【作者】 任小元；

【导师】 刘子阳；

【作者基本信息】 浙江大学 ， 化学， 2005， 博士

【摘要】 本论文从实验和理论两方面系统地研究了以C₆₀为代表的富勒烯笼外、笼上和笼内的反应性质。 在质谱仪离子源内,研究了C₆₀与甲乙醚、甲丙醚、甲丁醚、乙醚、硅醚以及CS₂等形成的等离子体气氛的气相离子-分子反应,观察到C₆₀笼外衍生物的质谱峰。由三种甲醚Self-CI所产生的具有烯醇式或类烯醇式结构的[CH₂=OCH₃]⁺、[CH₂=O-CH₂CH₃]⁺、[CH₂=O-（CH₂）₂CH₃]⁺和[CH₂=O-（CH₂）₃CH₃]⁺离子与C₆₀具有很强的加合能力,形成加合离子,而形成的[M+H]⁺离子可以作为C₆₀的化学电离试剂离子使C₆₀质子化为[C₆₀H]⁺。硅醚Self-CI体系与C₆₀的反应也表现出与甲醚相似的反应特征,含有不饱和Si=O键的碎片的反应活性较强,但硅醚的[M+H]⁺不能使C₆₀质子化。对上述形成的加合离子进行了量子化学理论研究,HF和B3LYP/6-31G（d）计算表明,[C₆₀CH₂=OCH₃]⁺加合离子中,[CH₂=OCH₃]⁺以[3+2]环加成方式结合到C₆₀笼上的结构最为稳定。与甲基醚不同,加合物[C₆₀（CH₃）₂Si=OCH₃]⁺离子和[C₆₀（CH₃）₂SiOSi（CH₃）₃]⁺离子具有通过Si原子与C₆₀形成简单C-Siσ键合的结构,这与前体离子[（CH₃）₂Si=OCH₃]⁺和[（CH₃）₂SiOSi（CH₃）₃]⁺中Si原子上连接了较大的基团-CH₃有关。C₆₀与CS₂等离子体的反应形成了C₆₀的硫衍生物C₆₀S⁺离子,生成C₆₀S⁺离子有两种加合反应C₆₀+S⁺→C₆₀S⁺和C₆₀⁺S→C₆₀S⁺,前者的贡献是主要的。对加合离子C₆₀S⁺的理论计算表明,硫经6-6加合到C₆₀的结构具有最大的稳定性。以上气相离子-分子反应的实验结果以及对生成的加合离子的理论计算将为凝聚相下C₆₀化学性质的认识以及新型富勒烯衍生物的合成提供基础信息。 C₆₀笼上碳原子被杂原子取代后其性质发生很大改变。我们采用量子化学从头算和密度泛函方法研究了C₆₀笼上两个C原子被S取代生成的S杂C₅₈富勒烯C₅₈S的几何结构和电子性质,为对比起见,对C₅₈笼内包合S的结构S@C₅₈也进行了计算。结果表明,最稳定的C₅₈S为带有1个四员环和1个九员环的椭圆形开笼结构,九员环椭圆形开孔短轴和长轴的长度分别为3.199和4.256A,远比C₆₀中六员环的开孔大,为原子或小分子进入笼内提供了可能;S@C₅₈的最稳定构型为S原子位于C₅₈笼中偏离中心约0.667A处的结构,S离碳笼七元环附近的6-6键较近,最短更多还原

