Chiral Induction from Allenes into Twisted 1,1,4,4‐Tetracyanobuta‐1,3‐dienes (TCBDs): Conformational Assignment by Circular Dichroism Spectroscopy

Conformational assignment: The mechanism of chiral induction in an optically pure 1,3‐diethynylallene, from the central chiral allene moiety into directly adjacent TCBD chromophores, was confirmed and clarified. Only one low‐energy conformer is found in calculations of the potential energy surface, which closely resembles the X‐ray crystal structure. Simulations of the CD spectrum by time‐dependent DFT showed a total agreement (see picture), in terms of position and sign, for all Cotton effects when compared to the experimental spectrum.