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1.
Prof. Bing Yu Dr. Wangqiang Shen Le Yang Yangchun Liu Dr. Changwang Pan Prof. Hailin Cong Prof. Peng Jin Prof. Xing Lu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(11):2464-2469
Chemical modification of endohedral metallofullerenes (EMFs) is an efficient strategy to realize their ultimate applications in many fields. Herein, we report the highly regioselective and quantitative mono-formation of pyrazole- and pyrrole-ring-fused derivatives of the prototypical di-EMF Y2@C3v(8)-C82, that is, Y2@C3v(8)-C82(C13N2H10) and Y2@C3v(8)-C82(C9NH11), from the respective 1,3-dipolar reactions with either diphenylnitrilimine or N-benzylazomethine ylide, without the formation of any bis- or multi-adducts. Crystallographic results unambiguously reveal that only one [6,6]-bond out of the twenty-five different types of nonequivalent C−C bonds of Y2@C3v(8)-C82 is involved in the 1,3-dipolar reactions. Our theoretical results rationalize that the remarkably high regioselectivity and the quantitative formation of mono-adducts are direct results from the anisotropic distribution of π-electron density on the C3v(8)-C82 cage and the local strain of the cage carbon atoms as well. Interestingly, electrochemical and theoretical studies demonstrate that the reversibility of the redox processes, in particular the reversibility of the reductive processes of Y2@C3v(8)-C82, has been markedly altered upon exohedral functionalization, but the oxidative process was less influenced, indicating that the oxidation is mainly influenced by the internal Y2 cluster, whereas the reduction is primarily associated with the fullerene cage. The pyrazole and pyrrole-fused derivatives may find potential applications as organic photovoltaic materials and biological reagents. 相似文献
2.
Shuaifeng Hu Wangqiang Shen Le Yang Guangxiong Duan Prof. Peng Jin Prof. Yunpeng Xie Prof. Takeshi Akasaka Prof. Xing Lu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(49):11538-11544
Successful isolation and characterization of a series of Er-based dimetallofullerenes present valuable insights into the realm of metal–metal bonding. These species are crystallographically identified as Er2@Cs(6)-C82, Er2@C3v(8)-C82, Er2@C1(12)-C84, and Er2@C2v(9)-C86, in which the structure of the C1(12)-C84 cage is unambiguously characterized for the first time by single-crystal X-ray diffraction. Interestingly, natural bond orbital analysis demonstrates that the two Er atoms in Er2@Cs(6)-C82, Er2@C3v(8)-C82, and Er2@C2v(9)-C86 form a two-electron-two-center Er−Er bond. However, for Er2@C1(12)-C84, with the longest Er⋅⋅⋅Er distance, a one-electron-two-center Er−Er bond may exist. Thus, the difference in the Er⋅⋅⋅Er separation indicates distinct metal bonding natures, suggesting a distance-dependent bonding behavior for the internal dimetallic cluster. Additionally, electrochemical studies suggest that Er2@C82–86 are good electron donors instead of electron acceptors. Hence, this finding initiates a connection between metal–metal bonding chemistry and fullerene chemistry. 相似文献
3.
Regiospecific Coordination of Re3 Clusters with the Sumanene‐Type Hexagons on Endohedral Metallofullerenes and Higher Fullerenes That Provides an Efficient Separation Method 下载免费PDF全文
Dr. Chia‐Hsiang Chen Dong‐Yui Lin Dr. Wen‐Yann Yeh 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(19):5768-5775
The reactions of [(μ‐H)3Re3(CO)11(NCMe)] with Sc2@C82‐C3v(8), Sc2C2@C80‐C2v(5), Sc2O@C82‐Cs(6), C86‐C2(17), and C86‐Cs(16) have been carried out to produce face‐capping cluster complexes. The Re3 triangles are found to bind to the sumanene‐type hexagons on the fullerene surface regiospecifically. In contrast, Sc3N@C78‐D3h(5) and Sc3N@C80‐Ih show no reactivity toward [(μ‐H)3Re3(CO)11(NCMe)], probably due to electronic and steric factors. These complexes can be easily purified by using HPLC. Carbonylation of each complex releases the corresponding higher fullerene or endohedral metallofullerene in pure form. Remarkably, the C86‐C2(17) and C86‐Cs(16) isomers were successively separated through Re3 cluster complexation/decomplexation. This unique bonding feature may provide an attractive general strategy to purify as yet unresolved fullerene mixtures. 相似文献
4.
