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Angewandte Chemie International Edition 06/2011; 50(26):5909-12. · 13.45 Impact Factor
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Angewandte Chemie International Edition 11/2010; 49(50):9715-9. · 13.45 Impact Factor
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ABSTRACT: Many insoluble metallofullerenes are called missing metallofullerenes. These metallofullerenes have not yet been isolated despite their detection in raw soot using mass spectrometry. They have been anticipated to show unique structures and properties that differ considerably from those of soluble metallofullerenes. Herein, a missing metallofullerene, La@C(80), was extracted and isolated as a derivative, La@C(80)(C(6)H(3)Cl(2)). The structure of La@C(80)(C(6)H(3)Cl(2)) was determined unambiguously using single-crystal X-ray crystallographic analysis. In fact, La@C(80) has a novel C(80) cage, C(2v)-C(80) (80:3), which has not been reported. The calculation of La@C(80) with C(2v)-C(80) (80:3) cage shows that La@C(2v)-C(80) (80:3) has a radical character as well as small ionization potential (Ip) and electron affinity (Ea), which are indicative of high reactivity. On the basis of those results, La@C(2v)-C(80) (80:3) is expected to interact strongly and bond with amorphous carbon or other fullerenes in soot that is made insoluble in common organic solvents.
Journal of the American Chemical Society 08/2009; 131(31):10950-4. · 9.91 Impact Factor
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Takeshi Akasaka,
Takayoshi Kono,
Yuji Takematsu,
Hidefumi Nikawa,
Tsukasa Nakahodo,
Takatsugu Wakahara,
Midori O Ishitsuka,
Takahiro Tsuchiya,
Yutaka Maeda,
Michael T H Liu, Kenji Yoza,
Tatsuhisa Kato,
Kazunori Yamamoto,
Naomi Mizorogi,
Zdenek Slanina,
Shigeru Nagase
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ABSTRACT: We report here the results on single crystal X-ray crystallographic analysis of the Gd@C82 carbene adduct (Gd@C82(Ad), Ad = adamantylidene). The Gd atom in Gd@C82(Ad) is located at an off-centered position near a hexagonal ring in the C2v-C82 cage, as found for M@C82 (M = Sc and La) and La@C82(Ad). Theoretical calculation also confirms the position of the Gd atom in the X-ray crystal structure.
Journal of the American Chemical Society 10/2008; 130(39):12840-1. · 9.91 Impact Factor
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ABSTRACT: Dimetallofullerene Ce(2)@C(78) and its bis-silylated derivative (1) were successfully prepared and fully characterized.
Chemical Communications 03/2008; · 6.17 Impact Factor
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Michio Yamada,
Chika Someya,
Takatsugu Wakahara,
Takahiro Tsuchiya,
Yutaka Maeda,
Takeshi Akasaka, Kenji Yoza,
Ernst Horn,
Michael T H Liu,
Naomi Mizorogi,
Shigeru Nagase
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ABSTRACT: The photochemical reaction of M2@C80 (M = La and Ce) with 2-adamantane-2,3'-[3H]-diazirine (1) affords the corresponding adducts by carbene addition. The adducts were characterized by spectroscopic and single-crystal X-ray structure analyses. Crystallographic data for the adduct La2@C80(Ad) (2, Ad = adamantylidene) reveal that the two La atoms are collinear with the spiro carbon of the 6,6-open adduct. It is noteworthy that the La-La distance is highly elongated by the addition of carbene. Paramagnetic 13C NMR spectral analysis of the adduct Ce2@C80(Ad) (3) indicates that the two Ce atoms are also collinear with the spiro carbon at room temperature in solution. The unique metal positions were confirmed by density functional calculations.
Journal of the American Chemical Society 02/2008; 130(4):1171-6. · 9.91 Impact Factor
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Takatsugu Wakahara,
Michio Yamada,
Satomi Takahashi,
Tsukasa Nakahodo,
Takahiro Tsuchiya,
Yutaka Maeda,
Takeshi Akasaka,
Masahiro Kako, Kenji Yoza,
Ernst Horn,
Naomi Mizorogi,
Shigeru Nagase
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ABSTRACT: The (139)La NMR study of the exohedrally functionalized derivatives of La(2)@C(80) metallofullerene, La(2)@C(80)(Ar(2)Si)(2)CH(2) (: Ar = Mes, Mes = mesityl, : Ar = Dep, Dep = 2,6-diethylphenyl), reveal that the two La atoms hop between two sites along the equator of the C(80) cage.
