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1.
Osuna S Swart M Campanera JM Poblet JM Solà M 《Journal of the American Chemical Society》2008,130(19):6206-6214
We report here for the first time a full comparison of the exohedral reactivity of a given fullerene and its parent trinitride template endohedral metallofullerene. In particular, we study the thermodynamics and kinetics for the Diels-Alder [4 + 2] cycloaddition between 1,3-butadiene and free D3h'-C78 fullerene and between butadiene and the corresponding endohedral D3h-Sc3N@C78 derivative. The reaction is studied for all nonequivalent bonds, in both the free and the endohedral fullerenes, at the BP86/TZP//BP86/DZP level. The change in exohedral reactivity and regioselectivity when a metal cluster is encapsulated inside the cage is profound. Consequently, the Diels-Alder reaction over the free fullerene and the endohedral derivative leads to totally different cycloadducts. This is caused by the metal nitride situated inside the fullerene cage that reduces the reactivity of the free fullerene and favors the reaction over different bonds. 相似文献
2.
It is known that silicon fullerenes cannot maintain perfect cage structures like carbon fullerenes. Previous density-functional theory calculations have shown that even with encapsulated species, nearly all endohedral silicon fullerenes exhibit highly puckered cage structures in comparison with their carbon counterparts. In this work, we present theoretical evidences that the tetrahedral fullerene cage Si(28) can be fully stabilized by encapsulating a tetrahedral metallic cluster (Al(4) or Ga(4)). To our knowledge, this is the first predicted endohedral silicon fullerene that can retain perfectly the same cage structure (without puckering) as the carbon fullerene counterpart (T(d)-C(28) fullerene). Density-functional theory calculations also suggest that the two endohedral metallosilicon fullerenes T(d)-M(4)@Si(28) (M=Al and Ga) can be chemically stable because both clusters have a large highest occupied molecular orbital-lowest unoccupied molecular orbital energy gap ( approximately 0.9 eV), strong spherical aromaticity (nucleus-independent chemical shift value of -36 and -44), and large binding and embedding energies. 相似文献
3.
Prof. Dr. Michio Yamada Prof. Dr. Takeshi Akasaka Prof. Dr. Shigeru Nagase 《Angewandte Chemie (International ed. in English)》2018,57(41):13394-13405
The awesome allotropy of carbon yields innumerable topologically possible cage structures of molecular carbon. This field is also related to endohedral metallofullerenes constructed by metal‐atom encapsulation. Stable and soluble empty fullerenes and endohedral metallofullerenes are available in pure form in macroscopic amounts from carbon arc production or other physical processes followed by extraction and subsequent chromatographic separation. However, many other unidentified fullerene species, which must be reactive and insoluble in their pristine forms, remain in soot. These “missing” species must have extremely small HOMO–LUMO gaps and may have unconventional cage structures. Recent progress in this field has demonstrated that reactive fullerenes can be salvaged by exohedral derivatization, which can stabilize the reactive carbon cages. This concept provides a means of preparing macroscopic amounts of unconventional fullerenes as their derivatives. 相似文献
4.
富勒烯合成化学研究进展 总被引:2,自引:0,他引:2
富勒烯是一类由12个五元环和若干六元环组成的笼状分子, 自20世纪80年代中期被发现以来就以其独特的结构和新奇的性质而成为科学界研究的热点, 25年来, 无论在基础研究还是在实际应用领域都有了长足的进步, 人们在发展富勒烯合成新方法和寻找富勒烯新结构方面做了大量的工作。本文对富勒烯的各种宏量合成方法进行了回顾, 并概述了迄今已发表的60余种富勒烯新结构,包括各种富勒烯空笼、内嵌富勒烯、富勒烯笼外修饰衍生物及氮杂富勒烯等结构。 相似文献
5.
