A Correlation between Bond Length and Ionic Bond Order. Application to the Ylide–Ylene Problem

1975 ◽  
Vol 53 (20) ◽  
pp. 3040-3043 ◽  
Author(s):  
Myung-Hwan Whangbo ◽  
Saul Wolfe ◽  
Fernando Bernardi
Keyword(s):  
Bond Length ◽  
Bond Order ◽  
The Other ◽  
Atomic Charges ◽  
Bond Orders ◽  
Ionic Bond ◽  
Molecular Systems ◽  
Bond Lengths ◽  
Coulombic Repulsion ◽  
Overlap Population

The C—O and C—S bond lengths of the cations, radicals, and anions CH3O, CH3S, CH2OH, and CH2SH have been found not to correlate with the overlap populations of the C—X bonds. On the other hand, very satisfactory linear relations are observed with the ionic bond orders of the C—X bonds. It is suggested that, in certain molecular systems, it may be more meaningful to associate shortening of a bond A—B with greater coulombic attraction (or smaller coulombic repulsion) between the two point charges represented by the net atomic charges on the atoms A and B than with an increase in the overlap population between these atoms. It is noted that such an interpretation can account for the short C—P bond in a phosphonium ylide without resort to (p → d)π conjugation.

Bond order-bond length relationships in conjugated hydrocarbons - the microwave spectrum and structure of 3,4-dimethylenecyclobutene

1983 ◽  
Vol 36 (4) ◽  
pp. 639 ◽  
Author(s):  
RD Brown ◽  
PD Godfry ◽  
BT Hart ◽  
AL Ottrey ◽  
M Onda ◽  
...  
Keyword(s):  
Dipole Moment ◽  
Ab Initio ◽  
Bond Length ◽  
Bond Order ◽  
Microwave Spectrum ◽  
Basis Set ◽  
Molecular Orbital Calculations ◽  
Bond Orders ◽  
Bond Lengths ◽  
Typical Error

The microwave spectrum of the benzene isomer 3,4-dimethylenecyclobutene including spectra of all possible single 13C-substituted and sufficient singly and doubly D-substituted species to give a complete r5 geometry, have been measured and analysed. An estimate of the re geometry has also been derived. The additional precise CC bond lengths obtained for an unsubstituted, conjugated hydrocarbon enable us to examine bond order-bond length relationships more thoroughly than has previously been possible. The CC bond lengths exhibit a noticeably better correlation with SCFMO bond orders than with simple H�ckel bond orders. Further confirmatory measurements of the dipole moment of dimethylenecyclobutene have been made. Ab initio molecular orbital calculations using a 6-31G basis set give an optimized geometry with CC bond lengths within 2 pm of the r5 values. The computed dipole moment agrees almost exactly with experiment but a corresponding calculation on fulvene is discrepant with experiment by 0.16 D, which is probably a more typical error.

scholarly journals Bond lengths in naphthalene and anthracene

1951 ◽  
Vol 207 (1090) ◽  
pp. 306-320 ◽  
Keyword(s):  
Aromatic Hydrocarbon ◽  
Bond Length ◽  
Configuration Interaction ◽  
Bond Order ◽  
Bond Orders ◽  
Bond Lengths ◽  
Self Consistent ◽  
Hydrocarbon Molecules ◽  
Experimental Values ◽  
Correction Terms

An extremely careful inquiry is made into the possibility of predicting bond lengths in condensed aromatic hydrocarbon molecules. Agreement with the best experimental values, such as those of Robertson, Abrahams, White, Mathieson and Sinclair, is fairly easily obtained to an accuracy of about 0.02Å. This shows that the concept of fractional bond order may quite properly be used to infer bond lengths. Both the molecular-orbital and resonance methods are equally good for this purpose. Predictions to within less than 0.02Å require the introduction of new factors usually neglected. No less than five such factors are discussed: ( а ) electrostatic forces, arising from possible differences in electronegativity of the various carbon atoms, ( b ) changes of bond orders due to electronegativity differences, ( c ) variation of resonance integrals with bond length, ( d ) obtaining a self-consistent set of resonance integrals, ( e ) inclusion of configuration interaction. Correction terms which result from these improvements lie between 0 and 0.015Å, and are not all of the same sign. It is unlikely therefore that this type of analysis will be able to give confident predictions of bond lengths to less than 0.01Å.