Chemical Communications 08/2007; · 6.17 Impact Factor
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Yuko Iiduka,
Takatsugu Wakahara,
Koji Nakajima,
Tsukasa Nakahodo,
Takahiro Tsuchiya,
Yutaka Maeda,
Takeshi Akasaka, Kenji Yoza,
Michael T H Liu,
Naomi Mizorogi,
Shigeru Nagase
Angewandte Chemie International Edition 02/2007; 46(29):5562-4. · 13.45 Impact Factor
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Takatsugu Wakahara,
Hidefumi Nikawa,
Takashi Kikuchi,
Tsukasa Nakahodo,
G M Aminur Rahman,
Takahiro Tsuchiya,
Yutaka Maeda,
Takeshi Akasaka, Kenji Yoza,
Ernst Horn,
Kazunori Yamamoto,
Naomi Mizorogi,
Zdenek Slanina,
Shigeru Nagase
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ABSTRACT: We show here that La@C72 has a non-IPR cage, unique electronic properties, and high reactivity by the spectroscopic and X-ray crystallographic analysis and the theoretical study. The isolation of La@C72 as a stable derivative might constitute an important stepping-stone on the way to isolation of these unknown metallofullerenes and open new material science of metallofullerenes.
Journal of the American Chemical Society 12/2006; 128(44):14228-9. · 9.91 Impact Factor
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Takatsugu Wakahara,
Yuko Iiduka,
Ozora Ikenaga,
Tsukasa Nakahodo,
Akihiro Sakuraba,
Takahiro Tsuchiya,
Yutaka Maeda,
Masahiro Kako,
Takeshi Akasaka, Kenji Yoza,
Ernst Horn,
Naomi Mizorogi,
Shigeru Nagase
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ABSTRACT: The photochemical reaction of Sc(3)N@C(80) with 1,1,2,2-tetramesityl-1,2-disilirane affords the adduct as a bis-silylated product. The adduct was characterized by NMR spectroscopy and single-crystal X-ray structure analysis. The dynamic behavior of the disilirane moiety and the encapsulated Sc(3)N cluster were also investigated. The unique redox property of the adduct is reported by means of CV and DPV. Experimental results were confirmed by density functional calculations.
Journal of the American Chemical Society 09/2006; 128(30):9919-25. · 9.91 Impact Factor
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Lai Feng,
Takatsugu Wakahara,
Tsukasa Nakahodo,
Takahiro Tsuchiya,
Qiuyue Piao,
Yutaka Maeda,
Yongfu Lian,
Takeshi Akasaka,
Ernst Horn, Kenji Yoza,
Tatsuhisa Kato,
Naomi Mizorogi,
Shigeru Nagase
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ABSTRACT: The reaction of La@C82 with diethyl bromomalonate in the presence of base (the Bingel reaction) generated five monoadducts which have been fully characterized. It was found that four of them (mono-A, -B, -C, and -D) are ESR-inactive, suggesting singly bonded regioisomers. In contrast, the fifth product (mono-E) is ESR-active, indicating that it possesses a cyclic moiety between the appended malonate group and the fullerene cage, analogous to conventional Bingel adducts. The differences in the molecular structures of mono-A, -B, -C, and -E result in varying thermal stabilities and electrochemical behavior. In particular, the singly bonded monoadducts undergo the retro-Bingel reaction either under thermal treatment or during electron transfer on the cyclic voltammetric timescale. However, mono-E shows remarkable thermal stability and perfect reversibility under the same experimental conditions.
Chemistry 08/2006; 12(21):5578-86. · 5.93 Impact Factor
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Lai Feng,
Takahiro Tsuchiya,
Takatsugu Wakahara,
Tsukasa Nakahodo,
Qiuyue Piao,
Yutaka Maeda,
Takeshi Akasaka,
Tatsuhisa Kato, Kenji Yoza,
Ernst Horn,
Naomi Mizorogi,
Shigeru Nagase
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ABSTRACT: A bisadduct of La@C82 has been synthesized in a good yield by a Bingel-Hirsch reaction. Its structure has been well-defined by X-ray crystallographic analysis. A pair of enantiomers of the adduct form a dimer in the single crystal.
Journal of the American Chemical Society 06/2006; 128(18):5990-1. · 9.91 Impact Factor
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ABSTRACT: The endohedral pyrrolidinodimetallofullerene, La2@C80(CH2)2NTrt (Trt = triphenylmethyl), was successfully synthesized and characterized. X-ray crystallographic and NMR spectroscopic analyses reveal that two La atoms in the 6,6-adduct are localized at the stable site on the mirror plane. Theoretical calculation also suggests the localization of two La atoms in the 6,6-adduct.
