Bond length variations

Index of aromaticity based c bond-length variation (benzene = 100). ... 

Further, if a certain distorted structure and its countertype in which the bond-length variation is reversed are not equivalent (e. g., the two Kekule-type structures in IV), these two structures should be differentiated as a starting geometry. 

Table 17. Average metal-ligand bond lengths R for HS and LS isomers and bond length variation AR for complete HS <-> LS conversion of spin transition compounds...

W. H. Baur, Bond length variation and distorted coordination polyhedra in inorganic crystals. Trans. Am. Crystallogr. Assoc. 6 (1970) 129. 

McKean, D. C., J. E. Boggs, and L. Schafer. 1984. CH Bond Length Variations Due to the Intramolecular Environment a Comparison of the Results Obtained by the Method of Isolated CH Stretching Frequencies and by Ab Initio Gradient Calculations. J. Mol. Struct. 116, 313-330. 

The computational bond-length variations in Table 4.53 exhibit the expected periodic trends. Most noticeably, third- and second-series elements for groups 4, 6, and 10 exhibit similar bond lengths, i.e., the post-lanthanide contraction with respect to the ordinary increase of atomic size with increasing Z. 

These bond length variations have been rationalized in terms of different degrees of ring 7t-bonding within a molecule. Strong electronegative substituents contract the d-orbital at the phosphorus atom and make them less available for... 

Boison, M. B., Gibbs, G. V., and Zhang, Z. G. (1988). Resonant bond numbers A graph theoretic study of bond length variations in silicate crystals. Phys. Chem. Miner. 15, 409-15. 

Table 4 Bond Length Variation with Oxidation State in Hexaorganoisocyanide and...

A comparison of metal-metal bond-length variations for a given metal in differing environments among structures of homonuclear rhenium, molybdenum, and chromium dimers reveals that the flexibility of strong multiple chromium-chromium bonds is distinctly different from the behavior of the two heavier metals. Both rhenium and molybdenum display relatively constant quadruple bond lengths in most structures examined to date, while chromium exhibits a wide range of metal-metal distances. 

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