| This work focuses on several research projects that apply computational or spectroscopic techniques to study molecules of astrochemical relevance. Chapters 1 and 2 discuss computational projects relevant to carbon condensation and fullerene formation as proposed by the coalescence and annealing model. We find that alkynyl substitution of cyclobutadiene provides stabilization of the antiaromatic species which provides support of the proposed poly-alkynl cyclobutadiene intermediate. Further theoretical investigation reveals that the cyclization of the poly-alkynyl cyclobutadiene to form a para diradical via a Bergman cyclization may not be a viable step in fullerene formation and does not lead to the necessary 6-membered rings. This work calls into question the coalescence and annealing model of carbon condensation and fullerene formation.;Chapter 3 details a computational investigation of the decomposition of carbonyl diazide into diazirinone. This builds upon previous work refuting the original reports of diazirinone generation and our subsequent work synthesizing carbonyl diazide as a potential precursor. While incomplete, this work shows how the conformers of carbonyl diazide can interconvert and, by loss of nitrogen, can form 3nitreno-carbonylazide or azidoisocyanate. Higher-level, multi-reference calculations, such as SF-EOM-CCSD are likely needed to obtain a more definitive decomposition pathway that leads to diazirinone.;Chapters 4 and 5 describe the type of laboratory rotational spectroscopy typically used by radio astronomers to detect molecules in the interstellar medium. Chapter 4 describes the reconstruction and programming of the millimeter-wave spectrometer used to make these measurements. This instrument allowed us to complete an investigation of the rotational spectrum of pyridazine. We have observed several thousand transitions of pyridazine, its isotopomers, and its vibrationally-excited states. This work provides the spectroscopic data that are needed to search for this important 6-membered aromatic heterocycles in the interstellar medium by radioastronomy.;Chapter 6 describes an authentic use of computational chemistry to support the experiments completed in an undergraduate organic chemistry laboratory course. As a result of the curriculum redevelopment project, undergraduates are using WebMO and Gaussian to calculate conformers, transition states, reaction intermediates, molecular orbitals, and natural bond orbitals. |
