Fluorenone Monomer Dianion Studied by 1H and 13C NMR and Charge Density Distribution

Article abstract of DOI:10.1246/bcsj.60.2751

The diamagnetic monomer dianion of fluorenone was prepared from 1,2-dimethoxyethane solution of neutral molecule in contact with excess sodium metal at -5 deg C for 5 days and its 1H and 13C NMR spectra were measured.The possibility that pinacolate-type dimer dianion occurs in an equilibrium system was ruled out from reactivity with oxygen, water, deuterium oxide, and reducible aromatics in addition to the analysis of NMR spectra.The charge density distribution of neutral and dianion molecules was estimated by MO calculations.Comparison between experimental and theoretical 13 C shifts suggested a strong interaction of sodium ions with carbonyl group.It is presumed that an anormalous diamagnetic ring current in 14?-peripheral structure is responsible for poor correlation between theoretical and observed 1H shifts.