Conformational Analysis of (+-)(1,1'-Biindene)-3,3'-done,2,2',3,3'-Tetrahydro-(1,1'-binaphthalene)-4,4'(1H,1'H)-dione,and (1,1'-Bibenzosuberene)-5,5-dione

摘要

The dipole moments of (+-0-(1,1'-biindene)-3,3-dione 1, (+-)-2,2',3,3'-tetrahydro-(1,1'-binaphthalene)-4,4'(1H,1'H)-dione 2,and (+-)-(1,1'-bibenzosuberene)-5,5-dione 3 in carbon tetrachloride and benzene were measured at 25 deg C,1 exists predominantly in the gauche conformation,whilst 2 and 3 favor the trans form.;The experimentally derived values of the energy difference between the gauche and trans rotamers and the gauche/trans population qutient were compared with values predicted by molecular-orbital calculations.The crystal and molecular structures of 2 and 3 were determined by single-crystal X-ray diffraction methos.Both compounds exist in the trans conformation in the solid-state.Dynamic ~1H NMR was employed to 3 in order to determine the activation parameters for the barriers to rotation in solution.