| Summary: | 碩士 === 國立中正大學 === 化學所 === 93 === In chapter one, the structures and energies of the noble-gas containing anions FNgO (Ng = Kr, Xe) have been calculated by high-level ab initio calculation. The FNgO were found to be deep energy minima at the singlet electronic state and their energies are significantly lower than those at the triplet state. High dissociation energy barriers to Ng + OF were also predicted. The unexpected stability of the FNgO was due to the dramatic ion-induced O=Ng bond formation. The calculated results suggested possible experimental identification of the anionic species and even some related “ionic compounds” under cryogenic conditions.
In chapter two of this thesis, high-level electronic structure calculation has been performed on the noble-gas molecules HNBArF, HNBKrF, and HNBXeF. The energetics of the two unimolecular dissociation pathways, (1) HNBNgF → HNB + Ng + F, and (2) HNBNgF → HNBF + Ng, were also calculated. The B–Ng bonds were calculated to be 1.7–2.5 and were found to be covalent in nature. Highly positive charges were assigned to H, B and Ng atoms and highly negative charges to N and F atoms. Both unimolecular dissociation pathways were found to have high energy barriers (>15 kcal/mol), and thus suggests that HNBNgF are dynamically stable species.
In chapter three, we have studied the Diels-Alder reactions of the furan derivatives－2,5-X2-furan, 3,4-X2-furan, and X4-furan (X = Me, Cl, Br, OMe) －with methyl vinyl ketone. The result indicated if the X groups are electron withdrawing, the reactions are more exothermic and have higher energy barriers. If the X groups are electron donating, the reactions are more endothermic, and the barriers are also higher, probably due to steric effects.
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