Automerizations and Isomerizations in Propynylidene (HCCCH), Propadienylidene (H₂CCC), and Cyclopropenylidene (<i>c</i>‐C₃H₂)

Abstract

Two previously undetected automerization processes occur among C3H2 isomers. On irradiation at λ = 313 nm, compounds 1a,b equilibrate via 3a,b; irradiation of compounds 2a,b at longer wavelengths (λ>444 nm) also leads to their interconversion, perhaps via a cyclopropyne intermediate or transition state.