Vinyllithium

Vinyllithium is an organolithium compound with the formula LiC2H3. A colorless or white solid, it is encountered mainly as a solution in tetrahydrofuran (THF). It is a reagent in synthesis of organic compounds.
Preparation and structure.
Solutions of vinyllithium are prepared by lithium-halogen exchange reactions. A halide-free route entails reaction of tetravinyltin with butyllithium:
The reaction of ethylene and lithium affords vinyl lithium and lithium hydride, together with other organolithium compounds, 
Like most organolithium compounds, vinyllithium crystallizes from THF as a cluster compound as a cubane-type cluster.
Reactions.
Vinyllithium is used to install vinyl groups on metal-based reagents, being a precursor to vinylsilanes, vinylcuprates, and vinylstannanes. It adds to ketones compounds to give allylic alcohols. Vinylmagnesium bromide is often used in place of vinyllithium.