The energetics of the reaction C 2+ 2 --→ 2C + , discussed later in Section 3.2.5, were computed at CCSD(T)/aug-cc-pVTZ using the ORCA 5 software. The geometries of C 2+ 2 were optimized for the singlet, triplet, and quintet multiplicities, with the triplet being the lowest energy state. For the carbon monocation, doublet and quadruplet states were computed, with the doublet found to be the lowest in energy. All the geometries and energies are given in the ESI.