Showing papers by "Dante Macciantelli published in 1982"

Conformational studies by dynamic nuclear magnetic resonance. Part 24. Gear effect in di-isopropyl-nitrosoamine and -phenyltriazene studied by carbon-13 nuclear magnetic resonance and molecular mechanics

Abstract: Evidence of the existence of correlated intramolecular orientation (gear effect) has been observed in Pri2NNO (1) and Pri2NNNPh (2) by 13C nmr In the first case two conformers have been detected in a 92 :8 ratio at –120 °C The corresponding activation parameters have been measured (ΔG‡ 97 kcal mol–1) and the structures of the two conformers assigned Molecular mechanics calculations reproduce all the experimental observations and indicate, in addition, that this dynamic process is not synchronous but follows a two-step pathway In the case of (2) the existence of the phenomenon could be detected through the interpretation of the selective broadening of one spectral line, and the free energy of activation could be measured (ΔG‡ 102 kcal mol–1) even though the spectrum of the less populated conformer was not directly detected