scholarly journals Relations among Bond Order, Force Constant and Bond Length for the C–C and the C–N Bond in Conjugated Molecules

1957 ◽  
Vol 30 (6) ◽  
pp. 638-647 ◽  
Author(s):  
Tosinobu Anno ◽  
Mitsuo Ito ◽  
Ryoichi Shimada ◽  
Akira Sado ◽  
Wataru Mizushima
Keyword(s):  
Bond Length ◽  
Force Constant ◽  
Bond Order ◽  
Conjugated Molecules

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 An investigation of the interrelationships between linear and nonlinear polarizabilities and bond-length alternation in conjugated organic molecules

1993 ◽  
Vol 90 (23) ◽  
pp. 11297-11301 ◽  
Author(s):  
C B Gorman ◽  
S R Marder
Keyword(s):  
Bond Length ◽  
Organic Molecules ◽  
Computational Method ◽  
Bond Length Alternation ◽  
Conjugated Molecules ◽  
Conjugated Organic Molecules ◽  
Alpha Beta ◽  
Relationship Of ◽  
The Relationship ◽  
Observable Parameter

A computational method was devised to explore the relationship of charge separation, geometry, molecular dipole moment (mu), polarizability (alpha), and hyperpolariz-abilities (beta, gamma) in conjugated organic molecules. We show that bond-length alternation (the average difference in length between single and double bonds in the molecule) is a key structurally observable parameter that can be correlated with hyperpolarizabilities and is thus relevant to the optimization of molecules and materials. By using this method, the relationship of bond-length alternation, mu, alpha, beta, and gamma for linear conjugated molecules is illustrated, and those molecules with maximized alpha, beta, and gamma are described.

Molecular orbital calculations for conjugated molecules containing boron and nitrogen

1967 ◽  
Vol 45 (18) ◽  
pp. 2059-2070 ◽  
Author(s):  
N. C. Baird ◽  
M. A. Whitehead
Keyword(s):  
Molecular Orbital ◽  
Bond Order ◽  
Molecular Orbital Calculations ◽  
Conjugated Molecules ◽  
Boron Nitrogen

The Π-electron networks in boron–nitrogen chains and rings have been treated by l.c.a.o.–m.o. techniques. The results for B—N chains predict a very weak alternation of bond order, smaller charges on the terminal atoms than on the internal atoms, and very little conjugation across B—B and N—N linkages. The calculations for the B—N rings predict an absence of a "4n + 2" pi-electron rule for aromaticity and a predominance of exocyclic over endocyclic Π bonding in the substituted rings. These results are compared with the properties of known B—N chains and rings and are contrasted with l.c.a.o.–m.o. calculations for the analogous carbon–carbon systems.

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.

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