Nuclear Magnetic Resonance Facility (NMR) | Does the 1H NMR spectrum of Phenyl ring exhibit five distinct signals?

The X-ray structure of 1 indicates that the phenyl substituent is in a sterically congested environment, which could cause a relatively slow rate of rotation. In addition, the phenyl substituent is oriented roughly perpendicular to the newly formed chlorofluorenyl moiety, placing one of the ortho hydrogens in the magnetic shielding region of the neighboring indanone group. Indeed, the ¹H NMR spectrum of 1 in C₆D₆ using the 1D/2D TOCSY and COSY techniques revealed five distinct signals at δ 5.94 (ortho), 6.89 (meta), 7.15 (ortho), 7.17 (para), and 7.24 (meta) for the five hydrogens on the phenyl substituent, indicating a slow rate of rotation on the NMR time scale. In addition, the DEPT spectrum exhibited 21 signals for the 21 proton-bearing carbons, including five signals from the phenyl substituent and 16 signals from the rest of the molecule. The magnetic shielding was observed for one of the ortho hydrogens, which gave a significantly upfield shift signal at δ 5.94. Even at 80� C, this signal remained virtually unchanged and without significant line broadening. The perpendicular orientation of the phenyl substituent relative to the newly formed chlorofluorenyl moiety is also responsible for upfield shifting the proton signal of the neighboring hydrogen atom on the chlorofluorenyl moiety to δ 6.32 (C₆D₆). In the contour plot of the COSY spectrum, this signal was also used to locate the remaining three hydrogens on the same benzene ring at δ 6.60 (ortho), 6.90 (meta), and 7.37 (para).