[(q5-C,H,)Re(NO)(PPh3)]+ and analogons unsaturated chiral complexes (see element symbols along the fingertips) can form two diastereomeric adducts with prochiral alkenes, aldehydes, and ketones. The ratio of these diastereomers is a measure of the chiral recognition, symbolized by the hands, of the reaction partners. The rhenium complex mentioned is depicted above the hands (Re: light gray, P: yellow, N: light blue, 0: dark blue, Ph, Cp: dark gray). The selectivity of alkene complexation can be analyzed (and predicted) by considering the sizes of the substituents a 4 on the alkene and correlating them with the steric conditions in the chiral complexes, which can be represented with three-dimensional bar graphs.