Activation of Ethylene by N‐Heterocyclic Carbene Coordinated Magnesium(I) Compounds

Reactions of a series of magnesium(I) compounds with ethylene, in the presence of an N‐heterocyclic carbene (NHC), have been explored. Treating [{( Mes Nacnac)Mg} 2 ] ( Mes Nacnac=[HC(MeCNMes) 2 ] − , Mes=mesityl) with an excess of ethylene in the presence of two equivalents of :C{(MeNCMe) 2 } (TMC) leads to the formal reductive coupling of ethylene, and formation of the 1,2‐dimagnesiobutane complex, [{( Mes Nacnac)(TMC)Mg} 2 (μ‐C 4 H 8 )]. In...