Theoretical studies on the ion-molecule reaction of CH3+ interacting with HNO,H2CNH,H2CO

甲基陽離子(methyl cation),CH3+,及HNO,H2CNH,H2CO的離子-分子縮合反 應(ion-molecule condensation reaction), 乃此等分子之氮原子或氧原 子的孤對電子(lone pair electrons)和CH3+形成縮合物(adduct)的過程, 是放熱反應(exothermic reaction) .其在298K時反應熱的負值定義為 MCA(methyl cation affinity). MP2=FULL/6-31G*的計算結果顯示H2CNH 氮原子最具MCA(116.56Kcal/mole), 其下依次為HNO氮原子 (88.77cal/ mole),H2CO氧原子(75.33kcal/mole), 而以HNO氧原子(62.60kcal/mole) 最弱.此等離子-分子縮合反應,Carbon Basicity及Nucleophilicity呈現 相同趨勢,因此H2CNH氮原子是最強之Nucleophile.經由反應形成之CH4 NO+,C2H6N+,C2H5O+系統,其Hartree- Fock及MP2位能曲面研究,一致顯示, 形成CH2NHCH3+之時的MCA足以克服其後氫1,2-shift 異構化現象的能量障 礙. 所有結構都是 RHF/6-31G*//RHF/6-31G* 及 RMP2=FULL/6-31G*// RMP2=FULL/6-31G*計算,並經頻率計算加以確認. 為求電子相關能量( electron correlation),更進一步做 RMP4SDTQ-FULL/6-31G*//RMP2= FULL/6-31G*單點計算 .Hartree-Fock ,MP2,MP4位能曲面屢有相異之處