Organogermatranes and their cation radicals by EPR-spectroelectrochemistry and ab initio calculations

Electron Transfer and Modification of Oligosilanylsilatranes and Related Derivatives

“…those where the oxidation affects the atrane cage, and the others, with a substituent whose own oxidation potential is lower than that of the atrane unit. 13 …”

“…8 What happens with this unusual bond upon electron withdrawal, for instance during electrooxidation, is of a great interest (for classical bonds see ref (9)) but is not known so far. Only scarce reports exist on the oxidation of 1-organosilatranes, 10−12 though preliminary data on the cation radicals of organogermatranes 13 suggest it might be very insightful.…”

Theoretical study of the geometrical, energetic and NMR properties of atranes

“…The exchange correlation functional of Perdew was employed with large orbital basis sets of contracted Gaussian-type functions. Other germatranes and their cation radicals were studied by EPR and calculated theoretically at the B3LYP/LANL2DZ level [25]. The vibrational spectra of silatranes and germatranes was calculated at the B3LYP and MP2 methods with the aug-cc-pVDZ basis set [26].…”

Covalent Grafting of Silatranes to Carbon Interfaces

“…Comparison of electrooxidation of known silatranes18 and germatranes19–21 leads to the counterintuitive observation that aryl substitution at Si (or Ge) does not cause any remarkable difference in the stability of their cation radicals formed by one‐electron oxidation,18, 21, 22 compared to alkyl derivatives. A closer look at the electronic structure of these species shows that this behavior stems from the space orientation of the HOMO‐forming 3 c–4 e system of metallatranes.…”

“…Indeed, EPR spectroelectrochemical investigations and DFT calculations of the cation radicals of aryl and vinyl‐substituted silatranes (just as in CH 3 , CC, and CC substituted germatranes),21 spin density was shown to remain on the atrane N atom without any visible delocalization over the unsaturated substituent (Scheme ) 22. In benzyl‐substituted silatranes and germatranes,19, 21, 22 the phenomenon of “spin‐leakage” from the atrane cage into the aromatic system of the benzyl substituent was observed: electron withdrawal affects the HOMO of the 3 c–4 e orbital combination but the resulting unpaired electron (SOMO) is mostly located (> 65 %)21 on the substituent (Scheme ). The key to this phenomenon is efficient hyperconjugation between the SiC bond (external fragment of the 3 c–4 c N⋅⋅⋅SiC system) and π‐electrons of Ph.…”