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过渡金属氧化物与CH3Cl反应的基质隔离红外光谱及密度泛函理论计算研究

Matrix Isolation Infrared Spectroscopic and Theoretical Studies on the Reactions of Transitional Metal Mono- and Dioxides with Monochloromethane

作者: 专业:应用化学 导师:赵彦英 年度:2010 学位:硕士  院校: 浙江理工大学

Keywords

Matrix isolation, infrared spectroscopy, reaction intermediates, CH3Cl, transition metal oxides, density functional theoretical calculations

        本论文采用低温基质隔离红外光谱及密度泛函理论计算方法研究了一些简单过渡金属一氧化物(ScO,YO,NbO,TaO,TiO和ZrO )和二氧化物(NbO2,TaO2,TiO2和ZrO2)与CH3Cl的反应。金属氧化物分子是通过脉冲激光蒸发高价金属氧化物固体靶的方法制备。通过同位素(13CH3Cl, CD3Cl)取代实验结合密度泛函量子化学理论计算,归属并表征了反应中间体和产物,通过过渡态的结构和能量的势能面计算,得出了化学反应机理,进一步归纳总结了过渡金属氧化物与CH3Cl反应的规律。在低温Ar基质中,金属一氧化物MO与CH3Cl反应时,先自发形成MO(CH3Cl)络合物,若在不同波段光诱导下,络合物分子中的H或Cl会发生转移,然后进一步发生异构化反应。如在ScO,YO的实验中, MO(CH3Cl)络合物的异构化需要较高的活化能,在全光照下才能发生反应,异构化可沿两条路径进行,会形成两种异构化产物:CH2ClMOH,CH3OMCl。在NbO,TaO的实验中,络合物异构化的活化能较低,在可见光照射下,H原子会发生转移,生成CH2ClM(O)H。在TiO,ZrO的实验中,主要形成Cl转移的产物,其中在TiO中,在络合物在250 <λ< 500 nm紫外-可见光照下可转化成CH3Ti(O)Cl。而ZrO的实验中,反应较易进行,在沉积完退火之后,即可生成CH3Zr(O)Cl产物。金属一氧化物与CH3Cl反应归纳如下:金属二氧化物MO2(Nb,Ta,Ti,Zr)也都能与CH3Cl形成络合物MO2(CH3Cl),其结合能比相应的一氧化物要大。紫外光诱导下,在Nb,Ta实验中主要异构化为H转移的产物CH2ClM(O)OH。而在Ti, Zr实验中,络合物会异构化为Cl转移的产物CH3OM(O)Cl。金属二氧化物MO2与CH3Cl反应如下:
    The reactions of transitional metal monoxides (ScO, YO, NbO, TaO, TiO, and ZrO) and dioxides (NbO2, TaO2, TiO2 and ZrO2 ) with monochloromethane have been investigated by matrix isolation infrared spectroscopic and quantum chemical calculations. The metal monoxide and dioxide molecules were prepared by laser-evaporation of higher metal oxide targets. The reaction intermediates and products are identified by isotopic substitution and density functional theoretical calculations. The reaction mechanism and periodic trends are discussed.In the excess argon matrice, the initial step of the MO + CH3Cl is formation of MO(CH3Cl) complex. For the complex, one hydrogen or chlorine atom of CH3Cl transferred to form isomer upon different strong light irradiation. In the ScO and YO experiments, the MO(CH3Cl) complex required higher activation energy in isomerization, and so upon full UV light irradiation it isomized to two kinds of isomer CH2ClMOH, CH3OMCl. In the niobium and tantalum experiments, the activation energies of isomerization are much lower. Upon the visible light irradiation, the hydrogen atom of the MO(CH3Cl) complex converted to the M atom of MO to form CH2ClM(O)H molecule. In the Ti and Zr experiments, the chlorine atom of the complex transferred. Upon UV-visible light irradiation (250 <λ< 500 nm), TiO(CH3Cl) isomerized to the CH3Ti(O)Cl molecule. The CH3Zr(O)Cl molecule was observed on deposition and increased dramatically on annealing, which indicated that the formation of the CH3Zr(O)Cl molecule reqiured much lower activation energy.The reactions of metal monoxides with monochloromethane are summarized in Scheme1: The reactions of the metal dioxide molecules (MO2, M=Nb, Ta, Ti and Zr) with monochloromethane also produced the MO2(CH3Cl) complexes, whose binding energies are much larger than those of the corresponding MO(CH3Cl) complexes. The MO2(CH3Cl) complexes rearranged to the CH2ClM(O)OH(M=Nb and Ta) isomer upon UV light irradiation in the niobium and tantalum experiments, and on the same irradiation condition they rearranged to the CH3OM(O)Cl (M=Ti and Zr) isomer in the titanium and zirconic experiments.The reactions of metal dioxides with monochloromethane are summarized in Scheme2:
        

过渡金属氧化物与CH_3Cl反应的基质隔离红外光谱及密度泛函理论计算研究

中文摘要6-8
Abstract8-9
第一章 引言10-16
    1.1 CH_3Cl 的理化性质及其用途10
    1.2 CH_3Cl 与甲烷开发和利用10-11
    1.3 CH_3Cl 与大气环境11
    1.4 CH_3Cl 与金属及金属氧化物反应的研究进展11-15
    1.5 本论文的研究体系15-16
参考文献16-19
第二章 实验和理论计算方法19-23
    2.1 实验原理与仪器装置19-22
        2.1.1 实验原理简介19
        2.1.2 实验装置和实验方法19-22
    2.2 量子化学计算方法简介22-23
参考文献23-25
第三章 金属一氧化物MO 与CH_3Cl 的反应(M=Sc,Y,Nb,Ta,Ti 和Zr)25-57
    3.1 ScO 和YO 与CH_3Cl 的反应25-39
        3.1.1 红外光谱25-31
        3.1.2 计算结果31-34
        3.1.3 产物归属34-37
        3.1.4 反应机理37-39
    3.2 NbO 和TaO 与CH_3Cl 的反应39-47
        3.2.1 红外光谱39-42
        3.2.2 计算结果42-44
        3.2.3 产物归属44-45
        3.2.4 反应机理45-47
    3.3 TiO 和ZrO 与CH_3Cl 的反应47-55
        3.3.1 红外光谱47-50
        3.3.2 计算结果50-52
        3.3.3 产物归属52-53
        3.3.4 反应机理53-55
    3.4 金属一氧化物与CH_3Cl 反应规律总结55-57
参考文献57-60
第四章 金属二氧化物(MO_2)与CH_3Cl 反应(M=Nb,Ta,Ti,Zr)60-79
    4.1 NbO_2 和TaO_2 与CH_3Cl 的反应60-69
        4.1.1 红外光谱60-64
        4.1.2 计算结果64-65
        4.1.3 产物归属65-67
        4.1.4 反应机理67-69
    4.2 TiO_2 和Z1O_2 与CH_3Cl 的反应69-79
        4.2.1 红外光谱69-72
        4.2.2 计算结果72-75
        4.2.3 产物归属75-76
        4.2.4 反应机理76-78
        4.2.5 小结78-79
参考文献79-80
硕士期间发表的论文80-81
致谢81
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