The central theme of our research is the discovery, development, and utilization of transition metal catalyzed reactions to overcome obstacles in traditional synthetic approaches. More specifically, we are interested in using metals to first elevate the reactivity of chemically inert reagents and then to exploit that heightened reactivity toward the construction of useful substrates. Ultimately, our hope is to provide synthetic chemists with a convenient and abbreviated approach to molecules rich with structural and/or functional diversity. Efforts are divided into catalyst discovery and optimization, mechanism elucidation, and application toward the construction of small molecules. An attractive method for the rapid construction of the heterocyclic core of numerous biologically active pharmacophores is the cycloaddition or rearrangement of unsaturated substrates. Unfortunately, such cycloadditions are often not thermally allowed and existing alternatives show poor functional group compatibility. Thus, considerable effort has been focused on developing transition metal catalysts that mediate such transformations. Ultimately, reactions that require prohibitively harsh conditions (high temperatures, high pressures) may become practical (room temperature, atmospheric pressures) when a transition metal catalyst is employed. We believe cycloadditions are particularly attractive because they: 1) represent an ideal, atom-efficient entry to ring systems, 2) require only simple, readily available starting materials, 3) are functional group tolerant, and, most importantly, 4) could provide a wide assortment of heterocycles. As such, we have built a research program centered around the development of a general Ni- and Fe-based cycloaddition catalyst system. In addition, the unsolved problem of CO2 activation continues to inspire us and has prompted another facet of our research program: metal-catalyzed CO2 activation reactions. As with our Ni-catalyzed cycloaddition chemistry, we seek to answer underlying, fundamental questions of what factors are important in reactions involving M-CO2 complexes.