  During the presupernova evolution of massive stars, the isotopes of iron,
$^{54,55,56}$Fe, are advocated to play a key role inside the cores primarily
decreasing the electron-to-baryon ratio ($Y_{e}$) mainly via electron capture
processes thereby reducing the pressure support. Electron decay and positron
capture on $^{55}$Fe, on the other hand, also has a consequential role in
increasing the lepton ratio during the silicon burning phases of massive stars.
The neutrinos and antineutrinos produced, as a result of these weak-interaction
reactions, are transparent to the stellar matter and assist in cooling the core
thereby reducing the entropy. The structure of the presupernova star is altered
both by the changes in $Y_{e}$ and the entropy of the core material. The aim of
this paper is to report the improved microscopic calculation of Gamow-Teller
(GT$_{\pm}$) strength distributions of these key isotopes of iron using the
pn-QRPA theory. The main improvement comes from the incorporation of
experimental deformation values for these nuclei. Additionally six different
weak-interaction rates, namely electron & positron capture, electron & positron
decay, and, neutrino & antineutrino cooling rates, were also calculated in
presupernova matter. The calculated electron capture and neutrino cooling rates
due to isotopes of iron are in good agreement with the large-scale shell model
(LSSM) results. The calculated beta decay rates, however, are suppressed by
three to five orders of magnitude.
