| Popis: |
Structures and energies of tautomeric forms of C and N -nitro compounds (MeCH 2 NO 2 ( I ) and MeNHNO 2 ( II )) were determined by an ab initio MO study at the HF/6–31G ∗ //6–31G level. The geometry optimization of I , II , and their tautomeric ( E,Z ) and ( Z,Z ) nitronic acids. III and IV , respectively, was performed. Structures, energies, and proton affinities of the C and N -nitro anions (MeCHNO − 2 ( V ) and MeNNO − 2 ( VI ), which are intermediates in transformations I → III and II → IV , respectively, were also determined. Z,Z - III and Z,Z - IV were calculated to be 18.4 kcal mol −1 and 14 kcal mol −1 less stable than I and II , respectively, the ( Z,Z ) isomers of III and IV being the most stable. The structure of II also optimized at the 6–431G ∗ //6–31G ∗ level was estimated to be essentially non-planar. The reason for the high kinetic instability of IV is discussed. |
