Herein is reported an experimental and theoretical study of the circular dichroism properties of TRISPHAT (1) anion. ECD analysis of the [tetramethylammonium][Δ-1] salt confirms the absolute configuration assignment obtained through X-ray crystallographic analysis of the parent cinchonidium salt. The structure, infrared, and vibrational circular dichroism (VCD) spectra derived from density functional theory (DFT) calculations are compared with experimental data.

A [4](hetero)helicenium cation was resolved using the hexacoordinated phosphorus-containing binphat anion (see picture: N, blue; O, red; C, gray). Its absolute configuration was determined by vibrational circular dichroism spectroscopy. The barrier of interconversion of its enantiomers is higher than that of [6]helicene.