Sc2O@Td(19151)‐C76: Hindered Cluster Motion inside a Tetrahedral Carbon Cage Probed by Crystallographic and Computational Studies 下载免费PDF全文
Ting Yang Yajuan Hao Laura Abella Qiangqiang Tang Prof. Dr. Xiaohong Li Yingbo Wan Dr. Antonio Rodríguez‐Fortea Prof. Dr. Josep M. Poblet Prof. Dr. Lai Feng Prof. Dr. Ning Chen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(31):11110-11117
A new cluster fullerene, Sc2O@Td(19151)‐C76, has been isolated and characterized by mass spectrometry, UV/Vis/NIR absorption, 45Sc NMR spectroscopy, cyclic voltammetry, and single‐crystal X‐ray diffraction. The crystallographic analysis unambiguously assigned the cage structure as Td(19151)‐C76, which is the first tetrahedral fullerene cage characterized by single‐crystal X‐ray diffraction. This study also demonstrated that the Sc2O cluster has a much smaller Sc?O?Sc angle than that of Sc2O@Cs(6)‐C82 and the Sc2O unit is fully ordered inside the Td(19151)‐C76 cage. Computational studies further revealed that the cluster motion of the Sc2O is more restrained in the Td(19151)‐C76 cage than that in the Cs(6)‐C82 cage. These results suggest that cage size affects not only the shapes but also the cluster motion inside fullerene cages. 相似文献
5.
Synthesis and Isolation of the Titanium–Scandium Endohedral Fullerenes—Sc2TiC@Ih‐C80, Sc2TiC@D5h‐C80 and Sc2TiC2@Ih‐C80: Metal Size Tuning of the TiIV/TiIII Redox Potentials 下载免费PDF全文
Katrin Junghans Dr. Kamran B. Ghiassi Nataliya A. Samoylova Qingming Deng Marco Rosenkranz Prof. Marilyn M. Olmstead Prof. Alan L. Balch Dr. Alexey A. Popov 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(37):13098-13107
The formation of endohedral metallofullerenes (EMFs) in an electric arc is reported for the mixed‐metal Sc–Ti system utilizing methane as a reactive gas. Comparison of these results with those from the Sc/CH4 and Ti/CH4 systems as well as syntheses without methane revealed a strong mutual influence of all key components on the product distribution. Whereas a methane atmosphere alone suppresses the formation of empty cage fullerenes, the Ti/CH4 system forms mainly empty cage fullerenes. In contrast, the main fullerene products in the Sc/CH4 system are Sc4C2@C80 (the most abundant EMF from this synthesis), Sc3C2@C80, isomers of Sc2C2@C82, and the family Sc2C2 n (2 n=74, 76, 82, 86, 90, etc.), as well as Sc3CH@C80. The Sc–Ti/CH4 system produces the mixed‐metal Sc2TiC@C2 n (2 n=68, 78, 80) and Sc2TiC2@C2 n (2 n=80) clusterfullerene families. The molecular structures of the new, transition‐metal‐containing endohedral fullerenes, Sc2TiC@Ih‐C80, Sc2TiC@D5h‐C80, and Sc2TiC2@Ih‐C80, were characterized by NMR spectroscopy. The structure of Sc2TiC@Ih‐C80 was also determined by single‐crystal X‐ray diffraction, which demonstrated the presence of a short Ti=C double bond. Both Sc2TiC‐ and Sc2TiC2‐containing clusterfullerenes have Ti‐localized LUMOs. Encapsulation of the redox‐active Ti ion inside the fullerene cage enables analysis of the cluster–cage strain in the endohedral fullerenes through electrochemical measurements. 相似文献
6.
