We have found only a limited number of HCN-derived polymers and molecules to be thermodynamically downhill relative to 5. For example, and in agreement with previous theoretical studies, the formation of 7 from 5 is thermodynamically allowed. The linear polymer 21 is another example that could feasibly form from 5. Structures 19 and 33 are predicted to be the most stable polymers out of those considered, with only the molecule 7 being more stable. Formation of 19 and 33 from 5 is predicted to be spontaneous by -6.0 and -6.3 kcal/mol HCN, respectively.