| Popis: |
Spectroscopic force fields of benzene are shown to be compatible with the observed non-coplanarity of benzene rings with their H- or C- substituents in strained compounds, e.g. cyclophanes. A simplified force field for annulenes and cyclophanes is discussed, and ratios of the twist and out-of-plane bending force constants involved are derived from structural data. The resistance to twisting of partial double bonds is found to increase with decreasing bond length. Various formulae to calculate out-of-plane deformation coordinates are collected in an appendix. |
