Two informative and powerful indicators of molecular shape complexity are the fraction of sp hybridised carbons (Fsp3) and the fraction of stereogenic carbons (FCstereo). The Fsp3 index, as defined by Lovering et al., is a sizenormalised measure where the number of sp carbons is divided by the total number of carbons in a given organic molecule (eq. 1). Fsp3 = (number of sp