Fulfilling the 2(N+1)2 Hirsch rule in smaller hollow fullerenes. Evaluation of long‐range magnetic behavior and NMR patterns of C28, , C24N4, and C28H4

The formation of different 32 π‐electron systems derived from a prominent small fullerene given by C₂₈, allows to evaluate several approaches ensuring an electronic shell closure in terms of the characteristic chemical shift anisotropy (CSA) and long‐range magnetic response properties for spherical aromatic compounds. Our results show that the inclusion of extra electrons and the doping of the cage, are able to sustain a long‐range shielding cone when an external field is oriented in a specific orientation. Such properties are inherent characteristics of spherical aromatic compounds, which are not obtained in the neutral C₂₈ fullerene, and in the exo‐bonded approach leading to C₂₈H₄. Thus, the doping of the cage is suggested as the most suitable approach to modify the overall count of electrons, leading to the expected response properties for further design of highly aromatic fullerenes.     

Theoretical study of fullerene derivatives: C28H4 and C28X4 cluster molecules

Based on the basic theory of C₂₈ cluster molecule proven by H. W. Kroto and the research findings of C₂₈'s derivative such as Ti@C₂₈* and Mg@C₂₈, proven by T. Guo, B. I. Dunlap, O. D. Haberlen, and others, we examine the two series fullerene derivatives, C₂₈H₄ and C₂₈X₄ cluster molecules, which are formed by the skeleton of C₂₈ cluster molecule. In this work, we not only prove that C₂₈ cluster molecule belongs to the T_d symmetry structure and its ground state is ⁵A₂ open-shell with four unpaired electrons, but also find that C₂₈ can easily react with single valence electron atoms, like hydrogen atom and halogen atoms, to be formed to stable fullerene derivatives, C₂₈H₄ and C₂₈X₄ cluster molecules (X=F, Cl, Br, I). The PM3 semiempirical molecular orbital method from G94W and Hyperchem program packages were applied very well in these fullerene derivatives. According to the results presented herein, we obtain the structures of geometrical optimization, ionization potential energy gap, heat of formation, atomization energy, and vibration frequency data of the C₂₈H₄ and C₂₈X₄ cluster molecules. The above calculation data confirm that these unknown fullerene derivatives are stable molecules; the stable behavior resembles the 1,3,5,7-tetrahaloadamantane molecules. It is quite possible that they can be synthesized experimentally in the near future. © 1998 John Wiley & Sons, Inc. Int J Quant Chem 67: 187–197, 1998     

A New Heteropolyoxotungstate with a Three-dimensional All-inorganic Framework [（C2H4N2）4（P4Co3W4O（28）H6）（H2C2O4）]n

A new heteropolyoxotungstate [(C2H4N2)4(P4Co3W4O28H6)(H2C2O4)]n with a three-dimensional framework was hydrothermally synthesized.The compound crystallizes in a tetragonal system,space group I41/a with a = 17.1006(17),b = 17.1006(7),c = 10.7525(5),V = 3144.2(2)3,Z = 4,Dc = 3.795 g·cm-3,F(000) = 3300,MoKα(λ = 0.71073 ),μ = 16.460 mm-1,the final R = 0.0335 and wR = 0.0776.In the heteropolyoxotungstate,tungsten-oxygen octahedra are linked by sharing two cis-vertexes into an infinite helical chain extending along the c axis.Cobalt atoms in the octahedral geometry act as the linkers of these chains,forming a three-dimensional framework.The cobalt and phosphorus atoms in the tetrahedral geometry play a role in stabilizing the three-dimensional framework.Ethylenediamine molecules are polymerized into organic chains which locate in the interspaces of the framework in the way of interwinding with the W-O chains.