Structural features of (C5H5)2Mo2S6 clusters: an EHMO study

1989 ◽  
Vol 67 (11) ◽  
pp. 1931-1935 ◽  
Author(s):  
Janice A. Cramer ◽  
Michael J. McGlinchey ◽  
Jean-Yves Saillard
Keyword(s):  
Molecular Orbital ◽  
Structural Features ◽  
Experimental Results ◽  
Planar Structure ◽  
Molecular Orbital Calculations ◽  
Sandwich Compounds ◽  
Extended Hückel

Extended Hückel molecular orbital calculations on S6 in the planar D6h configuration and in the bent C2v geometry reveal that the former is favored for S62+ and the latter for S64−. It is shown that the additional six electrons would populate one π* and two σ* orbitals in the planar structure. In contrast, when these hexasulfur fragments are incorporated in triple-decker sandwich compounds the pseudo-D6h structure is favored for [(C5H5)Mo(S6)Mo(C5H5)]6+ but the C2v geometry is predicted for [(C5H5)Mo(S6)Mo(C5H5)]2+ which possesses only four more electrons. The required extra two electrons are shown to originate from a metallic δ-type molecular orbital. These EHMO calculations are in complete accord with some very recent experimental results from Gillespie's laboratory. Keywords: Molybdenum–sulfur clusters, EHMO calculations.

The Electronic Absorption Spectra of Some N-Substituted Pyrroles—Molecular Orbital Calculations

1982 ◽  
Vol 36 (3) ◽  
pp. 297-301 ◽  
Author(s):  
R. Abu-Eittah ◽  
R. Hilal ◽  
M. S. El-Shall
Keyword(s):  
Absorption Spectra ◽  
Molecular Orbital ◽  
Electronic Absorption ◽  
Electronic Transition ◽  
Electronic Absorption Spectra ◽  
Experimental Results ◽  
Electronic Transitions ◽  
Molecular Orbital Calculations ◽  
Nonpolar Solvents ◽  
State Functions

The electronic absorption spectra of N-phenylpyrrole and some of its parasubstituted derivatives have been investigated in polar and nonpolar solvents. Such an investigation could predict the extent of resonance interaction between the pyrryl and phenyl moieties of the composite molecule. The direction and polarization of the electronic transitions were predicted. Molecular orbital calculations using the SCF-CI procedures were performed on N-phenylpyrrole and some of its p-substituted derivatives. The state functions and energies were computed. The weight of each configuration was evidence for the direction of the electronic transition. The correspondence between the theoretical and experimental results is satisfactory.

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