The structure and stereodynamics of N,N-bis(silyloxy)enamines (1), a new class of enamines with extraordinary reactivity, have been simulated by the DFT PBE/TZP method. The computed pattern of dynamic behavior and structural peculiarities of 1 was shown to reflect adequately the results of the studies by a series of physical methods including X-ray analysis and dynamic NMR and UV spectroscopies, which provided evidence of a rather low barrier for rotation around the C,N single bond, a negligible contribution of the n-pi-conjugation, a high barrier of inversion, and high pyramidality of the nitrogen atom.

The formation and decomposition pathways of germiranes (germacyclopropanes), i.e., products of reactions of the GeH 2 and GeMe 2 germylenes with ethylene, tetramethylethylene, buta 1,2,3 triene, and tetramethylbuta 1,2,3 triene, were studied using the density functional approach (PBE/TZ2P approximation). The thermodynamic stabilities of the structures under consideration were evaluated by calculating the Gibbs free energies under normal condi tions (∆G°2 98 ). Addition of germylenes to the C=C bond can proceed as a single step process without a barrier or involve the formation of a π complex (the barrier to this process is lower than the sum of the energies of isolated reactants). Stability of the germiranes formed is determined by their stability to retrodecomposition into the initial germylene and olefin and to the three membered ring opening followed by simultaneous 1,2 migration of the substituent at the Ge atom and formation of the secondary germylene. Alkyl substituents can efficiently block the opening of the three membered ring and transformation of the cyclic structure into the secondary germylene, simultaneously decreasing the germirane stability to retrodecomposition. Decomposition into germylene and olefin under normal conditions is thermally favorable for hexamethylgermirane (∆G°2 98 = -5.7 kcal mol -1 ), being thermally forbidden for the other germiranes studied in this work (∆G°2 98 > 0). The activation energy (E a ) for the germirane ring opening depends on the substituents at the germanium atom, namely, E a ≤ 10 kcal mol -1 for unsubstituted germiranes and E a > 30 kcal mol -1 for methyl substituted germiranes. Taking the experimentally isolated germirane as an example, it was shown how the introduction of sub stituents and modification of the carbon skeleton make it possible to stabilize the germa cyclopropane system.