Single Step Stone-Wales Transformation Linking Two Thermodynamically Stable Sc2O@C78 Isomers.

Among the very recently reported dimetallic oxide fullerenes Sc2O@C2n (n = 35-47), a representative Sc2O@C78 still lacks of further characterizations. Herein, a systematical investigation on Sc2O@C78 has been performed by density functional theory combined with statistical thermodynamic studies. Two isolated pentagon rule (IPR) satisfying isomers, Sc2O@D3h(24109)-C78 and Sc2O@C2v(24107)-C78, are disclosed to possess prominent thermodynamic stabilities at the temperature region of fullerene formation. Significantly, these two structures are related by a single Stone-Wales transformation. Moreover, bonding critical points, bond orders, and delocalization indices have been analyzed to uncover covalent interactions in both isomers. In addition, (13)C NMR spectra and UV-vis-NIR adsorptions of the two stable structures are introduced to assist experimental identification and characterization in the future.

[1]  Steven Stevenson,et al.  Sc2(mu2-O) trapped in a fullerene cage: the isolation and structural characterization of Sc2(mu2-O)@C(s)6-C82 and the relevance of the thermal and entropic effects in fullerene isomer selection. , 2010, Journal of the American Chemical Society.

[2]  Ning Chen,et al.  Sc2O@C(2v)(5)-C80: Dimetallic Oxide Cluster Inside a C80 Fullerene Cage. , 2015, Inorganic chemistry.

[3]  Kai Tan,et al.  Ti2C80 is more likely a titanium carbide endohedral metallofullerene (Ti2C2)@C78. , 2005, Chemical communications.

[4]  W. R. Wadt,et al.  Ab initio effective core potentials for molecular calculations. Potentials for K to Au including the outermost core orbitals , 1985 .

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

[6]  Takashi Yumura,et al.  Which do endohedral Ti2C80 metallofullerenes prefer energetically: Ti2@C80 or Ti2C2@C78? A theoretical study. , 2005, The journal of physical chemistry. B.

[7]  S. Okada,et al.  Formation of titanium-carbide in a nanospace of C78 fullerenes , 2007 .

[8]  A. Popov,et al.  Bonding in endohedral metallofullerenes as studied by quantum theory of atoms in molecules. , 2009, Chemistry.

[9]  Tao Yang,et al.  Theoretical Insight into Sc2O@C84: Interplay between Small Cluster and Large Carbon Cage. , 2015, The journal of physical chemistry. A.

[10]  J. Campanera,et al.  Bonding within the Endohedral Fullerenes Sc3N@C78 and Sc3N@C80 as Determined by Density Functional Calculations and Reexamination of the Crystal Structure of {Sc3N@C78}·Co(OEP)}·1.5(C6H6)·0.3(CHCl3) , 2002 .

[11]  S. Nagase,et al.  Sc2S@C68: an obtuse di-scandium sulfide cluster trapped in a C(2v) fullerene cage. , 2014, Physical chemistry chemical physics : PCCP.

[12]  C. Beavers,et al.  A seven atom cluster in a carbon cage, the crystallographically determined structure of Sc4(mu3-O)3@Ih-C80. , 2010, Chemical communications.

[13]  Shigeru Nagase,et al.  Quantum chemical insight of the dimetallic sulfide endohedral fullerene Sc2S@C70: does it possess the conventional D(5h) cage? , 2013, Chemistry.

[14]  R. Smalley,et al.  Fullerenes with metals inside , 1991 .

[15]  Zdenek Slanina,et al.  Addition of adamantylidene to La2@C78: isolation and single-crystal X-ray structural determination of the monoadducts. , 2008, Journal of the American Chemical Society.

[16]  Xing Lu,et al.  Carbide cluster metallofullerenes: structure, properties, and possible origin. , 2013, Accounts of chemical research.

[17]  Eiji Osawa,et al.  Can a metal-metal bond hop in the fullerene cage? , 2011, Chemistry.

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

[19]  Luis Echegoyen,et al.  Large metal ions in a relatively small fullerene cage: the structure of Gd3N@C2(22010)-C78 departs from the isolated pentagon rule. , 2009, Journal of the American Chemical Society.

[20]  S. Nagase,et al.  Quantum chemical determination of novel C82 monometallofullerenes involving a heterogeneous group. , 2014, Inorganic chemistry.

[21]  Shigeru Nagase,et al.  Di-lanthanide encapsulated into large fullerene C100: a DFT survey. , 2011, Physical chemistry chemical physics : PCCP.

[22]  Yongqiang Feng,et al.  Size effect of endohedral cluster on fullerene cage: preparation and structural studies of Y3N@C78-C2. , 2011, Nanoscale.

[23]  S. Nagase,et al.  Bonding features in endohedral metallofullerenes. Topological analysis of the electron density distribution , 1999 .

[24]  Tianming Zuo,et al.  Enhanced dipole moments in trimetallic nitride template endohedral metallofullerenes with the pentalene motif. , 2013, Journal of the American Chemical Society.