Regioselective Cage Opening of La2@D2(10611)‐C72 with 5,6‐Diphenyl‐3‐(2‐pyridyl)‐1,2,4‐triazine 下载免费PDF全文
Prof. Dr. Michio Yamada Yasuhiro Muto Dr. Hiroki Kurihara Dr. Zdenek Slanina Dr. Mitsuaki Suzuki Prof. Dr. Yutaka Maeda Prof. Dr. Yves Rubin Prof. Dr. Marilyn M. Olmstead Prof. Dr. Alan L. Balch Prof. Dr. Shigeru Nagase Prof. Dr. Xing Lu Prof. Dr. Takeshi Akasaka 《Angewandte Chemie (International ed. in English)》2015,54(7):2232-2235
The thermal reaction of the endohedral metallofullerene La2@D2(10611)‐C72, which contains two pentalene units at opposite ends of the cage, with 5,6‐diphenyl‐3‐(2‐pyridyl)‐1,2,4‐triazine proceeded selectively to afford only two bisfulleroid isomers. The molecular structure of one isomer was determined using single‐crystal X‐ray crystallography. The results suggest that the [4+2] cycloaddition was initiated in a highly regioselective manner at the C? C bond connecting two pentagon rings of C72. Subsequent intramolecular electrocyclization followed by cycloreversion resulted in the formation of an open‐cage derivative having three seven‐membered ring orifices on the cage and a significantly elongated cage geometry. The reduction potentials of the open‐cage derivatives were similar to those of La2@D2‐C72 whereas the oxidation potentials were shifted more negative than those of La2@D2‐C72. These results point out that further oxidation could occur easily in the derivatives. 相似文献
7.
Crystallographic Evidence for Direct Metal–Metal Bonding in a Stable Open‐Shell La2@Ih‐C80 Derivative 下载免费PDF全文
Lipiao Bao Dr. Muqing Chen Changwang Pan Takahisa Yamaguchi Prof. Tatsuhisa Kato Prof. Marilyn M. Olmstead Prof. Alan L. Balch Prof. Takeshi Akasaka Prof. Xing Lu 《Angewandte Chemie (International ed. in English)》2016,55(13):4242-4246
Endohedral metallofullerenes (EMFs) have novel structures and properties that are closely associated with the internal metallic species. Benzyl radical additions have been previously shown to form closed‐shell adducts by attaching an odd number of addends to open‐shell EMFs (such as Sc3C2@Ih‐C80) whereas an even number of groups are added to closed‐shell EMFs (for example Sc3N@Ih‐C80). Herein we report that benzyl radical addition to the closed‐shell La2@Ih‐C80 forms a stable, open‐shell monoadduct instead of the anticipated closed‐shell bisadduct. Single‐crystal X‐ray diffraction results show the formation of a stable radical species. In this species, the La?La distance is comparable to the theoretical value of a La?La covalent bond and is shorter than reported values for other La2@Ih‐C80 derivatives, providing unambiguous evidence for the formation of direct La?La bond. 相似文献
8.
Prof. Dr. Lai Feng Mitsuaki Suzuki Dr. Naomi Mizorogi Dr. Xing Lu Dr. Michio Yamada Prof. Dr. Takeshi Akasaka Prof. Dr. Shigeru Nagase 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(3):988-993
The dynamic positions of the dimetallic cluster inside the mid‐sized spherical cages of C80–C82 have been seldom studied, despite the high abundance of M2@C2n (2n=80, 82) species among various endohedral metallofullerenes. Herein, using crystallographic methods, we first unambiguously map the metal positions for both Ce2@D5h‐C80 and Ce2@Ih‐C80, showing how the symmetry or geometrical change in cage structure can influence the motional behavior of the cluster. Inside the D5h cage, the primary cerium sites have been identified along a cage belt of the contiguous hexagons, which suggests the significant influence of such a cage motif on endohedral cluster motion. Further analysis revealed a distorted D5h cage owing to the “punch‐out” effect of cerium atoms. The consequence is the presence of two localized electrostatic potential minima inside the cage of (D5h‐C80)6?, thus reflecting the primary ionic cerium–cage interaction. In contrast, a different motional behavior of Ce2 cluster was observed inside the Ih cage. With the major cerium sites, the molecule of Ce2@Ih‐C80 presented an approximate D2h configuration. With the combined theoretical study, we propose that the additional unidentified influence of NiII(OEP) (OEP=octaethylporphyrin) might be also relevant for the location of cerium sites inside the Ih cage. 相似文献
9.
