SOME 9-ARYLFLUORENES . RING-CURRENT EFFECTS ON NUCLEAR MAGNETIC RESONANCE SPECTRA CARBONIUM IONS AND 9-MESITYLFLUORENYL RADICAL

The nmr spectra of various 9-arylfluoren-9-oIs and derived carbonium ions are reported. 9-MesityIfluoren-9-ol exhibits three methyl resonance lines because of the magnetic anisotropy of the fluorene nucleus; similarly 9-durylfluoren-9-ol exhibits four methyl lines. These spectra are independent of temperature. 9-Chloro-9-mesitylfluorene has a temperature-dependent nmr spectrum in which the o-methyl lines are sharp at -10°dg and broad at 40°dg while the sharp line of the p-methyl is unaffected by temperature. This behavior is explained on the basis of the interconversion of mirror image forms of the chloride via reversible ionization. Other explanations involving either rotation of the 9-aryl substituent or simple equilibration with the 9-mesitylfluorenyl-9 cation are shown to be inconsistent with the experimental data. Similar behavior is observed for 9-chloro-9-durylfluorene. The nmr and optical spectra of various 9-arylfluorenyl-9 cations are reported and discussed briefly. The preparation and the optical and esr spectra of the stable, monomeric 9-mesitylfluorenyl radical are reported. © 1968, American Chemical Society. All rights reserved.