Chirality–helicity of cumulenes: A non‐scalar charge density derived perspective

Abstract

AbstractWe investigate the presence of helical character and chirality using a vector‐based charge density perspective instead of energetic or structural measures. The vector‐based perspective of the chemical bonding, constructed using the most preferred direction of charge density accumulation, finds the presence of induced symmetry‐breaking for α,ω‐disubstituted [4]cumulenes as the end groups are torsioned. The stress tensor trajectories Tσ(s) are used to provide the additional symmetry‐breaking required to quantify the degree and nature of the chirality and helical character. The S‐1,5‐dimethyl‐[4]cumulene contains a very low degree of chiral character but significant axiality(helicity) resulting in a weakly helical morphology of the corresponding Tσ(s). The (‐)S(‐), (+)S(‐) and (+)S(+) conformations of S‐1,5‐diamino‐[4]cumulene contain very significant degrees of both chirality and helical character resulting in helical morphology of the corresponding Tσ(s). We discuss the consequences for the Tσ(s) in locating chiral character in these molecules in future experiment investigations.