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Abstract: The equilibrium geometries, electronic structures, harmonic vibrational frequencies, and nucleus independent chemical shifts (NICS) of , Bi5M (M=Li, Na, K), and Bi5M+ (M=Be, Mg, Ca) clusters are calculated by the density functional theory (DFT) method. Our calculation show that the ground states of , Bi5M, and Bi5M+ species are predicted to be the D 5h , C 5v , and C 5v structures, respectively. In addition, the unit preserves its structural and electronic integrity in forming the Bi5M and Bi5M+ complexes. Molecular orbital analysis and NICS show that the planar (D 5h ) anion satisfies the Hükcel rule of 4n +2 π electrons and magnetic criteria for aromaticity with six delocalized π electrons and negative NICS values. The dissected NICS suggests that the aromaticity of (D 5h ) arise primarily from the contributions of Bi–Bi σ bonds and Bi–Bi π bonds, while the aromaticity of Bi5M and Bi5M+ mainly owe to the Bi–Bi σ bonds. [Copyright &y& Elsevier]

Abstract: The equilibrium geometries, energies, harmonic vibrational frequencies, and nucleus-independent chemical shifts (NICS) of the new type sandwich structures [P4MP4] n− (M=Ti, V, Cr, Mn, Fe, Co, and Ni; n =0, 1 or 2) are researched at the B3LYP/6-311G∗ and B3PW91/6-311G∗ levels of theory. The calculations reveal that the Ti, V, Cr, and Mn species adopt the eclipsed (D 4h ) conformations, while the Fe, Co, and Ni analogs adopt the staggered (D 4d ) conformations as their stable structures, and once the sandwich complexes are formed, the square properties remain unchanged. The NICS calculations confirm that the ring in the Ti, V, Cr, and Mn species exhibit σ and π antiaromaticity, while it exhibit σ and π aromaticity in the Fe, Co, and Ni analogs. [Copyright &y& Elsevier]

Abstract: The equilibrium geometries, vibrational frequencies, adiabatic energy separations for the ground and several excited states of XAl3 (X=Si, Ge, Sn, Pb) and their positive and negative ions have been investigated by the DFT level, followed by the CCSD(T) level for further energy refining, and the vertical detachment energies (VDE) for are computed and compared with the experiment and other theoretical calculations by outer valence Green function (OVGF). On the basis of our computed excited states energy separations, we have successfully suggested assignments for the observed X, A, and B states in the anion photoelectron spectra of . The assignments of the excited states are consistent excellently with the experimental excitation energies and the previous OVGF method generally. The canonical MO–NICS analysis suggest that the π and σ MOs of the (C 2v ) clusters both contribute to their aromaticity, and the π MOs contribute mostly. [Copyright &y& Elsevier]

Abstract: The equilibrium geometries, electronic structures, harmonic vibrational frequencies, and nucleus independent chemical shifts (NICS) of and Sb5M (M=Li, Na, and K) clusters are calculated by the density functional theory (DFT) method. Our calculation show that the species has the aromatic planar cyclic D 5h structure and the Sb5M species have the pyramidal C 5v structures as the ground states, and the unit preserves its structural and electronic integrity in forming the Sb5M complexes. Molecular orbital analysis and NICS show that the planar anion satisfies the Hükcel rule of 4n +2π electrons and magnetic criteria for aromaticity with six delocalized π electrons and negative NICS values. The dissected NICS suggests that the aromaticity of and Sb5M (C 5v ) arise primarily from the contributions of Sb–Sb π bonds, Sb–Sb σ bonds, and the NICS distributions and contributions, and their changing tendencies of the Sb5M (C 5v ) species are similar to the isolated anion. [Copyright &y& Elsevier]