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High-resolution NMR spectra of fluorene and its derivatives-V 1H and 13C solvent and lanthanide-shift-reagent studies of fluorene-9-one

1980; Pergamon Press; Volume: 36; Issue: 1 Linguagem: Inglês

10.1016/0584-8539(80)80055-9

1873-3824

J. A. G. Drake, D. W. Jones,

Electron Spin Resonance Studies

LAOCOON analyses of 220 MHz 1H NMR high-resolution spectra of fluorene-9-one (I) in carbon disulphide and deuteriated chloroform solutions at 228–323 K yield closely similar ortho coupling constants. Concentration and temperature dependences of shifts suggest a loose, parallel head-to-head stacking. Eu(fod)3 shift reagent induces shifts in the same sequence, H(1) (closest to carbonyl) ⪢ H(4) ⪢ H(3) ⪢ H(2), as when the solvent is changed from carbon disulphide to chloroform, and a planar geometry for I is favoured in the Eu(fod)3-fluorene-9-one complex. Eu(fod)3-induced paramagnetic 13C shifts appear to involve appreciable contact contributions.