NMR spectroscopy of organolithium compounds, part XIX1 reaction of (Z)-1,2-Bis(trimethylsilyl)-1-phenylethene with lithium: Dianion formation, schlenk dimerization, and 13C,6Li coupling in a benzyllithium system

Abstract Lithium reduction of ( Z )-1,2-bis(trimethylsilyl)-1-phenylethene ( 1 ) yields the dianion of the ( E )-isomer ( 3 ) and via Schlenk dimerization dilithium 1,4-diyl-1,4-diphenyl-1,2,3,4-tetrakis(trimethylsilyl)butane ( 4 ). The NMR parameters for both systems are reported and their solution structures are discussed. The formation of 4 is reversible and a unique feature of 4 is the scalar 1 J( 13 C. 6 Li ) spin-spin coupling constant of 2.7 Hz for the CLi bond, which is resolved even at room temperature.