Abstracts of the Second International Conference on the Chemistry of the Alkali and Alkaline Earth Metals. Erlangen, Germany. September 17-20, 1997
ABSTRACT. Allenyl and propargyl type structures, respectively, of
the unsolvated lithium derivatives 1,3,3-triphenylpropyne (1-Li),
1-(2-methoxyphenyl)-3,3-diphenylpropyne (2-Li) and
9-[2-(2-methoxyphenyl)ethynyl]fluorene (3-Li), their bis-solvated
derivatives 1(2,3)-Li—2Et2O and 1(2,3)-Li—2H2O, as well as the structures
of the anions 1(2,3) were calculated by MNDO and PM3. The calculated
structures of 1-Li—2Et2O and 2-Li—2Et2O are compared with earlier
determined X-ray structures.
Spectroscopic investigations (UV-Vis and 13C nmr) reveal contact ion
character of 1(2,3)-Li in diethyl ether, while solvent separated ion pairs
are formed in THF. Furthermore, the regioselectivities observed in the
alkylation reactions of the different ion pairs of 1-Li and 2-Li were
determined and correlated with calculated electron density distributions.