Theoretical prediction of the new noble-gas containinganions FNgO− and molecules HNBNgF (Ng = Ar, Kr, Xe)and theoretical study of the Diels-Alder reactions of furanderivatives with methyl vinyl ketone

• Main Authors: Chun-Hao Mou, 牟君浩
• Other Authors: Wei-Ping Hu
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/98187397142258064336

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.