  We present an analysis of the electronic structure of perovskite-related
iridates, 5d electron compounds where a subtle interplay between spin-orbit
coupling, tetragonal distortions and electron correlations determines the
electronic structure properties. We suggest via electronic structure
calculations that a non-collinear calculation is required to obtain solutions
close to the usually quoted $j_{eff}$ = 1/2 state to describe the $t_{2g}$ hole
in the $Ir^{4+} :d^5$ cation, while a collinear calculation yields a different
solution, the hole is in a simpler xz/yz complex combination with a smaller
$L_z /S_z$ ratio. We describe what the implications of this are in terms of the
electronic structure; surprisingly, both solutions barely differ in terms of
their band structure, and are similar to the one obtained by a tight binding
model involving $t_{2g}$ orbitals with mean field interactions. We also analyze
how the electronic structure and magnetism evolve with strain, with the
spin-orbit coupling strength and with the on-site Coulomb repulsion, suggest
the way the band structure gets modified and draw some comparisons with
available experimental observations.