【Abstract】 The reactions properties of fullerenes that produce three kinds of derivates, i. e. exohedral, substitutional and endohedral doping fullerenes were studied both experimentally and theoretically.The gas-phase ion-molecule reactions of C₆₀ with methyl ethers, trimethylsilyl methyl ethers, hexamethyldisiloxane and CS₂ were studied in the ion source of a mass spectrometer. [CH₂O=CH₃]⁺, [CH₂=O-CH₂CH₃]⁺, [CH₂=O-（CH₂）₂CH₃]⁺ and [CH₂=O-（CH₂）₃CH₃]⁺ generated under the self-chemical-ionization （self-CI） conditions of alkylmethyl ethers can adduct with C₆₀ to produce the adduct ions [C₆₀C₂H₅O]⁺. These ethers are good protonating reagents to C₆₀ and [C₆₀H]⁺ are abundant in the resulted mass spectra. [C₆₀（CH₃）₂SiOCH3]⁺ and [C₆₀（CH₃）₂SiOSi（CH₃）₃]⁺, the reaction products of C₆₀ with dimethylsiloxymethyl ion [（CH₃）₂SiOCH₃]⁺ and the trimethylsiloxydimethylsilyl ion [（CH₃）₃SiOSi（CH₃）₂]⁺ were also observed as the major adduct ions. The ab initio and density functional theory molecular orbital calculations were carried out on all the possible structures of the adduct ions. The calculated results showed that the most stable structure among the possible isomers of [C₆₀C₂H₅O]⁺ is the 6-6 [3+2] cycloadduct. To [C₆₀（CH₃）₂SiOCH3]⁺ and [C₆₀（CH₃）₂SiOSi（CH₃）₃]⁺, the most stable structure is the σ_si adduct. According to experimental and theoretical results, the pathway for the formation of the adducts was presented. C₆₀S⁺ was synthesized through the gas-phase ion-molecule reaction of C₆₀ with the plasmas of carbon disulfide. Among the two reactions C₆₀+S⁺→C₆₀S⁺ and C₆₀⁺+S→C₆₀S⁺, the first one is the main reactions that produce C₆₀S⁺. Semi-empirical PM3-UHF and density functional B3LYP levels of theory with 6-31G（d） basis set calculations were performed on all the possible structures and electronic properties of the product. The results showed that the most stable structure among the possible isomers was the 6/6 closed derivative. These studies provided fundamental information on the understanding of the chemical properties of C₆₀ and the synthesis of novel fullerene derivatives.Substitutional doping makes many changes on the properties of C₆₀. Structural andelectronic properties of S-doped fullerene C58 were calculated systematically via Hartree-Fock self-consistent field and density functional B3LYP levels of theory with 6-31G（d） basis set. S@C58 was also calculated for comparing. The most stable C58S represents an open cage structure with a nine-member ring orifice that the longest and shortest axis lengths are 3.199 and 4.256 A respectively, far larger than that of C6o. Thus provides a large hole for atoms or small molecules to pass through into the cage. The most stable endohedral S@C5s has the S atom seated 0.667 A off the center of the C58 cage and near the 6-6 bond of the 7-member ring. The IR spectrum profile of S@C58 is similar to that of C58, while the IR spectrum profile of CssS is different from them. The most possible reaction sites of C5gS are on the C atoms and to S@C58 they are on the 7-member ring of the C58 cage. Compared with C60, both the abilities of electron accepting and donating of the S-doped hetrofullerenes are strengthened. Our results may aid in the design of experimental methods for controlling the nature of fullerene cages-for example, doping, opening, and reclosing them.The chemical properties of the internal cage of fullerenes were different from their external surface. The structural and electronic properties of atom endohedral doped fullerenes C@C6o and small neutral molecules H2, N2, CO endohedral doped C32, C36, C50 and C6o fullerenes were studied via Hartree-Fock self-consistent field （SCF） and density functional B3LYP levels of theory with the STO-3G, 6-31G（d） and 6-31G（d, p） basis sets. To C@C6o, the triplet structure with C on the center of the C60 cage was proved to be global minimum on the C@C6o molecular potential energy surface. Similar to N@C6o and P@C6o, there are no charge transfer between the encaged C atom and the fullerene cage. And no covalent bond is formed. Which is different from endohedral metallofullerens. In H2, N2, CO endohedral doped C32, C36, C50 and C60 fullerenes, the small molecules are seated near the center of the fullerene cages. The encaging of these molecules doesn’t change the geometries of the fullerenes much, while the bond lengths of CO and H2 are shortened and the N2 is lengthened. Almost no charge transfer happened between the encaged molecules and the fullerence cages. The inclusion reaction is endothermic. H2@Cn are more stable than N2@Cn and CO@Cn, and H2@C36, N2@C36, CO@C36 are the most reactive. Our studies suggestthat the internal cage of fullerene is more inert than its external surface. No charge transfer will happen when nonmetal atoms or small molecules are encaged into fullerene due to the weak electronegativity of the internal cage.The raw arc-discharging carbon soots exhibit high reactivity towards oxidants under basic condition. Water-soluble fullerenes C6o（OH）n and C7o（OH）n were synthesized directly from the raw soots in concentrated NaOH disusing the phase transfer catalyst. The laser desorption time-of-flight mass spectrum （LD-TOF MS） and FT-IR spectra were used to characterize the products, the probable reaction mechanism was discussed.A heatronic technique was used to synthesize metal carbides, metallofullerenes were synthesized by using Kra’tschmer arc burning of metal carbides and extracted from fullerene-containing soots by a novel reactive extraction method using alkali metals as reducing agents, the resulting extracts were free of empty fullerenes and M@Cgo, M@C82 and M2@Cso were selectively enriched. Electrospray-ionization （ESI） and Matrix-assisted laser-desorption-ionization time-of-flight mass spectrometry （MALDI-TOF） analysis were used to characterize the products. These studies present a new route to isolate metallofullerenes and an ESI-MS method to characterize them.更多还原