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Title: Bond Order-Length Relationships

 

Author: H. O. Jenkins

 

Affiliation: The University Manchester, England

 

Journal of American Chemical Society, 1955, 77(11), pp 3168-31-69

 

 

Summary

 

In this paper, an empirical relation between bond order and bond length has been presented which is very helpful to investigate a molecule or prepare system for molecular dynamics in the cases where bond length for a pair of atoms is unknown. The relation between bond order-length has been established by molecular orbital theory. In a bond order-length relationship, bond order is plotted against bond length and empirical equations are derived.

For hydrogen molecule the bond length (r_e) is 0.74 A and bond order (n) is 1, and for hydrogen molecule ion, the bond length (r_e) is 1.06 A and bond order (n) is 0.5. The inverse of the squares of bond lengths (1/r_e²) for the two species are 1.826 and 0.890 which suggests that bond order and 1/r_e² have some relationship. The bond lengths in ethane, ethylene, and acetylene are 1.543 A, 1.353 A, and 1.207 A. This C-C bond length in benzene is 1.397 A and its bond order has been reported as 1.67. Using a plot of bond order against bond length a straight line is obtained giving an empirical equation given below.

Table I shows a comparison of bond lengths computed using above formula and from literature. Similarly, C-N bond length comparison has been shown in table II.

 

Reviewer: Aamir Alaud Din