7Li Solid State NMR Study of a TMEDA Complex of Trimethylsilylcyclopentadienyllithium

Organolithium compounds are widely used as reagents in organic and organometallic synthesis. Since organolithium compounds usually form ag­ gregates in solution, their reactivity is drastically reduced. Therefore, donor reagents are added to the reaction mixture, which coordinate to the lithium atoms and thus break up the aggregates. The result is a considerable enhancement in reac­ tivity (and yield) [1, 2]. N,N,N',N'-Tetramethylethylenediamine (TMEDA) is one of the most common donors used. We studied structural and dynamic features of one of its adducts by means of 7Li solid state N M R spectroscopy. 7Li has a nu­ clear spin I = 3/2 and a quadrupole moment [3] of -40.1 • 10"3 m2. The quadrupole effect on the solid state N M R spectra is a sensitive probe and pro­ vides valuable structural information.