Co-complexes of ortho-dilithiated thiophenol or 2-trimethylsilylthiophenol with lithiated TMEDA molecules:: synthesis, crystal structures and theoretical studies (TMEDA = N,N,N′,N′-tetramethylethylenediamine)

When an excess of (BuLi)-Bu-n was used in the ortho-dilithiation of thiophenol or 2-trimethylsilylthiophenol in the presence of TMEDA (TMEDA = N,N,N',M-tetramethylethylenediamine), deprotonation of TMEDA occurred and crystals of [Li-3{(2-S-C6H4)(CH2MeNCH2CH2NMe2)(TMEDA)}](2) (1) or [Li-4{(2-S-3-SiMe3-C6H3)(CH2MeNCH2CH2NMe2)(2)(TMEDA)}] (2) were obtained. Molecular orbital calculations on gas-phase 1 and 2 at the DFT B3LYP/6-31G(d) level reproduce the experimental structures fairly well. In spite of the short Li center dot center dot center dot Li distances, total electron density representations do not support the existence of Li center dot center dot center dot Li interactions.