Search for a trans-Disulfide: Structural Analysis of Di-tert-adamantyl Disulfide by Photoelectron Spectroscopy, Derivation of σI (t-Ad), and Molecular Mechanics Calculations for Related Bulky Disulfides
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Photoelectron spectroscopy of t-Ad-SS-t-Ad yields an IE(n) - IE(n+) energy difference of 0.51 eV at the frontier orbital gap suggesting to an S-S dihedral angle of θ(CSSC) = 103°. Molecular mechanics calculations with Allinger's MMI yield a shallow energy minimum with respect to rotation about the S-S bond. Two conformations differing by 0.7 kcal/mol are located at θ(CSSC) = 100 and 114°. Regression analysis of dialkyl disulfide ionization energies and substituent inductive parameters (σI) leads to σ(t-Ad) = -0.089, indicating t-Ad to be a better electron donor than t-Bu. Finally force field calculations for several sterically congested disulfides suggest that trans disulfides may be realizable for very large alkyl substituents such as the (t-Bu)3C, polymethyladamantyl, and trimethylperhydrotriquinicenyl moieties.
|Journal||Journal of Organic Chemistry|
|Number of pages||6|
|Publication status||Published - 1 Jan 1980|