The production, isolation, and spectroscopic characterization of a new Dy3N@C80 cluster fullerene that exhibits three isomers (1-3) is reported for the first time. In addition, the third isomer (3) forms a completely new C80 cage structure that has not been reported in any endohedral fullerenes so far. The isomeric structures of the Dy3N@C80 cluster fullerene were analyzed by studying HPLC retention behavior, laser desorption time-of-flight (LD-TOF) mass spectrometry, and UV-Vis-NIR and FTIR spectroscopy. The three isomers of Dy3N@C80 were all large band-gap (1.51, 1.33, and 1.31 eV for 1-3, respectively) materials, and could be classified as very stable fullerenes. According to results of FTIR spectroscopy, the Dy3N@C80 (I) (1) was assigned to the fullerene cage C80:7 (I(h)), whereas Dy3N@C80 (II) (2) had the cage structure of C80:6 (D(5h)). The most probable cage structure of Dy3N@C80 (III) (3) was proposed to be C80:1 (D(5d)). The significant differences between Dy3N@C80 and other reported M3N@C80 (M = Sc, Y, Gd, Tb, Ho, Er, Tm) cluster fullerenes are discussed in detail, and the strong influence of the metal on the nitride cluster fullerene formation is concluded. 相似文献
6.
Dunk PW Kaiser NK Mulet-Gas M Rodríguez-Fortea A Poblet JM Shinohara H Hendrickson CL Marshall AG Kroto HW 《Journal of the American Chemical Society》2012,134(22):9380-9389
The smallest fullerene to form in condensing carbon vapor has received considerable interest since the discovery of Buckminsterfullerene, C(60). Smaller fullerenes remain a largely unexplored class of all-carbon molecules that are predicted to exhibit fascinating properties due to the large degree of curvature and resulting highly pyramidalized carbon atoms in their structures. However, that curvature also renders the smallest fullerenes highly reactive, making them difficult to detect experimentally. Gas-phase attempts to investigate the smallest fullerene by stabilization through cage encapsulation of a metal have been hindered by the complexity of mass spectra that result from vaporization experiments which include non-fullerene clusters, empty cages, and metallofullerenes. We use high-resolution FT-ICR mass spectrometry to overcome that problem and investigate formation of the smallest fullerene by use of a pulsed laser vaporization cluster source. Here, we report that the C(28) fullerene stabilized by encapsulation with an appropriate metal forms directly from carbon vapor as the smallest fullerene under our conditions. Its stabilization is investigated, and we show that M@C(28) is formed by a bottom-up growth mechanism and is a precursor to larger metallofullerenes. In fact, it appears that the encapsulating metal species may catalyze or nucleate endohedral fullerene formation. 相似文献
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9.
Open-cage fullerene derivatives suitable for the encapsulation of a hydrogen molecule 总被引:3,自引:0,他引:3
Iwamatsu S Murata S Andoh Y Minoura M Kobayashi K Mizorogi N Nagase S 《The Journal of organic chemistry》2005,70(12):4820-4825
The encapsulation of molecular hydrogen into an open-cage fullerene having a 16-membered ring orifice has been investigated. It is achieved by the pressurization of H2 at 0.6-13.5 MPa to afford endohedral hydrogen complexes of open-cage fullerenes in up to 83% yield. The efficiency of encapsulation is dominantly dependent on both H2 pressure and temperature. Hydrogen molecules inside the C60 cage are observed in the range of -7.3 to -7.5 ppm in 1H NMR spectra, and the formations of hydrogen complexes are further confirmed by mass spectrometry. The trapped hydrogen is released by heating. The activation energy barriers for this process are determined to be 22-24 kcal/mol. The DSC measurement of the endohedral H2 complex reveals that the escape of H2 from the C60 cage corresponds to an exothermic process, indicating that encapsulated H2 destabilizes the fullerene. 相似文献
10.
