Interstellar molecule CCCN may be formed by charge-stripping of [CCCN]- in the gas phase, and when energized, undergoes loss of C with partial carbon scrambling

Deprotonation of CH2=CHCN with HO- in the chemical ionization source of a VG ZAB 2HF mass spectrometer gives CH2=-CCN which fragments through [H- (HCCCN)] to give [CCCN](-). Similar reactions with (CH2CHCN)-C-13 and (CH2CHCN)-C-13 give [(CCCN)-C-13](-) and [(CCCN)-C-13](-). Collision induced dissociations of these anions, together with calculations at the CCSD(T)/aug-cc-pVDZHB3LYP/6-31+G(d) level of theory indicate that the anions do not rearrange under conditions used to charge strip them to their neutrals. A comparison of the charge reversal (-CR+) and neutralization/reionization (-NR+) mass spectra of [CCCN](-) indicate that neutral C3N species (formed by charge stripping of the anion) decompose by loss of C. Experimental studies with the C-13 labeled analogues indicate that the loss of C occurs subsequent to or accompanying partial carbon scrambling of the CCCN backbone. Theoretical studies suggest that this scrambling may occur during equilibration of CCCN and CCNC via a decomposing rhombic C3N intermediate.