Nitrogen dioxide, or NO_2NO2, is an odd-electron molecule, i.e. the number of valence electrons the molecule has is not an even number.
More specifically, nitrogen dioxide has a total of 17 valence electrons - 5 from nitrogen and 6 from each of the two oxygen atoms that comprise the molecule.
Now, VSEPR Theory can be extended to accomodate odd-electron molecules. In this case, the nitrogen dioxide molecule is considered to have a AX_2E_0.5AX2E0.5 geometry, which is right between AX_2E_0AX2E0 - linear, and AX_2E_1AX2E1 - bent.
The molecule's geometry will still be closer to bent, but the bond angle will be larger than the ideal 120^@120∘ such a geometry predicts, mostly because the oxygen atoms experience less repulsion from the single electron present on the nitrogen atom.
The actual bond angle for nitrogen dioxide is 134^@134∘. By comparison, the angle found in the nitrite ion, or NO_2^(-)NO−2, is 115.4^@115.4∘, because now nitrogen has attached a full lone pair of electrons that experience greater repulsion with the oxygen atoms.
