Bond length alternation in cyclic polyenes. IV. Finite-order purturbation theory approach

1984 ◽  
Vol 25 (2) ◽  
pp. 423-443 ◽  
Author(s):  
J. Paldus ◽  
M. Takahashi
Keyword(s):  
Bond Length ◽  
Finite Order ◽  
Theory Approach ◽  
Bond Length Alternation ◽  
Cyclic Polyenes

Approximate Molecular Orbital Theory: The Hückel/Tight-binding Model

2020 ◽  
pp. 231-245
Author(s):  
Jochen Autschbach
Keyword(s):  
Bond Length ◽  
Molecular Orbital ◽  
Tight Binding ◽  
Molecular Orbital Theory ◽  
Orbital Theory ◽  
Bond Length Alternation ◽  
Binding Model ◽  
Linear Polyenes ◽  
Benzene Structure ◽  
Cyclic Polyenes

Huckel molecular orbital (HMO) theory is a simple approximate parameterized molecular orbital (MO) theory that has been very successful in organic chemistry and other fields. This chapter introduces the approximations made in HMO theory, and then treats as examples ethane, hetratriene and other linear polyenes, and benzene and other cyclic polyenes. The pi binding energy of benzene is particularly large according to HMO theory, rationalizing the special ‘aromatic’ behaviour of benzene. But there is a lot more to benzene than that. It is shown that the pi bond framework of benzene would rather prefer a structure with alternating single and double C-C bonds, rather than the actually observed 6-fold symmetric structure where all C-C bonds are equivalent. The observed benzene structure is a result of a delicate balance between the tendencies of the pi framework to create bond length alternation, and the sigma framework to resist bond length alternation.

A New Class of Cyanine-like Dyes with Large Bond-Length Alternation

2009 ◽  
Vol 131 (17) ◽  
pp. 6099-6101 ◽  
Author(s):  
Shino Ohira ◽  
Joel M. Hales ◽  
Karl J. Thorley ◽  
Harry L. Anderson ◽  
Joseph W. Perry ◽  
...  
Keyword(s):  
Bond Length ◽  
Bond Length Alternation ◽  
New Class

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.

Bond length alternation and aromaticity in large annulenes

1998 ◽  
Vol 108 (16) ◽  
pp. 6681-6688 ◽  
Author(s):  
Cheol Ho Choi ◽  
Miklos Kertesz
Keyword(s):  
Bond Length ◽  
Bond Length Alternation
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