The Unanticipated Dimerization of Ce@C2v(9)‐C82 upon Co‐crystallization with Ni(octaethylporphyrin) and Comparison with Monomeric M@C2v(9)‐C82 (M = La,Sc, and Y) 下载免费PDF全文
Prof. Mitsuaki Suzuki Prof. Michio Yamada Prof. Yutaka Maeda Dr. Satoru Sato Prof. Yuta Takano Prof. Filip Uhlík Prof. Zdenek Slanina Prof. Yongfu Lian Prof. Xing Lu Prof. Shigeru Nagase Prof. Marilyn M. Olmstead Prof. Alan L. Balch Prof. Takeshi Akasaka 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(50):18115-18122
We report that Ce@C2v(9)‐C82 forms a centrosymmetric dimer when co‐crystallized with Ni(OEP) (OEP = octaethylporphyrin dianion). The crystal structure of {Ce@C2v(9)‐C82}2?2[Ni(OEP)]?4 C6H6 shows that a new C?C bond with a bond length of 1.605(5) Å connects the two cages. The high spin density of the singly occupied molecular orbital (SOMO) on the cage and the pyramidalization of the cage are factors that favor dimerization. In contrast, the treatment of Ni(OEP) with M@C2v(9)‐C82 (M = La, Sc, and Y) results in crystallization of monomeric endohedral fullerenes. A systematic comparison of the X‐ray structures of M@C2v(9)‐C82 (M = Sc, Y, La, Ce, Gd, Yb, and Sm) reveals that the major metal site in each case is located at an off‐center position adjacent to a hexagonal ring along the C2 axis of the C2v(9)‐C82 cage. DFT calculations at the M06‐2X level revealed that the positions of the metal centers in these metallofullerenes M@C2v(9)‐C82 (M = Sc, Y, and Ce), as determined by single‐crystal X‐ray structure studies, correspond to an energy minimum for each compound. 相似文献
10.
New Trifluoromethylated Derivatives of Metal Nitride Clusterfullerenes: Sc3N@Ih‐C80(CF3)14 and Sc3N@D5h‐C80(CF3)16 下载免费PDF全文
Tao Wei Dr. Nadezhda B. Tamm Prof. Dr. Shangfeng Yang Prof. Dr. Sergey I. Troyanov 《化学:亚洲杂志》2014,9(9):2449-2452
Trifluoromethylated derivatives of Sc3N@Ih‐C80 and Sc3N@D5h‐C80 were synthesized by the reaction with CF3I at 440 °C. HPLC separation of the mixture of Sc3N@D5h‐C80(CF3)n derivatives resulted in isolation and X‐ray structure determination of Sc3N@D5h‐C80(CF3)16, which represents a precursor of the known Sc3N@D5h‐C80(CF3)18. Among the CF3 derivatives of Sc3N@Ih‐C80, two new isomers of Sc3N@Ih‐C80(CF3)14 ( Sc‐14‐VI and Sc‐14‐VII ) were isolated by HPLC, and their molecular structures were determined by X‐ray diffraction, thus enabling a comprehensive comparison of altogether seven isomers. Two types of addition patterns with different orientations of the Sc3N cluster relative to the Ih‐C80 fullerene cage were established. In particular, Sc‐14‐VII represents a direct precursor of the known Sc3N@Ih‐C80(CF3)16‐ II . All molecular structures exhibit an ordered position of a Sc3N cluster inside the fullerene C80 cage. 相似文献
11.
De‐Li Chen Dr. Wei Quan Tian Prof. Dr. Ji‐Kang Feng Prof. Chia‐Chung Sun Prof. 《Chemphyschem》2008,9(3):454-461
The complete set of 6332 classical isomers of the fullerene C68 as well as several non‐classical isomers is investigated by PM3, and the data for some of the more stable isomers are refined by the DFT‐based methods HCTH and B3LYP. C2:0112 possesses the lowest energy of all the neutral isomers and it prevails in a wide range of temperatures. Among the fullerene ions modeled, C682?, C684? and C686?, the isomers C682?(Cs:0064), C684?(C2v:0008), and C686?(D3:0009) respectively, are predicted to be the most stable. This reveals that the pentagon adjacency penalty rule (PAPR) does not necessarily apply to the charged fullerene cages. The vertical electron affinities of the neutral Cs:0064, C2v:0008, and D3:0009 isomers are 3.41, 3.29, and 3.10 eV, respectively, suggesting that they are good electron acceptors. The predicted complexation energy, that is, the adiabatic binding energy between the cage and encapsulated cluster, of Sc2C2@C68(C2v:0008) is ?6.95 eV, thus greatly releasing the strain of its parent fullerene (C2v:0008). Essentially, C68 fullerene isomers are charge‐stabilized. Thus, inducing charge facilitates the isolation of the different isomers. Further investigations show that the steric effect of the encaged cluster should also be an important factor to stabilize the C68 fullerenes effectively. 相似文献
12.
