The prediction of the circular dichroism of the benzene chromophore: TDDFT calculations and sector rules

The CD spectra of the series PhCH(Me)R, with R 5 Et (1), nPr (2), iPr (3), and tBu (4), are reported (1–3 for the first time) at room temperature in the 185–280 nm range and at 183 K. These purely hydrocarbon compounds represent the simplest chiral systems containing the phenyl chromophore and exhibit Cotton effects exclusively allied with the benzene transitions. The bands in 1La and 1Lb regions were checked against the available sector rules, with discordant outcomes. Time-dependent density-functional theory calculations, with various functionals and basis sets tested, correctly reproduced the prominent CD bands observed for 1–4.