Trivinyl compounds of Group V elements have been prepared by the reaction between vinyl Grignard reagent and the appropriate trihalide. Some physical properties of these trivinyl derivatives are reported, and several new addition compqunds of the type [(CH,: CH) aRMv] X are described. The ability to form" onium" type adducts decreases in passing from trivinylphosphine to triv~ nylblsmuth. Trivinylarsine and-stibine form complex compounds [ ...