Synthesis and characterization of the D5h isomer of the endohedral dimetallofullerene Ce2@C80: two-dimensional circulation of encapsulated metal atoms inside a fullerene cage.

Herein we show the synthesis and characterization of the second known Ce(2)@C(80) isomer. A (13)C NMR spectroscopic study revealed that the structure of the second isomer has D(5h) symmetry. Paramagnetic NMR spectral analysis and theoretical calculation display that the encapsulated Ce atoms circulate two-dimensionally along a band of ten contiguous hexagons inside a D(5h)-C(80) cage, which is in sharp contrast to the three-dimensional circulation of two Ce atoms in an I(h)-C(80) cage. The electronic properties were revealed by means of electrochemical measurements. The D(5h) isomer of Ce(2)@C(80) has a much smaller HOMO-LUMO gap than cluster fullerenes (M(3)N@C(80), M = Sc, Tm, and Lu) with the same D(5h)-C(80) cages. The chemical reactivity was investigated by using disilirane as a chemical probe. The high thermal reactivity toward 1,1,2,2-tetramesityl-1,2-disilirane is consistent with the trends of the redox potentials and the lower LUMO level of the D(5h) isomer of Ce(2)@C(80) compared with that of C(60).

[1]  S. Nagase,et al.  Positional control of encapsulated atoms inside a fullerene cage by exohedral addition. , 2005, Journal of the American Chemical Society.

[2]  Parr,et al.  Development of the Colle-Salvetti correlation-energy formula into a functional of the electron density. , 1988, Physical review. B, Condensed matter.

[3]  H. W. Kroto,et al.  The stability of the fullerenes Cn, with n = 24, 28, 32, 36, 50, 60 and 70 , 1987, Nature.

[4]  Steven Stevenson,et al.  Rapid removal of D(5)(h) isomer using the "stir and filter approach" and isolation of large quantities of isomerically pure Sc(3)N@C(80) metallic nitride fullerenes. , 2007, Journal of the American Chemical Society.

[5]  Y. Maruyama,et al.  Electrochemistry and Ab Initio Study of the Dimetallofullerene La2@C80 , 1995 .

[6]  Y. Achiba,et al.  Synthesis of the First Adducts of the Dimetallofullerenes La2@C80 and Sc2@C84 by Addition of a Disilirane , 1995 .

[7]  Shihe Yang,et al.  Isolation and Characterization of the Dimetallofullerene Ce2@C80 , 1996 .

[8]  Á. Pérez‐Jiménez.  Molecular Electronics with Endohedral Metallofullerenes : The Test Case of La2@C80 Nanojunctions , 2007 .

[9]  S. Nagase,et al.  Organic chemical derivatization of fullerenes. 2. Photochemical [2 + 3] cycloaddition of C60 with disiliranes , 1993 .

[10]  Tianming Zuo,et al.  Preparation and structural characterization of the Ih and the D5h isomers of the endohedral fullerenes Tm3N@C80: icosahedral C80 cage encapsulation of a trimetallic nitride magnetic cluster with three uncoupled Tm3+ ions. , 2008, Inorganic chemistry.

[11]  A. Fujiwara,et al.  Conductivity and field effect transistor of La2@C80 metallofullerene. , 2003, Journal of the American Chemical Society.

[12]  Takeshi Akasaka,et al.  Synthese der ersten Addukte der Dimetallofullerene La2@C80 und Sc2@C84 durch Addition eines Disilirans , 1995 .

[13]  Matthias Krause,et al.  Expanding the world of endohedral fullerenes--the Tm3N@C2n (39< or =n< or =43) clusterfullerene family. , 2005, Chemistry.

[14]  Tianming Zuo,et al.  Structure and enhanced reactivity rates of the D5h Sc3N@C80 and Lu3N@C80 metallofullerene isomers: the importance of the pyracylene motif. , 2006, Journal of the American Chemical Society.

[15]  Y. Lian,et al.  Analysis of lanthanide-induced NMR shifts of the Ce@C82 anion. , 2006, Journal of the American Chemical Society.

[16]  Shigeru Nagase,et al.  Endofullerenes : a new family of carbon clusters , 2002 .

[17]  S. Nagase,et al.  Adduct of C70 at the Equatorial Belt: Photochemical Cycloaddition with Disilirane , 1994 .

[18]  Matthias Krause,et al.  Isolation and characterisation of two Sc3N@C80 isomers. , 2004, Chemphyschem : a European journal of chemical physics and physical chemistry.

[19]  S. Nagase,et al.  Exohedral adducts of La@C82 , 1995, Nature.

[20]  Hideyuki Funasaka,et al.  13C and 139La NMR Studies of La2@C80: First Evidence for Circular Motion of Metal Atoms in Endohedral Dimetallofullerenes , 1997 .

[21]  S. Nagase,et al.  Chemical reactivity of sc3n @ c80 and la2 @ c80. , 2005, Journal of the American Chemical Society.

[22]  Marilyn M. Olmstead,et al.  Isolation and Structural Characterization of a Family of Endohedral Fullerenes Including the Large, Chiral Cage Fullerenes Tb3N@C88 and Tb3N@C86 as well as the Ih and D5h Isomers of Tb3N@C80 , 2007 .

[23]  S. Nagase,et al.  Chemical derivatization of endohedral metallofullerene La@C82 with digermirane , 1996 .

[24]  R. Kaner,et al.  Lanthanum carbide (La2C80): a soluble dimetallofullerene , 1991 .

[25]  R. Kaner,et al.  Collisional probes and possible structures of La2C80 , 1992 .

[26]  Takeshi Akasaka,et al.  13C‐ und 139La‐NMR‐Untersuchungen an La2@C80 — der erste Nachweis kreisförmiger Bewegungen von Metallatomen in endohedralen Dimetallofullerenen , 1997 .

[27]  Thomas R. Cundari,et al.  Effective core potential methods for the lanthanides , 1993 .

[28]  J. Ding,et al.  Isolierung und Charakterisierung des Dimetallofullerens Ce2@C80 , 1996 .

[29]  A. Becke,et al.  Density-functional exchange-energy approximation with correct asymptotic behavior. , 1988, Physical review. A, General physics.

[30]  S. Nagase,et al.  Exohedral derivatization of an endohedral metallofullerene Gd@C82 , 1995 .

[31]  S. Nagase,et al.  Spectroscopic and theoretical study of endohedral dimetallofullerene having a non-IPR fullerene cage: Ce2@C72. , 2008, The journal of physical chemistry. A.

[32]  J. Larsson,et al.  Explanation of the different preferential binding sites for Ce and La in M2@C80 (M = Ce, La)—a density functional theory prediction , 2008 .

[33]  P. C. Hariharan,et al.  The influence of polarization functions on molecular orbital hydrogenation energies , 1973 .

[34]  Shangfeng Yang,et al.  A large family of dysprosium-based trimetallic nitride endohedral fullerenes: Dy3N@C2n (39 , 2005, The journal of physical chemistry. B.

[35]  T. Glass,et al.  An isomer of the endohedral metallofullerene Sc3N@C80 with D5h symmetry , 2003 .

[36]  Shigeru Nagase,et al.  Elektrochemische und ab‐initio‐Untersuchung des Dimetallofullerens La2@C80 , 1995 .

[37]  S. Nagase,et al.  ESR study on the reactivity of two isomers of LaC82 with disilirane , 1996 .

[38]  A. Becke.  Density-functional thermochemistry. III. The role of exact exchange , 1993 .

[39]  Takeshi Akasaka,et al.  Location of the metal atoms in Ce2@C78 and its bis-silylated derivative. , 2008, Chemical communications.