Propellanes Laplacian

Fig. 3 Correlation of the covalent Laplacian (L) with the value of D ov for homonuclear bonds. The CSBs are concentrated in the upper left quadrant, while the classical covalent bonds are in the lower right quadrant. Note the two bond types of [1.1.1] propellane, each belonging to a different quadrant. Reproduced from [10] with permission of Wiley-VCH...

Fig. 13 A two-dimensional plot of /f cov-ion/C m-situ (calculated by VB theory) vs. the Laplacian L (calculated by AIM, in atomic units) at the BCP for the target C-C bonds in 1-13 (Scheme 5), with vertical lines drawn to emphasize the separation into two families of C-C bonds. The substituted [l.l.l]-X3-propellanes (4-10 in Scheme 5) are specified by their wing fragment X (X=CH2, NH, etc.). Reprinted from Fig. 5 in [13] with permission of Wiley-VCH...

The existence of the CS bond family will eventually be cmisolidated by experimental means. One such technique involves the determination of the Laplacian of various bonds from experimental densities, as already done for propeUane [58], N2O4 [73], (Mg-Mg) " cores [74], etc. [56, 57]. Thus, as we already alluded to, for [l.l.l]propellane derivatives [58], the experimental Laplacian clearly shows the existence of a classical covalent C-C bond in the wing positions vis-a-vis a CS C-C bond in the inverted bond region. Such experimental characterization for other bonds will further show the importance of this new bond family. 

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