  We present a comparative study between ReN3 and AgN3 by using density
functional theory. The ReN3 is a hypothetical compound proposed by us to
interpret the Re to Re interplanar spacing of thin films grown by sputtering.
Both, the AgN3 as the ReN3, are calculated as positive enthalpy compounds. The
enthalpy might give a clue about the spontaneous decomposition of the solid
form, but it cannot be interpreted as a restriction of its synthesizability. As
from the calculated total-energy, we discuss the route for the formation of
AgN3 starting from atomic species in aqueous solution. We propose that their
synthesizability is conditioned by the energy of free nitrogen atoms, and the
kinetics of reaction. We conclude that the intrinsic stability of a certain
atomic arrangement depends only of the equilibrium of atomic forces, and not
from the energy value associated with that structure.
