were synthesized by direct cycloaddition of quadricyclane with dimethylacetylenedicarboxylate and methyl propiolate, respectively (Figure ). Finally, for comparison of ROMP propagation rates (vide infra), exo-NB analogs of each TCN and TCND were synthesized following previously reported procedures. All monomers and intermediates were isolated non-chromatographically, and the key intermediates towards TCNs (1) and TCNDs (quadricyclane) were synthesized on the 16 g and 17 g scales, respectively. Notably, the melting temperatures for all but one (TCND-CO2Me) of the TCNs and TCNDs synthesized in this study were greater than their exo-NB analogs (from 10 °C to >150 °C higher), presumably due to their multicyclic, comparably rigid structures. In particular, all of the TCNs studied here have melting points >40 °C above room temperature, making them generally easy to handle and purify (crystallization). Ring-Opening Metathesis Polymerization (ROMP) of TCN and TCND Monomers. Each TCN and TCND described above (200 equiv) was exposed to G3 (1 equiv) in CDCl3 solvent to initiate ROMP. Reactions of TCNs were allowed to proceed for 15 minutes before quenching and precipitating twice from methanol, giving p(TCN)s in good yields (Table ). Size exclusion chromatography (SEC) revealed low dispersities (Đ) and number-average molar masses (Mn)