Lipiao Bao Ying Li Pengyuan Yu Wangqiang Shen Peng Jin Xing Lu 《Angewandte Chemie (International ed. in English)》2020,59(13):5259-5262
Encapsulating one to three metal atoms or a metallic cluster inside fullerene cages affords endohedral metallofullerenes (EMFs) classified as mono‐, di‐, tri‐, and cluster‐EMFs, respectively. Although the coexistence of various EMF species in soot is common for rare‐earth metals, we herein report that europium tends to prefer the formation of mono‐EMFs. Mass spectroscopy reveals that mono‐EMFs (Eu@C2n) prevail in the Eu‐containing soot. Theoretical calculations demonstrate that the encapsulation energy of the endohedral metal accounts for the selective formation of mono‐EMFs and rationalize similar observations for EMFs containing other metals like Ca, Sr, Ba, or Yb. Consistently, all isolated Eu‐EMFs are mono‐EMFs, including Eu@D3h(1)‐C74, Eu@C2v(19138)‐C76, Eu@C2v(3)‐C78, Eu@C2v(3)‐C80, and Eu@D3d(19)‐C84, which are identified by crystallography. Remarkably, Eu@C2v(19138)‐C76 represents the first Eu‐containing EMF with a cage that violates the isolated‐pentagon‐rule, and Eu@C2v(3)‐C78 is the first C78‐based EMF stabilized by merely one metal atom. 相似文献
13.
Dr. Mitsuaki Suzuki Dr. Naomi Mizorogi Tao Yang Prof. Dr. Filip Uhlik Prof. Dr. Zdenek Slanina Prof. Dr. Xiang Zhao Prof. Dr. Michio Yamada Prof. Dr. Yutaka Maeda Prof. Dr. Tadashi Hasegawa Prof. Dr. Shigeru Nagase Prof. Dr. Xing Lu Prof. Dr. Takeshi Akasaka 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(50):17125-17130
Although all the pure‐carbon fullerene isomers above C60 reported to date comply with the isolated pentagon rule (IPR), non‐IPR structures, which are expected to have different properties from those of IPR species, are obtainable either by exohedral modification or by endohedral atom doping. This report describes the isolation and characterization of a new endohedral metallofullerene (EMF), La2@C76, which has a non‐IPR fullerene cage. The X‐ray crystallographic result for the La2@C76/[NiII(OEP)] (OEP=octaethylporphyrin) cocrystal unambiguously elucidated the Cs(17 490)‐C76 cage structure, which contains two adjacent pentagon pairs. Surprisingly, multiple metal sites were distinguished from the X‐ray data, which implies dynamic behavior for the two La3+ cations inside the cage. This dynamic behavior was also corroborated by variable‐temperature 139 La NMR spectroscopy. This phenomenon conflicts with the widely accepted idea that the metal cations in non‐IPR EMFs invariably coordinate strongly with the negatively charged fused‐pentagon carbons, thereby providing new insights into modern coordination chemistry. Furthermore, our electrochemical and computational studies reveal that La2@Cs(17 490)‐C76 has a larger HOMO–LUMO gap than other dilanthanum‐EMFs with IPR cage structures, such as La2@D3h(5)‐C78 and La2@Ih(7)‐C80, which implies that IPR is no longer a strict rule for EMFs. 相似文献
14.