THE SULPHUR–OXYGEN BOND IN SULPHURYL AND THIONYL COMPOUNDS: CORRELATION OF STRETCHING FREQUENCIES AND FORCE CONSTANTS WITH BOND LENGTHS, BOND ANGLES, AND BOND ORDERS

1963 ◽  
Vol 41 (8) ◽  
pp. 2074-2085 ◽  
Author(s):  
R. J. Gillespie ◽  
E. A. Robinson
Keyword(s):  
Bond Length ◽  
Linear Relationship ◽  
Force Constant ◽  
Bond Order ◽  
Bond Angle ◽  
Bond Orders ◽  
Bond Angles ◽  
Bond Lengths ◽  
Frequency Relationship ◽  
Oxygen Bond

It is shown that the bond length of an SO bond and the bond angle of an SO2 group may be very satisfactorily correlated with the SO stretching frequency. The bond-length – stretching-frequency relationship is used to predict some bond lengths that have not been measured and the OSO angles in some sulphuryl compounds are also calculated. The problem of defining and measuring the bond order of sulphur–oxygen bonds is discussed. It is shown that there is a linear relationship between the force constant and the bond order and a non-linear relationship between the bond length and the bond order.

scholarly journals Atomic Charges, Surface Electrostatic Potential Analysis, and Bond Order Analysis on Nitriles and Isocyanides

2021 ◽  
Author(s):  
Yanyun Zhao ◽  
Xueli Cheng
Keyword(s):  
Electrostatic Potential ◽  
Bond Order ◽  
Atomic Charges ◽  
Bond Orders ◽  
Potential Analysis ◽  
Order Analysis ◽  
Population Analyses ◽  
Full Optimization ◽  
Global And Local ◽  
Surface Electrostatic Potential

Abstract Isocyanide-nitrile rearrangement has long been a continuing and interesting topic. A series of nitriles and isocyanides with the substituents of R=-AlH2, -BeH, -BH2, -C ≡ CH, -CF3, -CH3, -Cl, -C ≡ N, -COOH, -F, -H, Li, -MgH, -Na, -NH2, -NO2, -OH, -PH2, -SH, -SiH3, -CH = CH2 were investigated systematically based on full optimization at B3LYP-D3(BJ)/def2-QZVP level, and the isomerization energies from R-C ≡ N to :C = N-R were estimated. The substituent effect and bonding characters were analyzed by surface ESP colored van der Waals surfaces in conjunction with the global and local electrostatic extrema, the population analyses in terms of Hirshfeld and ADCH atomic charges, and bond order analyses via Laplacian and fuzzy bond orders.

CHARACTERISTIC VIBRATIONAL FREQUENCIES OF OXYGEN COMPOUNDS OF SILICON, PHOSPHORUS, AND CHLORINE: CORRELATION OF STRETCHING FREQUENCIES AND FORCE CONSTANTS WITH BOND LENGTHS AND BOND ORDERS

1963 ◽  
Vol 41 (12) ◽  
pp. 3021-3033 ◽  
Author(s):  
E. A. Robinson
Keyword(s):  
Bond Length ◽  
Force Constant ◽  
Chlorine Atom ◽  
Silicon Atom ◽  
Vibrational Frequencies ◽  
Force Constants ◽  
Bond Orders ◽  
Present Treatment ◽  
Bond Lengths ◽  
Linear Correlations

For oxygen compounds of chlorine, phosphorus, and silicon, respectively, correlations are established between stretching frequencies and force constants of Cl—O, P—O, and Si—O bonds, and their bond lengths.By deducing bond orders on the assumption that only [Formula: see text]and [Formula: see text] orbitals on the central chlorine, phosphorus, or silicon atom are utilized in the formation of double bonds with lone pairs of electrons on oxygen, linear correlations between bond orders and force constants are established.The present treatment leads to the conclusion that the presence of a maximum of 12 electrons in the valency shells of chlorine, phosphorus, and silicon is required to best explain the bond length and force constant data, when highly electronegative ligands such as oxygen or fluorine are attached to the central silicon, phosphorus, or chlorine atom.

