  It is shown that the qualitative model of the high-temperature
superconductivity suggested earlier for cuprates and doped picene and based on
the idea that the valence electron state depends on the character of the
chemical bonds they form and on the Coulomb interaction between the electrons
is not only confirmed by the experimental data on iron pnictides but is also
improved. From the chemical point of view, the high-temperature
superconductivity is associated with additional $\pi$ bonding along chains of
covalently bonded ions via a delocalized $\pi$ orbital, just like in cuprates.
From the physical point of view, as the data on iron pnictides show, the
superconductivity is associated with a FeAs layer transition into the state
similar to a macroscopic quantum system characterized by a highly correlated
electron state, formation of two-dimensional crystals of electron pairs with
quantized energy levels, and a strong Coulomb interaction between these
crystals. Superconductivity in such a system is accomplished by a
two-dimensional Wigner crystal consisting of one-dimensional Wigner crystals
formed by bosons, i.e., singlet electron pairs that are in the same
quasi-one-dimensional state extending along the ion chain, which corresponds to
a delocalized $\pi$ orbital in chemistry. The model applicability to three
different classes of materials (cuprates, picene, iron pnictides) indicates
that it can prove useful for development of the theory of superconductivity
taking into consideraion the highly correlated state of valence electrons and
strong Coulomb interactions between the electrons.