Dr. Ivan E. Kareev Dr. Elena Laukhina Dr. Vyacheslav P. Bubnov Dr. Vyacheslav M. Martynenko Vega Lloveras Dr. José Vidal‐Gancedo Dr. Marta Mas‐Torrent Prof. Jaume Veciana Prof. Concepció Rovira 《Chemphyschem》2013,14(8):1670-1675
We show that electron transfer from the perchlorotriphenylmethide anion (PTM?) to Y@C82(C2v) is an instantaneous process, suggesting potential applications for using PTM? to perform redox titrations of numerous endohedral metallofullerenes. The first representative of a Y@C82‐based salt containing the complex cation was prepared by treating Y@C82(C2v) with the [K+([18]crown‐6)]PTM? salt. The synthesis developed involves the use of the [K+([18]crown‐6)]PTM? salt as a provider of both a complex cation and an electron‐donating anion that is able to reduce Y@C82(C2v). For the first time, the molar absorption coefficients for neutral and anionic forms of the pure isomer of Y@C82(C2v) were determined in organic solvents with significantly different polarities. 相似文献
15.
Michio Yamada Dr. Mayuko Okamura Satoru Sato Chika I. Someya Naomi Mizorogi Dr. Takahiro Tsuchiya Dr. Takeshi Akasaka Prof. Tatsuhisa Kato Prof. Shigeru Nagase Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(40):10533-10542
The two regioisomers of endohedral pyrrolidinodimetallofullerenes M2@Ih‐C80(CH2)2NTrt (M=La, Ce; Trt=trityl) were synthesized, isolated, and characterized. X‐ray crystallographic analyses of [6,6]‐La2@Ih‐C80(CH2)2NTrt and [6,6]‐Ce2@Ih‐C80(CH2)2NTrt revealed that the encapsulated metal atoms are located at the slantwise positions on the mirror plane that parallels the pyrrolidine ring. Paramagnetic NMR analyses of [6,6]‐ and [5,6]‐Ce2@Ih‐C80(CH2)2NTrt were also carried out to clarify the metal positions. As for the [6,6]‐adduct, the metal positions obtained by paramagnetic NMR analysis agree well with the X‐ray structure. In contrast, paramagnetic NMR analysis of the [5,6]‐adduct showed that the two Ce atoms are collinear with the pyrrolidine ring. We also compared the observed paramagnetic effects of the pyrrolidinodimetallofullerenes with those of other cerium‐encapsulating fullerene derivatives such as bis‐silylated Ce2@Ih‐C80 and a carbene adduct of Ce2@Ih‐C80. We found that the metal positions can be explained by the electrostatic potential maps of the corresponding [6,6]‐ and [5,6]‐adducts of [Ih‐C80(CH2)2NTrt]6?. These findings clearly show that metal positions inside fullerene cages can be controlled by means of the addition positions of the addends. In addition, the radical anions of the pyrrolidinodimetallofullerenes were prepared by bulk controlled‐potential electrolysis and characterized by X‐band EPR spectral study. 相似文献
16.
Karolin Ziegler Konstantin Yu Amsharov Ivan Halasz Prof. Dr. Martin Jansen 《无机化学与普通化学杂志》2011,637(11):1463-1466
A report of the facile separation of C2‐C82(3) fullerene is given, which has resulted in the isolation of isomerically pure C82(3) on a preparative scale, avoiding time consuming recycling procedures. By single‐crystal X‐ray analysis of C82(3)·Ni(OEP) (Nickel octaethylporphyrine) the first crystal structure containing pristine C82(3) has been revealed. 相似文献
17.
Reaction Mechanism and Regioselectivity of the Bingel–Hirsch Addition of Dimethyl Bromomalonate to La@C2v‐C82 下载免费PDF全文
Juan Pablo Martínez Dr. Marc Garcia‐Borràs Dr. Sílvia Osuna Dr. Jordi Poater Prof. Dr. F. Matthias Bickelhaupt Prof. Dr. Miquel Solà 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(17):5953-5962
We quantum chemically explore the thermodynamics and kinetics of all 65 possible mechanistic pathways of the Bingel–Hirsch addition of dimethyl bromomalonate to the endohedral metallofullerene La@C2v‐C82 that result from the combination of 24 nonequivalent carbon atoms and 35 different bonds present in La@C2v‐C82 by using dispersion‐corrected DFT calculations. Experimentally, this reaction leads to four singly bonded derivatives and one fulleroid adduct. Of these five products, only the singly bonded derivative on C23 could be experimentally identified unambiguously. Our calculations show that La@C2v‐C82 is not particularly regioselective under Bingel–Hirsch conditions. From the obtained results, however, it is possible to make a tentative assignment of the products observed experimentally. We propose that the observed fulleroid adduct results from the attack at bond 19 and that the singly bonded derivatives correspond to the C2, C19, C21, and C23 initial attacks. However, other possibilities cannot be ruled out completely. 相似文献
18.