Yang S Liu F Chen C Jiao M Wei T 《Chemical communications (Cambridge, England)》2011,47(43):11822-11839
Clusterfullerenes represent a novel branch of endohedral fullerenes, which are characterized by a robust fullerene cage with metal clusters encaged in its hollow. Since the discovery of nitride clusterfullerenes (NCFs) in 1999, the family of clusterfullerenes has been significantly expanded within the past decade, with new members including carbide clusterfullerenes (CCFs), hydrocarbide clusterfullerenes (HCCFs), oxide clusterfullerenes (OCFs), sulfide clusterfullerenes (SCFs), and carbonitride clusterfullerenes (CNCFs). We first present the classification of clusterfullerenes and list all the clusterfullerenes reported to date. For each type of clusterfullerenes, we review in detail their synthesis, separation, intriguing molecular structures and properties. For NCFs, as the first and most important clusterfullerenes, we point out the significance of their discovery and focus on their new synthesis and separation methods as well as the new advances. Finally the potential applications of clusterfullerenes are addressed. We conclude that clusterfullerenes appear to be the fastest growing family of endohedral fullerenes up to now, and emphasize the importance of exploring new structures and chemical functionalizations of clusterfullerenes. 相似文献
11.
Wang TS Feng L Wu JY Xu W Xiang JF Tan K Ma YH Zheng JP Jiang L Lu X Shu CY Wang CR 《Journal of the American Chemical Society》2010,132(46):16362-16364
The endohedral fullerene Sc(3)NC@C(80)-I(h) has been synthesized and characterized; it has an unprecedented planar quinary cluster in a fullerene cage. It is also the first chemical compound in which the presence of an unprecedented (NC)(3-) trianion has been disclosed. The fascinating intramolecular dynamics in Sc(3)NC@C(80)-I(h) enables the whole molecule to display high polarity and promising ferroelectricity. This finding inspires the possibility that such a planar quinary cluster may be useful in constructing many other endohedral fullerenes. 相似文献
12.
The most abundant fullerenes, C60 and C70, and all the pure carbon fullerenes larger than C70, follow the isolated‐pentagon rule (IPR). Non‐IPR fullerenes containing adjacent pentagons (APs) have been stabilized experimentally in cases where, according to Euler’s theorem, it is topologically impossible to isolate all the pentagons from each other. Surprisingly, recent experiments have shown that a few endohedral fullerenes, for which IPR structures are possible, are stabilized in non‐IPR cages. We show that, apart from strain, the physical property that governs the relative stabilities of fullerenes is the charge distribution in the cage. This charge distribution is controlled by the number and location of APs and pyrene motifs. We show that, when these motifs are uniformly distributed in the cage and well‐separated from one other, stabilization of non‐IPR endohedral and exohedral derivatives, as well as pure carbon fullerene anions and cations, is the rule, rather than the exception. This suggests that non‐IPR derivatives might be even more common than IPR ones. 相似文献
13.
Runnan Guan Muqing Chen Fei Jin Shangfeng Yang 《Angewandte Chemie (International ed. in English)》2020,59(3):1048-1073
According to the isolated pentagon rule (IPR), for stable fullerenes, the 12 pentagons should be isolated from one another by hexagons, otherwise the fused pentagons will result in an increase in the local steric strain of the fullerene cage. However, the successful isolation of more than 100 endohedral and exohedral fullerenes containing fused pentagons over the past 20 years has shown that strain release of fused pentagons in fullerene cages is feasible. Herein, we present a general overview on fused‐pentagon‐containing (i.e. non‐IPR) fullerenes through an exhaustive review of all the types of fused‐pentagon‐containing fullerenes reported to date. We clarify how the strain of fused pentagons can be released in different manners, and provide an in‐depth understanding of the role of fused pentagons in the stability, electronic properties, and chemical reactivity of fullerene cages. 相似文献
14.
