The global minimum structure of SiC3: The controversy continues

The linear triplet structure of SiC3 (with terminal Si) has been investigated using coupled cluster methods, including a perturbative treatment of triple excitations, and Dunning’s correlation-consistent polarized core-valence quadrupole zeta basis set (CCSD(T)/cc-pCVQZ). Based on the demonstrated convergence with respect to correlation and the large basis set employed, this triplet isomer appears to be energetically less stable than the two ring isomers, which have either a C–C (2s) or a Si–C (3s) transannular bond, by 7.5 and 1.3 kcal /mole, respectively.