Theoretical Studies of 1,3,2,4-Dithiadiazolyl Radicals

Reduction of 2+ to form 2 proceeds via the partial occupancy of the it la2 orbital of 2+ (Section III) and is accompanied by some modification of the frontier orbital energies, particularly 2bx and 4b2, which become particularly close in energy. EHMO calculations by Jprgensen indicated 2b to be higher in energy than 4b2 [91 JCS(D)1105] (a revision of that found in earlier work [89JCS(D)2229]). 

Molecular orbital (MNDO) calculations have also been carried out by 

Open-shell calculations have also been carried out on derivatives of 2 in order to compare their calculated and experimental ionization potentials (Section IX.B) (89JA1181). Although Koopman s theorem (69IJMS419) proposes an absolute correspondence between the orbital energies and the ionization potentials, it is not observed in this case the first ionization potentials are consistently some 1.5-2 eV too high. This is discussed more fully in Section IX.B. 

Thus MO calculations have, to date, allowed qualitative comparisons between theoretical and experimental data and have been used to predict the nature of the frontier orbitals. 

Isotropic ESR Data for Substituted 1,2,3,5-Dithiadiazolyl Radicals (All Coupling Constants in Milli-Teslas) 

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