Conformations of Hydrazine and Hydrogen Peroxide

Rotation around the NN bond in hydrazine yields three staggered conformers, one in whieh the lone pairs are anti and the other two (equivalent struetures) in which they are gauche. 

A related molecule is hydrogen peroxide. Again, it might be expected that rotation (around the oxygen-oxygen bond) would lead to three all-staggered conformers. 

Summarize your observations on the conformations of molecules with lone pairs. 

Electrostatic potential map for trimethylammonium ion shows most positively-charged regions (in blue) as likely acidic sites. 

The model dealt with here is greatly oversimplified, and is only of qualitative value. It treats solvation on the ammonium ions in terms of a single layer (or shell) of solvent, and ignores solvation of neutral ammonia and trimethylamine. 

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The validity of the Lemieux-Chii interpretation was entirely supported, and the picturesque rabbit-ear idea shown untenable, by a theoretical study that used an ab initio (Hartree-Fock) calculation, with fluoromethanol as the model compound. The calculations showed that the stable conformation has the C-F bond trans to one electron pair and gauche to another, whereas the conformation in which the C-F bond bisects the electron pairs is the energy maximum. Similar interpretations were established for hydrazine, hydroxylamine, and hydrogen peroxide. The concept can be stated in general terms as a destabilization of a conformation that places a polar (C-X) bond eclipsed between two electron pairs. 

Like hydrogen peroxide the inorganic substances hydrazine (H2NNH2) and hydroxylamine (H2NOH) possess conformational mobility Wnte stmctural representations or build molecular models of two different staggered conformations of (a) hydrazine and (b) hydroxylamine... 

Ferraro and coll, used canonical transformation of the Hamiltonian to resolve the average optical rotatory power of a molecule into atomic contributions, based on the acceleration gauge for the electric dipole, and/or the torque formalism [151], This method has been applied to the study of the conformational profile of the optical rotatory poser of hydrogen peroxide and hydrazine [152]. 

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