to form a dinuclear subunit; two of these subunits are additionally linked by one of the CuII -bonded carboxylato oxygen ends, across a centre of inversion, to furnish a dimeric tetranuclear [Cu(tppp)4 Eu(H2O)4]2 species (Cu···Cu 3.323(2) Å). This CuII -bonded oxygen atom occupies the apical site of the square-pyramidal coordination environment of the CuII atom. The EuIII atom is eight-coordinated in a square-antiprismatic geometry. The NdIII and CeIII complexes are isomorphous to the EuIII complex, and only minor differences in bond lengths and bond angles involving the metal atoms are noted.

Molecular orbital structures of sulfones

1982 ◽  
Vol 60 (6) ◽  
pp. 730-734 ◽  
Author(s):  
Russell J. Boyd ◽  
Jeffrey P. Szabo
Keyword(s):  
Crystal Structure ◽  
Gas Phase ◽  
Molecular Orbital ◽  
Geometry Optimization ◽  
Membered Ring ◽  
Molecular Orbital Calculations ◽  
Bond Lengths ◽  
Comparison With Experiment ◽  
The Difference

Abinitio molecular orbital calculations are reported for several cyclic and acyclic sulfones. The geometries of XSO2Y, where X, Y = H, F, or CH3 are optimized at the STO-3G* level. Similar calculations are reported for the smallest cyclic sulfone, thiirane-1,1 -dioxide, as well as the corresponding sulfoxide, thiirane-1-oxide, and the parent sulfide, thiirane. Where comparison with experiment is possible, the agreement is satisfactory. In order to consider the possibility of substantial differences between axial and equatorial S—O bonds in the gas phase, as observed in the crystal structure of 5H,8H-dibenzo[d,f][1,2]-dithiocin-1,1-dioxide, STO-3G* calculations are reported for a six-membered ring, thiane-1,1-dioxide, and a model eight-membered ring. Limited geometry optimization of the axial and equatorial S—O bonds in the chair conformations of the six- and eight-membered rings leads to bond lengths of 1.46 Å with the difference being less than 0.01 Å.

scholarly journals Structural Modeling of Glutathiones Containing Selenium and Tellurium

2016 ◽  
Vol 8 (1) ◽  
pp. 102
Author(s):  
Valter A. Nascimento ◽  
Petr Melnikov ◽  
André V. D. Lanoa ◽  
Anderson F. Silva ◽  
Lourdes Z. Z. Consolo
Keyword(s):  
Molecular Mechanics ◽  
Structural Characteristics ◽  
Structural Modeling ◽  
Structural Description ◽  
Ionic Radii ◽  
X Ray ◽  
Bond Angles ◽  
Bond Lengths ◽  
Available Information ◽  
Related Compounds

<p>The comparative structural modeling of reduced and oxidized glutathiones, as well as their derivatives containing selenium and tellurium in chalcogen sites (Ch = Se, Te) has provided detailed information about the bond lengths and bond angles, filling the gap in the structural characteristics of these tri-peptides. The investigation using the molecular mechanics technique with good approximation confirmed the available information on X-ray refinements for the related compounds. It was shown that Ch-H and Ch-C bond lengths grow in parallel with the increasing chalcogen ionic radii. Although the distances C-C, C-O, and C-N are very similar, the geometry of GChChG glutathiones is rich in conformers owing to the possibility of rotation about the bridge Ch-Ch. It is confirmed that the distances Ch-Ch are essentially independent of substituents in most of chalcogen compounds from elemental chalcogens to oxydized glutathiones. The standard program Hyperchem 7.5 has proved to be an appropriate tool for the structural description of less-common bioactive compositions when direct X-ray data are missing.</p>

Lattice parameters of Zn1−xMnxSe and tetrahedral bond lengths in AII1−xMnxBVIalloys

1985 ◽  
Vol 58 (11) ◽  
pp. 4056-4060 ◽  
Author(s):  
D. R. Yoder‐Short ◽  
U. Debska ◽  
J. K. Furdyna
Keyword(s):  
Lattice Parameters ◽  
Bond Lengths ◽  
Tetrahedral Bond
Sign in / Sign up

Export Citation Format

Share Document