NMR studies of dilithiostyrenes: aggregation, NMR parameters, and DFT calculations for (E)-1-Lithio-2-(o-lithiophenyl)-1-trimethylsilylethene.

The dilithio compound (E)-1-lithio-2-(o-lithiophenyl)-1-trimethylsilylethene (5) was synthesized from 2-trimethylsilylbenzo-[b]tellurophene (6) with lithium-6 and a detailed analysis of its H, Li, C, and Si NMR spectra showed 5 to form a dimer 5 in tetrahydrofuran and diethylether, while addition of tetramethylethylenediamine stabilizes a monomer 5 . A monomer-dimer equilibrium exists with K at 230 K = 1.25 and ΔG230o = -0.