[25]  A. Popov,et al.  Vibrational structure of endohedral fullerene Sc3N@C78 (D3h'): evidence for a strong coupling between the Sc3N cluster and C78 cage. , 2006, Chemphyschem : a European journal of chemical physics and physical chemistry.

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

[27]  L. Echegoyen,et al.  Ti2S@D3h(24109)-C78: A sulfide cluster metallofullerene containing only transition metals inside the cage , 2013 .

[28]  S. Nagase,et al.  A stable unconventional structure of Sc2@C66 found by density functional calculations , 2002 .

[29]  K. Suenaga,et al.  EELS and 13C NMR characterization of pure Ti2@C80 metallofullerene. , 2001, Journal of the American Chemical Society.

[30]  Burke,et al.  Generalized Gradient Approximation Made Simple. , 1996, Physical review letters.

[31]  S. Nagase,et al.  Structural Determination on Yb@C78 Reveals an Unexpected Relationship of Yb@C2n (2n = 74–80) , 2012 .

[32]  Masahiro Kondo,et al.  Isolation, characterization, and theoretical study of La2@C78. , 2004, Journal of the American Chemical Society.

[33]  Tian Lu,et al.  Multiwfn: A multifunctional wavefunction analyzer , 2012, J. Comput. Chem..

[34]  Matthias Krause,et al.  C78 cage isomerism defined by trimetallic nitride cluster size: a computational and vibrational spectroscopic study. , 2007, The journal of physical chemistry. B.

[35]  S. Kennel,et al.  Metallofullerene drug design , 1999 .

[36]  Fred Wudl,et al.  Chemistry of Nanocarbons: Akasaka/Chemistry of Nanocarbons , 2010 .

[37]  Li Jiang,et al.  Synthesis, Isolation, Characterization, and Theoretical Studies of Sc3NC@C78-C2 , 2011 .

[38]  M. Sakata,et al.  Pentagonal-dodecahedral la2 charge density in [80-ih ]fullerene: la2 @c80. , 2001, Angewandte Chemie.

[39]  Marcel Swart,et al.  The reactivity of endohedral fullerenes. What can be learnt from computational studies? , 2011, Physical chemistry chemical physics : PCCP.

[40]  R. Whetten,et al.  Fullerene Isomerism: Isolation of C2v,-C78 and D3-C78 , 1991, Science.

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

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

[43]  Xing Lu,et al.  Chemistry of endohedral metallofullerenes: the role of metals. , 2011, Chemical communications.

[44]  Isao Ikemoto,et al.  NMR characterization of isomers of C78, C82 and C84 fullerenes , 1992, Nature.

[45]  Ning Chen,et al.  Sc2O@Td 19151)-C76 : hindered cluster motion inside a tetrahedral carbon cage probed by crystallographic and computational studies. , 2015, Chemistry.

[46]  Marilyn M. Olmstead,et al.  A distorted tetrahedral metal oxide cluster inside an icosahedral carbon cage. Synthesis, isolation, and structural characterization of Sc4(mu3-O)2@Ih-C80. , 2008, Journal of the American Chemical Society.

[47]  Eamonn F. Healy,et al.  Development and use of quantum mechanical molecular models. 76. AM1: a new general purpose quantum mechanical molecular model , 1985 .

[48]  Ning Chen,et al.  Sc2S@C2(7892)–C70: a metallic sulfide cluster inside a non-IPR C70 cage , 2013 .

[49]  Luis Echegoyen,et al.  Chemical, electrochemical, and structural properties of endohedral metallofullerenes. , 2009, Angewandte Chemie.

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

[51]  K. Maitra,et al.  erratum: Small-bandgap endohedral metallofullerenes in high yield and purity , 1999, Nature.

[52]  Ning Chen,et al.  Facile Synthesis of an Extensive Family of Sc2O@C2n (n = 35–47) and Chemical Insight into the Smallest Member of Sc2O@C2(7892)–C70 , 2014 .

[53]  H. Kroto,et al.  A mass spectrometric–NMR study of fullerene-78 isomers , 1992 .

[54]  Z. Gu,et al.  Synthesis, Isolation, and Spectroscopic Characterization of Ytterbium-Containing Metallofullerenes , 2004 .

[55]  Takeshi Akasaka,et al.  Synthesis and characterization of the D5h isomer of the endohedral dimetallofullerene Ce2@C80: two-dimensional circulation of encapsulated metal atoms inside a fullerene cage. , 2009, Chemistry.

[56]  A. Rodríguez‐Fortea,et al.  Endohedral metallofullerenes: a unique host-guest association. , 2011, Chemical Society reviews.

[57]  Shangfeng Yang,et al.  Metal nitride cluster fullerenes: their current state and future prospects. , 2007, Small.

[58]  Xiang Zhao,et al.  Dimetallic sulfide endohedral metallofullerene Sc2S@C76: Density functional theory characterization , 2014, J. Comput. Chem..

[59]  A. Balch,et al.  Crystallographic characterization of the structure of the endohedral fullerene [Er2@C82 isomer I] with C(s) cage symmetry and multiple sites for erbium along a band of ten contiguous hexagons. , 2002, Journal of the American Chemical Society.