The first part of this thesis describes the development of carbonyl–olefin metathesis reactions utilizing hydrazine catalysts. The second chapter presents the challenges at hand for enabling ring–opening carbonyl olefin metathesis (ROCOM) on norbornene substrates. Through a combinatory computational and empirical approach, bicyclic hydrazine [2.2.2] with facile cycloreversion was identified and demonstrated to enable catalytic ROCOM on norbornenes. In the course of the study, hydrolysis, was identified as a barrier for efficient catalyst turn–over.The third chapter describes the development of ring opening metathesis polymerization (ROMP) of cyclopropenes, with hydrazonium initiators. Taking advantage of COM capability of bicyclic hydrazonium, cyclopropane monomers were polymerized by series of [3+2] cycloaddition and cycloreversion reactions. Detailed optimization along with reaction kinetics investigation unveiled that there is a positive correlation between monomer to initiator ratio and degree of polymerization. The fourth chapter describes the development of ring–closing COM (RCCOM) to generate polycyclic aromatic compounds (PAC) bearing Lewis basic functionalities, which can strongly inhibit conventional Lewis acid methodologies. Using 5 mol% catalyst loadings, a variety of PAC structures can be synthesized from biaryl alkenyl aldehydes, which themselves are readily prepared by cross-coupling reactions. In the second part of this thesis, the fifth chapter describes the discovery of cyclopropenimines’ (CPI) capability of rapid CO2 sequestration at room temperature. Decarboxylation temperature was demonstrated to be 60 °C in vacuo. CPI demonstrated remarkable oxidative and hydrolytic stability in the temperature range required for adsorption and regeneration. In the last chapter, another application of cyclopropenimine hydrochloride (CPI·HCl) as per– and polyfluoroalkyl substances (PFAS) adsorbent is discussed. The mechanism of PFAS removal was hypothesized to be through the formation of insoluble CPI–PFAS aggregates, which were subsequently removed via a conventional filter membrane. Fast removal kinetics (≤ 10 second) were observed on both legacy and emerging anionic PFAS. Factors with potential impact on CPI·HCl performance such as salt content, pH level and natural organic content were investigated. A demonstrative practical PFAS removal was illustrated through purification of PFAS spiked potable tap water from Cornell University, NY, USA.