Theoretical Study of Intra-molecular Hydrogen Transfer of Formyl radical and Its complexes

• Main Authors: Hsiao-Chuan Yang, 楊小娟
• Other Authors: Jia-Jen Ho
• Format: Others
• Language: zh-TW
• Published: 1999
• Online Access: http://ndltd.ncl.edu.tw/handle/00814124819487045991

碩士 === 國立臺灣師範大學 === 化學研究所 === 87 === Abstract This dissertation deals with the calculation of intramolecular hydrogen transfer of formyl radical and its derivative complexes by ab initio and DFT methods. Each local minimum and its corresponding TS are fully optimized with 6-311G** and 6-311++G** basis sets at the levels of HF、MP2 and B3LYP. Relative energies of species are finally evaluated at B3LYP、MP2 or G2 theory. There are five sections rendered here. Section 1:　First of all, we study the intramolecular hydrogen transfer of the formyl radical (HCO), which is a trial and used as a comparison to the data in the literature. Results indicate that structure of HCO calculated by DFT method with B3LYP/6-311++G** level is very close to the experimental values. The result is RC-O=1.174 A、RC-H=1.125 A and ∠HCO=124.5°. With respect to previous studies, DFT method takes shorter time in calculating and more accurate in the geometry structure. However in other levels, the calculated barrier is about 64~69 kcal/mol for the intramolecular hydrogen transfer. The binding energy of H-CO bond calculated by G2 method including BSSE correction is —13.72 kcal/mol. Section 2:　Intramolecular hydrogen transfer of complex of HC(O)O2 is studied in this section. In ground state, formylperoxy radical is found to have two isomers, among which are Z and E forms. There are three different product channels in performing intramolecular hydrogen transfer onto the two isomers. The first product is like a carbene structure having higher energy than the reactants (HCO+O2) by 40 kcal/mol. The second channel produces HO2+CO with activation energy of 0.201 kcal/mol at 298 K, B3LYP/6-311++G** level. The activation energy of the third product channel (OH+CO2) is 9.5 kcal/mol. We concluded that the barrier of intramolecular hydrogen transfer is affected by the strain of the transition structure. Section 3:　We studied the intramolecular hydrogen transfer of the Nitrosylformate complex HC(O)NO2. There were four paths of hydrogen transfer discussed, which include the transition structure of 3-, 4-, or 5- member ring. It is found that the barrier of 3- member ring is the highest and that of 4- member ring is almost equal to the barrier of 5- member ring. Because of different structure and distance between the original atom (C) and the target atom (O), 5-member ring has a higher energy barrier. The strain of the transition state surely dominates the energy barrier of the hydrogen transfer. Section 4:　 The intramolecular hydrogen transfer of HC(O)NO3 complex is also studied. The binding energy of HCO and NO3 is quite high. The resultant product (HNO3) is also observed by experiment. Section 5: Finally, we focused our study on the intramolecular hydrogen transfer of HC(O)O3 complex. There are three isomers of HC(O)O3. The first isomer (complex I) has no barrier for the hydrogen transfer. The splitting products of the complex, II and III, after hydrogen transfer are CO+HOOO and CO+HO3, respectively, their energy differences are quite large.