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NMR Properties of Polylithiated C 60
Author(s) -
Bühl M.
Publication year - 2000
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/(sici)1521-3749(200002)626:2<332::aid-zaac332>3.0.co;2-q
Subject(s) - chemical shift , chemistry , atomic orbital , crystallography , endohedral fullerene , aromaticity , carbon 13 nmr , computational chemistry , molecule , stereochemistry , electron , physics , nuclear physics , organic chemistry
Endohedral, 13 C, 7 Li, and nucleus‐independent (NICS) chemical shifts are reported for selected Li n C 60 isomers (n = 6, 12, 18) at the GIAO (gauge‐including atomic orbitals)‐SCF/DZP//BP86/3–21G level. Li 6 C 60 closely resembles C 60 6– in terms of NMR criteria for aromaticity, as evidenced by an exceptionally high endohedral shielding. In contrast, nonaromaticity is indicated for Li 12 C 60 , based on a positive endohedral chemical shift. NICS and δ(endo) values very similar to those of Li 12 C 60 are obtained for Li 18 C 60 . According to population analysis, indeed the same number of electrons are transferred to the fullerene cage in both cases. Endohedral chemical shifts, accessible via 3 He NMR of the corresponding endohedral helium compounds, could thus be a valuable indicator for the extent of reduction of the C 60 molecule. Energetic estimates suggest that in the bulk, Li 12 C 60 should be unstable with respect to decomposition into Li 6 C 60 and lithium metal.