Zuo T Xu L Beavers CM Olmstead MM Fu W Crawford TD Balch AL Dorn HC 《Journal of the American Chemical Society》2008,130(39):12992-12997
Y2@C79N and Tb2@C79N have been prepared by conducting the Kratschmer-Huffman electric-arc process under 20 Torr of N2 and 280 Torr of He with metal oxide-doped graphite rods. These new heterofullerenes were separated from the resulting mixture of empty cage fullerenes and endohedral fullerenes by chemical separation and a two-stage chromatographic process. Crystallographic data for Tb2@C79N x Ni(OEP) x 2 C6H6 demonstrate the presence of an 80-atom cage with idealized I(h) symmetry and two, widely separated Tb atoms inside with a Tb-Tb separation of 3.9020(10) A for the major terbium sites. The EPR spectrum of the odd-electron Y2@C79N indicates that the spin density largely resides on the two equivalent yttrium ions. Computational studies on Y2@C79N suggest that the nitrogen atom resides at a 665 ring junction in the equator on the fullerene cage and that the unpaired electron is localized in a bonding orbital between the two yttrium ions of this stable radical. Thus, the Tb-Tb bond length of the single-electron bond is an exceedingly long metal-metal bond. 相似文献
15.
Fullerene molecules have nano-scale cavities in which various metal or metal clusters of different sizes can be embedded to form metallofullerenes with unique core-shell structures. The physical and chemical properties of metallofullerenes can be modified through the interaction between the encapsulated metals and the fullerene cages. As such, the investigation of metallofullerenes with novel structures has been a principal research focus in the field of fullerenes. In this study, we investigated the size matching effect between encapsulated clusters and fullerene cages for the endohedral metal carbonitride clusterfullerenes in order to discover new metallofullerenes. The stability and electronic structure of the metallofullerenes formed by encapsulating M3NC clusters (M = Y, La, Gd) into D2(186)-C96 and D2(35)-C88 fullerenes were studied using quantum chemical calculations. It was found that the fullerene cages formed stable structures by accepting six electrons transferred from the encapsulated clusters. The change in configuration of the encapsulated clusters was clarified by a comparison with the corresponding M3N@C2n metal nitride clusterfullerenes; the size matching effect between M3NC cluster and fullerene cage was elucidated on the basis of the calculated results and previous studies on Sc3NC@Ih(7)-C80. For the D2(186)-C96 fullerene, the Gd3NC cluster was found to have smaller changes in the configuration as compared with the La3NC cluster, proving that Gd3NC is more suitable than La3NC for encapsulation in the D2(186)-C96 fullerene cage. In addition, it was determined that the La3NC cluster requires a large structural change to maintain its planar configuration. For the D2(35)-C88 fullerene cage, the Y3NC cluster is more suitable than Gd3NC for encapsulation owing to the smaller size of the Y3NC cluster. The spatial distribution of the highest occupied and lowest unoccupied molecular orbitals (HOMO and LUMO) of Gd3NC@D2(186)-C96 were found to be similar to those of Gd3N@D2(186)-C96. However, a unique endohedral cluster-based occupied molecular orbital was found for Gd3NC@D2(186)-C96. This orbital is derived from the interaction between the NC unit and the Gd atoms. The spatial distribution of the HOMO of Y3NC@D2(35)-C88 is similar to that of Y3N@D2(35)-C88, while the LUMO of Y3NC@D2(35)-C88 has a much larger contribution from the endohedral cluster as compared to Y3N@D2(35)-C88. Thus, the addition of a carbon atom in the cluster has a remarkable impact on the electronic structure of the metallofullerenes. With respect to structural characteristics, we found that the three fullerene cages, D2(186)-C96, D2(35)-C88, and Ih(7)-C80, have a uniform distribution of five-membered carbon atom rings; these fullerenes can be greatly stabilized in the form of C2n6- anions. However, the formation mechanism of fullerenes and metallofullerenes, at present, is poorly understood. Based on the structural analysis, we propose a direct mechanism for the formation of fullerenes without the Stone-Wales isomerization, i.e., the rearrangement of five-membered rings through the addition of carbon atoms and the transformation into larger carbon cages while maintaining stable structural units. 相似文献
16.
