采用了从头算分子轨道理论(MP2,非限性的二级微扰理论)和密度泛涵理论(B3LYP),分别在6-31G(d,p),6-311G(d,p),6-311+G(d,p),6-311G(2d,p),和6-311+G(2df,2p)基组上优化CH3-nFnO2-Li+(n=0～3)的几何结构,计算出了相关的NBO电荷分布和锂离子相对于自由基CH3-nFnO2的亲和能.并在同一水平上计算了自由基CH3-nFnO2和络合物CH3-nFnO2-Li+的相关伸缩振动频率.CH3-nFnO2在UB3LYP/6-311G(d,p)得到的振动频率与实验值符合得很好.根据相关的文献报道,我们运用从头算分子轨道理论和密度泛涵理论计算出的锂离子相对于CH3-nFnO2的亲和能都能够表明络合物CH3-nFnO2-Li+在气态下能以一种稳定的物种形态被离子附着质谱检测.
The equilibrium geometries, harmonic vibrational frequencies, natural bond orbital (NBO) charge distributions, and the affinity energies of Li+ attachment to CH3-nFnO2(n = 0 ～ 3)have been investigated using ab initio molecular orbital theory and density functional theory (DFT).The structures were determined using unrestricted second order Mφller-Plesset(UMP2) and unrestricted Beck's three-parameter Lee-Yang-Parr(UB3LYP) theories in conjunction with 6-31G (d, p),6-311G (d, p), 6-311+G (d, p), 6-311G (2d, p) and 6-311+G (2df, 2p) basis sets, and the stretching vibrational frequencies were investigated for CH3-nFnO2 and CH3-nFnO2-Li+, using optimized geometries at the same levels. The calculated vibrational frequencies of radicals at UB3LYP/6-311G(d, p) levels were consistent well with the experimental data. The affinity energies of Li+attachment to CH3-nFnO2(n = 0 ～ 3), calculated by DFT and ab intio are all large which suggest that CH3-nFnO2-Li+ complexes could be possibly detected as stable species in gas phase by ion attachment mass spectrometry.
参考文献
| [1] | Schiff H I,Ann N Y.Mass spectrometry of gases subjected to electrical discharge[J].Aca.Sci.,1957,67:518-529. |
| [2] | Cuthbert J.Mass spectrometric sampling and detection of intermediates in gaseous reactions[J].Adv.Mass.Spectrom.,1966,3:821-839. |
| [3] | Foner S N.Mass spectrometry of free radicals[J].Adv.Atom.Mol.Phys.,1966,2:385-461. |
| [4] | Fujii T.A novel method for detection of radical species in the gas phase:uage of Li+ ion attachment to chemical species[J].Chem.Phys.Lett.,1992,191(1-2):162-168. |
| [5] | Fujii T.Alkali-metal ion/molecule association reactions and their application to mass spectrometry[J].Mass Spectrom.Rev.,2000,19(3):111-138. |
| [6] | Bentley T.Theoretical study of lithium cation interactions with hydrocarbon radicals[J].Chem.Phys.Lett.,1992,200(5):518-523. |
| [7] | Felice G,Vittorio V.Complexes of lithium cation with nitrogen trifluoride:a computational investigation on the structure and stability of Li+-NF3 isomers[J].J.Mol.Struct.(THEOCHEM).,2001,574:185-193. |
| [8] | Sablier M,Fujii T.Mass spectrometry of free radicals[J].Chem.Rev.,2002,9:2855-2923. |
| [9] | Ahsen S,Willner H.Fluorocarbon oxy and peroxy radicals[J].J.Fluorine.Chem.,2004,125:1057-1070. |
| [10] | Wallington T J,Dagaut P,Kurylo M.UV absorption cross sections and reaction kinetics and mechanisms for peroxy radicals in the gas phase[J].Chem.Rev.,1992,92(4):667-710. |
| [11] | Timothy J W,James C B.Spectroscopic,kinetic,and mechanistic study of CH2FO2 radicals in the gas phase at 298 K[J].J.Phys.Chem.,1992,96:1241-1246. |
| [12] | El-taher S,El-azhary A A.Theoretical investigation of the structures and properties of fluoromethyl peroxyl radicals[J].Int.J.Quant.Chem.,2004,98:502-514. |
| [13] | Nandi S,Blanksby S J,et al.Polaried infrared absorption spectrum of matrix-isolated methylperoxyl radicals[J].J.Phys.Chem.A.,2002,106(33):7547-7556. |
| [14] | Liu L,Davis SR.Matrix-isolation spectroscopic study of tetrafluoroethylene oxidation[J].J.Phys.Chem.,1992,96(24):9719-9724. |
| [15] | Frisch M J,Trucks G W,Schlegel H B,et al.Gaussian O3[S].Pittsburgh,pA,2003. |
| [16] | Fujii T,Tokiwa H,Ichikawa H.Li+ affinity of C2H3 and C2H5 radicals,ab initio characterization of Li+-radical complexes[J].J.Mol.Struct.(THEOCHEM).,1995,339:209-217. |
| [17] | Fujii T,Yashiro M,Tokiwa H.Proton and Li+ cation interactions with H2O3 and H2O/O2:ab initio molecular orbital study[J].J.Am.Chem.Soc.,1997,119:12280-12284. |
| [18] | Burk P,Koppel I A,Kopper I,et al.Revised and expanded scale of gas-phase lithium cation basicities.an experimental and theoretical atudy[J].J.Phys.Chem.A,2000,104:2824-2833. |
- 下载量()
- 访问量()
- 您的评分：
-
10%
-
20%
-
30%
-
40%
-
50%