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.

CHARACTERISTIC VIBRATIONAL FREQUENCIES OF COMPOUNDS CONTAINING Si—O—Si, P—O—P, S—O—S, AND Cl—O—Cl BRIDGING GROUPS FORCE CONSTANTS AND BOND ORDERS FOR THE BRIDGE BONDS

1964 ◽  
Vol 42 (11) ◽  
pp. 2496-2503 ◽  
Author(s):  
R. J. Gillespie ◽  
E. A. Robinson
Keyword(s):  
Vibrational Spectra ◽  
Electron Pair ◽  
Vibrational Frequencies ◽  
Force Constants ◽  
Bond Orders ◽  
Characteristic Frequencies ◽  
Bond Lengths ◽  
Isoelectronic Series ◽  
Empirical Rule ◽  
Bridging Groups

The assignment of characteristic frequencies for the X—O—X group in compounds containing Si—O—Si, P—O—P, S—O—S, and Cl—O—Cl bonds is discussed with reference to the vibrational spectra of disiloxanes, diphosphoryl, and disulphuryl compounds and dichlorine heptoxide. The stretching force constants of the X—O—X bridging bonds have been obtained by treating the molecules as simple triatomic species X2O• X—O bond orders and bond lengths have been calculated from the stretching force constants and the calculated and observed bond lengths are compared. The variation in the observed X—O—X angles is related to the bond orders and is discussed in terms of the electron-pair repulsion theory. It is shown that bond orders in the isoelectronic series Si2O76−, P2O74−, S2O72−, and Cl2O7 may be simply deduced from the empirical rule that the valency shell of a second-row element tends to be occupied by twelve electrons (the duodecet rule).

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.

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.

Kinematical evaluation of force constants: application to trihalides of phosphorus and arsenic

1970 ◽  
Vol 23 (5) ◽  
pp. 881 ◽  
Author(s):  
SN Rai ◽  
SN Thakur
Keyword(s):  
Force Constant ◽  
Vibrational Frequencies ◽  
Force Constants ◽  
Arbitrary Parameter ◽  
Two Dimensional ◽  
Matrix Elements ◽  
Bending Force ◽  
Symmetry Species

The F-matrix elements for the two-dimensional symmetry species are dependent on one arbitrary parameter in addition to the vibrational frequencies. This parameter has been chosen as an angle � (0 ≤ � ≤ 2π) and the F-matrix elements for the A1- and the E-species of trihalides of phosphorus and arsenic have been studied as functions of �. It is found that the best values of the force constants obtained from Coriolis 1; constants can be correlated with those values of the angle ξ for which the bending force constant exhibits a minimum.

Ein Iterationsverfahren zur Berechnung von Kraftkonstanten aus Grundschwingungsfrequenzen

1970 ◽  
Vol 25 (8-9) ◽  
pp. 1274-1280
Author(s):  
W. Hüttner
Keyword(s):  
Least Squares ◽  
Force Constant ◽  
Vibrational Frequencies ◽  
Force Constants ◽  
Normal Equations

Abstract A method for the adjustment of force constants from vibrational frequencies is presented. It re-presents an alternative to the various types of least-squares procedures which are widely used in force constant calculations, and avoids some of the well-known divergence difficulties which may occur in such least-squares iterations. Solving a system of normal equations is replaced by two simpler operations which cannot become ill-conditioned by singularities. The method applies preferably to cases where the number of excess data is small or zero.

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.

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.

Vibrational Spectra of the Hexacarbonyl Manganese(I) Cation

1974 ◽  
Vol 52 (2) ◽  
pp. 213-215 ◽  
Author(s):  
R. A. N. McLean
Keyword(s):  
Force Constant ◽  
Raman Spectra ◽  
Vibrational Spectra ◽  
Vibrational Frequencies ◽  
Force Constants ◽  
Infrared And Raman Spectra

The infrared and Raman spectra of the hexacarbonylmanganese cation as Mn(CO)6+ PF6− were assigned by comparison with other hexacarbonyl species. The CO stretching force constants for Mn(CO)6+ and Re(CO)6+ as indicated by the CO stretching vibrational frequencies are not significantly different. However, the Mn—C force constant in Mn(CO)6+ is likely to be considerably less than the Cr—C force constant in Cr(CO)6, whereas Re(CO)6+ and W(CO)6 have similar values. It is postulated that, although Mn(CO)6+ has equal metal–carbon σ bonding to Re(CO)6+, the metal-carbon σ bonding is less for Mn(CO)6+.

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