Effects on Bond Length

We recall that the length of carbon-carbon O bonds depends on the hybridization of both carbon atoms. The bond length between the sp -hybridized methyl carbon atom and the sp -, sp -, and sp-hybridized central carbon atoms of propane, propene, and propyne, show this effect. The bond length for sp -sp bonded atoms, 151 pm, is 3 pm shorter than that of sp -sp bonded atoms. If there were no double bond character between C-2 and C-3 in butadiene, we might expect a bond length of 148 pm. However, the bond length of 1,3-butadiene is 146 pm. The molecular orbital model predicts a shorter bond length than would be expected from a Lewis structure because of the continuous overlap 

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Fig. 7. The influence of the Jahn-Teller effect on bond lengths (A) of copper sulfate trihydrate (top) and pentahydrate (bottom). Note that in the trihydrate one of the Cu(II)-"OSOs bonds is short so that all equatorial Cu(Il)-"0 bonds are 1.94-1.98 A, while the axial bonds are 2.40-2.45 A.

Table A5-58 Basis Set Effects on Bond Lengths in Hydrogen Bonded Complexes. 

The tuning of electron counts is one of the strategies of the solid state chemists. Elements can be substituted, atoms intercalated, nonstoichiometries enhanced. Oxidation and reduction, in solid state chemistry as in ordinary molecular solution chemistry, are about as characteristic (but experimentally not always trivial) chemical activities as one can conceive. The conclusions we reached for the Pt-Pt chain were simple, easily anticipated. Other cases are guaranteed to be more complicated. The COOP curves allow one, at a glance, to reach conclusions about the local effects on bond length (will bonds be weaker, stronger) upon oxidation or reduction. 

It has been suggested that there should be little or no effect on bond length when a methyl group attached to a carbon atom is replaced by a trifluoromethyl group [83JFC(23)147], Therefore, this transformation should result in minimal disruption to an enzyme-substrate complex [90AG(E)1320]. 

Figure 5. Relativistic effects on bond lengths and binding energies of group 4 tctrahydrides XH. The bond length contraction (in A) and bond destabilization (in eV) were obtained as the difference between relativistic Dirac-Hartree-Fock calculations based on the Dirac-Coulomb-Gaunt Hamiltonian and corresponding nonrelativistic Hartree-Fock calculations [28,29].

Spin-orbit effects on bond lengths, harmonic vibrational frequencies and dissociation energies of IH, AtH, and (117)H calculated with SC RECPs at various levels of theory. 

Spin-orbit effects on bond lengths at the Cl level are very similar to KRCC ones when the same RECPs are employed. We think that the shorter bond... 

From the data in Table 8, spin-orbit effects on bond lengths, harmonic vibrational frequencies and dissociation energies for (113)F were obtained, and listed in Table 15. The spin-orbit effects fi-om the one- and two-component REP results deviate somewhat from those from DK and DC based all-electron results. The spin-orbit effects evaluated by Seth et al. [78] from ARPP-SOCI calculations are also in overall better agreement with those from RECP than those from DK/DC results. The origin of the deviation is not clear, but spin-orbit effects are qualitatively similar enough to make the discussion of spin-orbit effects based on the RECP results valid. The variations in spin-orbit effects for R and (Og, obtained at various levels of theory by Seth et al, are uniformly smaller in comparison with other results both for (113)F and (113)H, which is probably due to... 

Bocca, C. C., Pontes, R. M., Basso, E. A. (2004). Implications of hyperconjugative effects on bond lengths of aUylic systems. A 7VA/0 investigation. Journal of Molecular Structure THEOCHEM, 710,105-110. 

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