Structures of [(Amino)phenylsilyl]lithiums and Related Compounds in Solution and in the Solid State

The solution structures of [bis(diethylamino)phenylsilyl]lithium (1), [(diethylamino)diphenylsilyl]lithium (2), and [(diethylamino)phenylmethylsilyl]lithium (3) were investigated by 13C, 29Si, 7Li, and 15N NMR
spectroscopic experiments. The 29Si−7(6)Li coupling can be observed in each species at low temperature. The
coupling patterns indicate that these three species exist as monomers in THF. Using a 15N-enrichment technique,
the 29Si−15N couplings in 1 and 2 are observed. Next, the solid-state structures of [(diphenylamino)diphenylsilyl]lithium ((Ph2N)Ph2Si−X; X = Li) (4) and its fluoro (X = F) (16), stannyl (X = SnMe3) (17), and hydro (X
= H) (18) derivatives were revealed by crystallographic studies as well as by solid-state 29Si NMR experiments.
In the solid state, 4 exists as a monomer solvated with three THF molecules arising from the reaction solvent.
The electropositive substituent X, such as lithium, causes the elongation of the Si−C and Si−N bonds, reduction
of the sum of the C−Si−N (or C) angles, and a downfield shift of the 29Si resonances.