Bond length–bond order relations and calculated geometries for some benzenoid aromatics, including phenanthridine. Structures of 5,6-dimethylphenanthridinium triflate, [N-(6-phenanthridinylmethyl)-aza-18-crown-6-κ5 O,O',O'',O''',O''''](picrate-κ2-O,O')potassium, and [N,N'-bis(6-phenanthridinyl-κN-methyl)-7,16-diaza-18-crown-6-κ4 O,O',O'',O''']sodium iodide dichloromethane solvate

1996 ◽  
Vol 52 (5) ◽  
pp. 823-837 ◽  
Author(s):  
R. Kiralj ◽  
B. Kojić-Prodić ◽  
M. Žinić ◽  
S. Alihodžić ◽  
N. Trinajstić
Keyword(s):  
Bond Length ◽  
Bond Order ◽  
Alkali Metals ◽  
Sodium Iodide ◽  
Complex Cation ◽  
Molecular Orbital Calculations ◽  
Benzenoid Hydrocarbons ◽  
Molecular Mechanics Calculations ◽  
Bond Lengths ◽  
Order Relations

The crystal structures of the title compounds are studied in order to investigate the role of novel fluoroionophores in complexation of sodium and potassium. In the potassium complex seven coordination, including the picrate ligand, is encountered. An additional coordination site is via the phenanthridine nitrogen at 3.252 (2) Å (second coordination). The complex is of C 1 symmetry and the aza-18-crown-6 macrocylic ring exhibits a crown-type conformation. The 7,16-diaza-18-crown-6 macrocycle accommodates a six-coordinate sodium with two additional ligands, via nitrogen from phenanthridine units. The complex cation shows a crystallographic twofold symmetry. The macrocycle is not of the crown-type conformation. In both complexes the alkali metals are shifted out of the cavity centres towards a picrate ligand in [N-(6-phenanthridinylmethyl)-aza-18-crown-6-κ5 O,O′,O′′,O′′′,O′′′′](picrate-κ2 O,O′)potassium and the phenanthridine units in [N,N′-bis-(6-phenanthridinyl-κN-methyl)-7,16-diaza-18-crown-6-κ4 O,O′,O′′,O′′′]sodium iodide dichloromethane solvate. Semi-empirical and molecular mechanics calculations based on various force fields were used for the optimization of phenanthridine geometry. The values obtained are compared with experimental data. Valence bond calculations of bond lengths in some benzenoid aromatic systems (C—C bonds in benzenoid hydrocarbons, azabenzenoid hydrocarbons and picrate-like systems; C—N bonds in the azabenzenoids; C—O bonds in the picrate-like systems), as well as some analogous Hückel molecular orbital calculations (C—C bonds in the benzenoid hydrocarbons and the azabenzenoids), were found to agree with the observed values (average differences up to 0.015 Å). These approaches can be used by means of bond length-bond order relations for prediction of bond lengths in the phenanthridine units as well as in the picrate.

The crystal and molecular structure of the copper(II) bis(dialyldithiocarbamate) complex

1984 ◽  
Vol 49 (10) ◽  
pp. 2210-2221 ◽  
Author(s):  
Eleonóra Kellö ◽  
Victor Kettmann ◽  
Ján Garaj
Keyword(s):  
Crystal Structure ◽  
Bond Length ◽  
Least Squares Method ◽  
Crystal And Molecular Structure ◽  
The Other ◽  
Tetragonal Pyramid ◽  
X Ray ◽  
Bond Lengths ◽  
Triclinic System ◽  
Bond Character

The crystal structure of {Cu[S2CN(C3H5)2]2}2 was solved by the single crystal method of X-ray structural analysis. The substance crystallized as a dimer in the triclinic system with space group of PI and latice parameters a = 1.0161 (4), b =0.9294(4), c = 1.0518(3) nm, α = 77.46(3), β = 77.10(3), γ = 89.02(3)°. The structure was refined by the least squares method to a final value of R = 4.9% using all the 1 713 observed reflections. The crystal structure consists of dimeric molecules, where each pair of centrosymmetrically dependent Cu atoms lies at a distance of 0.3742 nm. The coordination polyhedron of the Cu atom is a tetragonal pyramid, where the four sulphur atoms lie at distances of Cu-S1 0.2314, Cu-S2 0.2309, Cu-S3 0.2324, Cu-S4 0.2328 and are approximately in a place from which the Cu atoms lies at a distance of 0.026 nm. The fifth, longer bond, Cu-S'4 0.2888 nm forms the apex of the tetragonal pyramid. In the streochemistry of the dithiocarbamate ligands of the studied substances there are no marked differences in the bond lengths and corresponding angles compared with the values for the solvent structures of the other dialkyl-dtc complexes. The lengths of the sulphur-carbon bonds lie in the range from 0.170 to 0.173 nm and both lengths of the C(sp)2 - N(sp2) bonds equal to 0.134 and 0.133 nm indicate marked double bond character of the C-N bond. The S2CN ligand fragment is planar. In the alyl part of the ligand, the N-C bond lengths lie in the range 0.147-0.149 nm, the average C-C bond length is 0.149 nm and C=C bond length is 0.132 nm.

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