Fig. 1: Stacked variable temperature 1H NMR spectra of 1U in toluene-d8 with resonances corresponding to the phenyl protons of the SiPh3 groups labeled.

The temperature range is from 300 K (lower, dark green) to 350 K (upper, light green). The COT ring CAr-H ring resonances for 1U are outside the displayed range, see SI for NMR spectra of all 1An. * corresponds to the toluene CH3 resonance.