SIZE AND SHAPE OF MOLECULAR-IONS AND THEIR RELEVANCE TO THE PACKING OF THE SOFT SALTS

The manner in which inorganic molecules and ions pack in the solid sta te is critical in determining their conductivity, magnetic and non-lin ear optical properties. In a previous paper the methodology for calcul ating the volumes, surface areas, effective radii and shapes of inorga nic ions was developed. In this paper these structural parameters are used to rationalise the solid state structures of 'soft salts' which c onsist of a large cluster cation and a large cluster anion. The effect ive radii of the cluster ions derived from the volume contained within the van der Waals sphere of their atoms may be used to calculate radi us ratios for the salts which may be used to interpret the observed so lid state structures. The distortions from the idealised inorganic sal t structures have been related to the non-spherical nature of the ions , which have been calculated from their moments of inertia. The differ ences in the ion environments of those salts which have more than one crystal modification have been explored using potential energy calcula tions.