Rotational strengths experimental values

Finally, on carrying the treatment of the concunent T2 and T2g crystal field potentials to all orders of perturbation theory, it has been established ), for a wide range of parameter sets, that the computed rotational strengths are at variance quantitatively and in qualitative form with the conesponding experimental values, measured from the CD band areas. In particular, the rotational strengths of the d—d transitions to the D3 cobalt(IIl) states, A2 and E with a common octahedral parent-... 

How do these predictions of the ir-bond strength compare with experimental values We can measure the energy required to interconvert the cis form of a substituted alkene—say, 1,2-dideuterioethene— with its trans isomer. In this process, called thermal isomerization, the two p orbitals making up the tt bond are rotated 180°. At the midpoint of this rotation— 90°—the ir (but not the a) bond has been broken (Figure 11-6). Thus, the activation energy for the reaction can be roughly equated with the ir energy of the double bond. 

Figure 2 Comparison of calculated and experimental rotational strengths for (1R, 4R)-(+)-camphor. R values are in 10- esu cm. The straight line has a slope +1.

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