  We study the dependence of the electronic structure of iron pnictides on the
angle formed by the arsenic-iron bonds. Within a Slater-Koster tight binding
model which captures the correct symmetry properties of the bands, we show that
the density of states and the band structure are sensitive to the distortion of
the tetrahedral environment of the iron atoms. This sensitivity is extremely
strong in a two-orbital (d_xz, d_yz) model due to the formation of a flat band
around the Fermi level. Inclusion of the d_xy orbital destroys the flat band
while keeping a considerable angle dependence in the band structure.