Dimetallic sulfide endohedral metallofullerene Sc2S@C76: Density functional theory characterization 下载免费PDF全文
Pei Zhao Tao Yang Yi‐Jun Guo Jing‐Shuang Dang Xiang Zhao Shigeru Nagase 《Journal of computational chemistry》2014,35(22):1657-1663
In terms of density functional theory combined with statistic mechanics computations, we investigated a dimetallic sulfide endohedral fullerene Sc2S@C76 which has been synthesized without any characterization in experiments. Our theoretical study reveals that Sc2S@Td(19151)‐C76 which satisfies the isolated‐pentagon rule (IPR) possesses the lowest energy, followed by three non‐IPR structures (Sc2S@C2v(19138)‐C76, Sc2S@Cs (17490)‐C76, and Sc2S@C1(17459)‐C76). To clarify the relative stabilities of those isomers at high temperatures, enthalpy–entropy interplay has been taken into consideration. Calculation results indicate that three species Sc2S@Td(19151)‐C76, Sc2S@C2v(19138)‐C76, and Sc2S@C1(17459)‐C76 have noticeable molar fractions at the fullerene‐formation temperature region (500–3000K), and the Sc2S@C1(17459)‐C76 with one pentagon pair becomes the most predominant isomer above 1800 K, suggesting that the unexpected non‐IPR structure is thermodynamically favorable at elevated temperatures. In addition, the structural characteristics, electron features, UV‐vis‐NIR adsorptions, and 13C NMR spectra of those three stable structures are introduced to assist experimental identification and characterization in future. © 2014 Wiley Periodicals, Inc. 相似文献
19.
Eighteen possible isomers of C78(CH2)2 weTe investigated by the INDO method. It was indicated that the most stable isomer was 42,43,62,63-C78(CH2)2, where the -CH2 groups were added to the 6/6 bonds located at the same hexagon passed by the longest axis of C78 (C2v), to form cyclopropane structures. Based on the most stable four geometries of C78(CH2)2 optimized at B3LYP/3-21G level, the first absorptions in the electronic spectra calculated with the INDO/CIS method and the IR frequencies of the C-C bonds on the carbon cage computed using the AM1 method were blue-shifted compared with those of C78 (C2v) because of the bigger LUMO-HOMO energy gap and the less conjugated carbon cage after the addition. The chemical shifts of ^13C NMR for the carbon atoms on the added bonds calculated at B3LYP/3-21G level were moved upfield thanks to the conversion from sp^2-C to sp^3-C. 相似文献
20.
Marc Garcia‐Borràs Dr. Sílvia Osuna Dr. Josep M. Luis Prof. Marcel Swart Prof. Miquel Solà 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(44):14931-14940
The chemical functionalization of endohedral metallofullerenes (EMFs) has aroused considerable interest due to the possibility of synthesizing new species with potential applications in materials science and medicine. Experimental and theoretical studies on the reactivity of endohedral metallofullerenes are scarce. To improve our understanding of the endohedral metallofullerene reactivity, we have systematically studied with DFT methods the Diels–Alder cycloaddition between s‐cis‐1,3‐butadiene and practically all X@Ih‐C80 EMFs synthesized to date: X=Sc3N, Lu3N, Y3N, La2, Y3, Sc3C2, Sc4C2, Sc3CH, Sc3NC, Sc4O2 and Sc4O3. We have studied both the thermodynamic and kinetic regioselectivity, taking into account the free rotation of the metallic cluster inside the fullerene. This systematic study has been made possible through the use of the frozen cage model (FCM), a computationally cheap approach to accurately predicting the exohedral regioselectivity of cycloaddition reactions in EMFs. Our results show that the EMFs are less reactive than the hollow Ih‐C80 cage. Except for the Y3 cluster, the additions occur predominantly at the [5,6] bond. In many cases, however, a mixture of the two possible regioisomers is predicted. In general, [6,6] addition is favored in EMFs that have a larger charge transfer from the metal cluster to the cage or a voluminous metal cluster inside. The present guide represents the first complete and exhaustive investigation of the reactivity of Ih‐C80‐based EMFs. 相似文献