A novel index for the description of molecular linearity.

To investigate the description of molecular shape, a heterogeneous data set of 200 compounds was designed. The compounds included many disparate molecular shapes, and a total of 64 descriptors was calculated including topological indices, surface areas, molecular volumes, measures of molecular dimensions, and ratios of moments of inertia. Cluster analysis on the variables indicated that there are four major categories of steric descriptors, those for molecular bulk, dimensions, and two clusters representing varying aspects of shape. To describe molecular shape more efficiently, a novel linearity index based upon ratios of moments of inertia and the molecular weight is proposed.