Journal of the American Chemical Society 03/2006; 128(5):1402-3. · 9.91 Impact Factor
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Lai Feng,
Tsukasa Nakahodo,
Takatsugu Wakahara,
Takahiro Tsuchiya,
Yutaka Maeda,
Takeshi Akasaka,
Tatsuhisa Kato,
Ernst Horn, Kenji Yoza,
Naomi Mizorogi,
Shigeru Nagase
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ABSTRACT: A novel Bingel monoadduct of La@C82 (mono-A) has been synthesized by the reaction with diethyl bromomalonate in the presence of DBU (Bingel-Hirsch reaction). Its structure has been fully determined by NMR spectroscopic and X-ray crystallographic analyses. The most distinct feature of mono-A is the single bond moiety between the functional group and fullerene cage, which is very different from the cyclopropane moiety in a conventional Bingel adduct of empty fullerenes. Further spectroscopic characterizations and calculations revealed the closed-shell structure of mono-A. Its formation mechanism was discussed according to calculation results.
Journal of the American Chemical Society 01/2006; 127(49):17136-7. · 9.91 Impact Factor
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Michio Yamada,
Tsukasa Nakahodo,
Takatsugu Wakahara,
Takahiro Tsuchiya,
Yutaka Maeda,
Takeshi Akasaka,
Masahiro Kako, Kenji Yoza,
Ernst Horn,
Naomi Mizorogi,
Kaoru Kobayashi,
Shigeru Nagase
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ABSTRACT: The exohedrally functionalized derivative of endohedral metallofullerene, Ce2@C80(Mes2SiCH2SiMes2), was successfully synthesized and fully characterized. X-ray crystallographic and NMR spectroscopic analyses reveal that the free random motion of two metal atoms in Ce2@C80 is controlled inside the cage by exohedral chemical functionalization.
Journal of the American Chemical Society 11/2005; 127(42):14570-1. · 9.91 Impact Factor
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Yuko Iiduka,
Takatsugu Wakahara,
Tsukasa Nakahodo,
Takahiro Tsuchiya,
Akihiro Sakuraba,
Yutaka Maeda,
Takeshi Akasaka, Kenji Yoza,
Ernst Horn,
Tatsuhisa Kato,
Michael T H Liu,
Naomi Mizorogi,
Kaoru Kobayashi,
Shigeru Nagase
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ABSTRACT: We report here the structural determination of the Sc3C82 molecule by 13C NMR spectroscopy and X-ray single-crystal structure analysis. From the present study, it is obvious that the structure of Sc3C82 is not Sc3@C82 but Sc3C2@C80.
Journal of the American Chemical Society 10/2005; 127(36):12500-1. · 9.91 Impact Factor
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Hidefumi Nikawa,
Takashi Kikuchi,
Takatsugu Wakahara,
Tsukasa Nakahodo,
Takahiro Tsuchiya,
G M Aminur Rahman,
Takeshi Akasaka,
Yutaka Maeda, Kenji Yoza,
Ernst Horn,
Kazunori Yamamoto,
Naomi Mizorogi,
Shigeru Nagase
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ABSTRACT: The first isolation of missing metallofullerene, La@C74, as a derivative is reported. The structural determination has been performed by spectroscopic and, finally, X-ray crystallographic analysis, and the properties of La@C74 are discussed on the basis of the theoretical study.
Journal of the American Chemical Society 08/2005; 127(27):9684-5. · 9.91 Impact Factor
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Yutaka Maeda,
Yoichiro Matsunaga,
Takatsugu Wakahara,
Satomi Takahashi,
Takahiro Tsuchiya,
Midori O Ishitsuka,
Tadashi Hasegawa,
Takeshi Akasaka,
Michael T H Liu,
Kisato Kokura,
Ernst Horn, Kenji Yoza,
Tatsuhisa Kato,
Shingo Okubo,
Kaoru Kobayashi,
Shigeru Nagase,
Kazunori Yamamoto
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ABSTRACT: The photochemical reaction of La@C82 with 2-adamantane-2,3-[3H]-diazirine affords adduct 2, La@C82(Ad), in a quantitative and highly selective manner. The structure of compound 2 is confirmed by ESR, MS, and UV-vis-NIR spectroscopies, and the first X-ray crystallographic characterization of an endohedral monometallofullerene derivative is reported.
Journal of the American Chemical Society 07/2004; 126(22):6858-9. · 9.91 Impact Factor
