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Isolation and Structure of [(Fluorenone ⊙⊖){Na⊕(dme) 2 }] 2 —a Touchstone for Radical Contact Ion Pairs?
Author(s) -
Bock Hans,
Herrmann HansFriedrich,
Fenske Dieter,
Goesmann Helmut
Publication year - 1988
Publication title -
angewandte chemie international edition in english
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 0570-0833
DOI - 10.1002/anie.198810671
Subject(s) - delocalized electron , fluorenone , chemistry , radical ion , ion , ring (chemistry) , molecule , stoichiometry , sodium , crystallography , salt (chemistry) , metal , inorganic chemistry , alkali metal , photochemistry , organic chemistry , fluorene , polymer
Single crystals of a radical ion pair salt—the title compound —could be grown after stoichiometric reduction of fluorenone with sodium in aprotic solution under argon at –50°C. The structure determination reveals that a dimeric contact ion pair containing an Na 2 O 2 four‐membered ring is present and shows, for the first time, the bonding between radical anions and countercations: The solvated Na ⊕ ion is situated above the plane of the molecule and outside of the π CO plane. This finding further supports the assumption of a π spin delocalization from the radical anion to the metal cation, as derived from the positive ENDOR metal couplings of radical ion pairs in solution.