and meso-NaDMGA, the change is caused only by the effect of substituents (or by the effect of solvents), since the conformation is found to be fixed over all degrees of neutralization. In the case of isotactic P(NaMA), however, we were unable to decide between the two possibilities, since the vicinal coupling constants are not known. It is at least probable, however, that the effect of the substituent should be most important for the change in < >. In any case, it is certain that the effect of the substituent or the

No abstract

No abstract

Na43+ ionic clusters, probably located inside sodalite cages, are formed when zeolite Na+-Y is exposed to Na or K vapour and K43+ clusters when K+-Y is exposed t o the vapour of Na or K, but Rbq3+ cannot be observed (by e.s.r. spectroscopy) using Rb+-Y under comparable conditions; at higher concentrations of metal vapour intracrystalline metallic particles are formed.

No abstract