In recent years many data have been accumulated demonstrating that the strain in polycyclic ring systems (originating either from non bonded interactions of substituents or from a change in hybridisation at one site of the molecule) 1 may be relieved by alteration of bond angles . In turn this leads to conforma: tional changes which -in special cases -can be detected by physical and/or chemical properties. For a description of this phenomenonLS' the term "confornational transmission" has been coined: It means propagation of bond angle distortion within the molecular frame, i.e. angle deformation induced at one site of the molecule causes a corresponding angle deformation at another more cr less remote site. Qur studies are concerned with systems where a partial compensation of a bond angle distortion is caused by an alteration of a torsional angle (at the same site) leaving all other bond and torsional -angles (and of course bond lengths) unchanged. This can only be the case if the system is rigid and contains at least one single bond about which torsion occurs. a.ametacxclophane (1) seems to fulfill these requirements: it consists of a rigid tenmembered-ring-system connecting two benzene rings which in addition furnish a powerful tool for detecting changes in molecular geometry via the 'H-NMR chemical shifts of the intraanular aryl protons. Recently 4 it has been demonstrated that the rather 1357 1358 Ilo. 15 unusual location of their resonance absorption can be satisfactorily explained in terms of ring current theory: taking into' account the puckered topology of the aromatic rings, no further assumptions are necessary for a quantitative interpretation. Therefore even subtle conformational changes should be reflected by the shift of these protons.