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Solvation of indenyllithium and indenylpotassium studied by 13 C NMR spectroscopy
Author(s) -
Eliasson Bertil,
Lejon Tore,
Edlund Ulf,
Mueller Ronald L.,
Staley Stuart W.
Publication year - 1990
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.610030103
Subject(s) - chemistry , hexamethylphosphoramide , tetrahydrofuran , cryptand , solvation , ion , solvent , nuclear magnetic resonance spectroscopy , bromide , dimethyl sulfoxide , spectroscopy , inorganic chemistry , stereochemistry , organic chemistry , physics , quantum mechanics
Polarization of the π‐electron systems of indenyllithium (In − Li + ) and indenylpotassium (In − K + ), which is generally indicative of the degree and tightness of contact ion pairing, was investigated by 13 C NMR spectroscopy. The effect of changing solvent is about two thirds as great for In − K + as for In − Li + . The indenyl anion is more strongly polarized with Li + /dimethyl sulfoxide than with Li + /ammonia, whereas the reverse is observed for In − K + . Complexation of In − K + in tetrahydrofuran (THF) by cryptand(2,2,2) results in a π‐electron distribution identical with that of In − Li + in hexamethylphosphoramide, indicative of solvent‐ or agent‐separated ion pairs or free ions. Small but significant cation–anion interactions are observed for In − K + in hexamethylphosphoramide and for In − N + Me 4 in THF.