Reaction of energetic 11C(1D) atoms with ethylene by double-bond insertion

Energetic 11C(1D) atoms insert into the double bond of ethylene to yield [2-11C]allene, while the corresponding reaction with thermalized 11C(1D) atoms will not proceed; on the other hand, 11C(3p) atoms undergo both double bond and C–H insertion to yield [2-11C]- and [1-11C]allenes, respectively.