为了研究富勒烯金属包合物Be@C74的结构和电子性质,本文采用密度泛函理论B3LYP方法优化了Be@C74的结构,计算了它的势能面、LUMO-HOMO、电子亲和势、电子化能以及Mulliken集居数。结果表明:Be原子位于C74笼中心并且近似保持基态的电子构型;Be原子和C74笼之间是相互排斥作用;Be原子包入C74笼中心后,C74笼只有微小的变形;包合物Be@C74笼的给予和得到电力的能力与C74空笼几乎不变;Be与C74笼之间只有微小的杂化。 相似文献
17.
Structural interconnections and the role of heptagonal rings in endohedral trimetallic nitride template fullerenes
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Recent experiments indicate that fullerene isomers outside the classical definition can also encapsulate metallic atoms or clusters to form endohedral metallofullerenes. Our systematic study using DFT calculations, suggests that many heptagon‐including nonclassical trimetallic nitride template fullerenes are similar in stability to their classical counterparts, and that conversion between low‐energy nonclassical and classical parent cages via Endo–Kroto insertion/extrusion of C2 units and Stone–Wales isomerization may facilitate the formation of endohedral trimetallic nitride fullerenes. Close structural connections are found between favored isomers of trimetallic nitride template fullerenes from C78 to C82. It appears that the lower symmetry and local deformations associated with introduction of a heptagonal ring favor encapsulation of intrinsically less symmetrical mixed metal nitride clusters. © 2016 Wiley Periodicals, Inc. 相似文献
18.
Sally Bloodworth Gabriela Sitinova Shamim Alom Sara Vidal George R. Bacanu Stuart J. Elliott Mark E. Light Julie M. Herniman G. John Langley Malcolm H. Levitt Richard J. Whitby 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(15):5092-5097
The endohedral fullerene CH4@C60, in which each C60 fullerene cage encapsulates a single methane molecule, has been synthesized for the first time. Methane is the first organic molecule, as well as the largest, to have been encapsulated in C60 to date. The key orifice contraction step, a photochemical desulfinylation of an open fullerene, was completed, even though it is inhibited by the endohedral molecule. The crystal structure of the nickel(II) octaethylporphyrin/ benzene solvate shows no significant distortion of the carbon cage, relative to the C60 analogue, and shows the methane hydrogens as a shell of electron density around the central carbon, indicative of the quantum nature of the methane. The 1H spin‐lattice relaxation times (T1) for endohedral methane are similar to those observed in the gas phase, indicating that methane is freely rotating inside the C60 cage. The synthesis of CH4@C60 opens a route to endofullerenes incorporating large guest molecules and atoms. 相似文献
19.
The family of endohedral fullerenes was significantly enlarged within the past six years by the clusterfullerenes containing structures like the M(2)C(2) carbides and the M(3)N nitrides. While the carbide clusters are generated under the standard arc burning conditions according to the stabilisation energy the nitride clusterfullerene type is formed by varying the composition of the cooling gas atmosphere in the arc burning process. The special situation in nitride clusterfullerene synthesis is described in detail and the optimum conditions for the production of nitride clusterfullerenes as the main product in fullerene synthesis are discussed. A review of new nitride clusterfullerenes reported recently is given summarizing the structures, properties and the stability of metal nitride clusterfullerenes. It is shown that all cages with even carbon atoms of C(68) and beyond are available as endohedral nitride clusterstructures. Furthermore the nitride clusterfullerenes are that class of endohedral fullerenes forming the largest number of non-IPR structures. Finally the prospects of this evolving field are briefly discussed taking the superior stability of these endohedral clusterfullerenes into account. 相似文献
20.
The application of in situ ESR–UV/VIS/NIR spectroelectrochemistry to the highly purified C82:3 fullerene isomer with C2 symmetry made the detailed characterization of the radical structures formed by electrochemical generation possible. This first comprehensive spectroelectrochemical study of the stable radical anion and cation of an empty cage higher fullerene in acid-free organic electrolyte is a contribution to the general understanding of charged states at endohedral fullerenes. 相似文献