STRUCTURAL STUDIES OF FLUORENYLLITHIUM COMPLEXES USING LI-7 SOLID-STATE NMR-SPECTROSCOPY

The effect on the sold-state Li-7 chemical shifts and quadrupolar coup ling constants of different locations of the lithium cation relative t o the carbanion framework of delocalized carbanions was investigated. When the lithium cation is situated above the conjugated system, the c hemical shift is about -7 ppm as expected, and around -2 ppm otherwise . The quadrupolar coupling constant is very sensitive to changes in th e lithium cation position and to changes in coordination, The value va ries between 27 and 262 kHz. A combination of chemical shifts and quad rupolar coupling constants is necessary to retrieve the correct struct ural information.