Structure-defining interactions in the salt cocrystals of $\mathrm{[(Me_5C_5)_2Fe^+]I_3^{-} - XC_6H_4OH}$ $\mathrm{X=Cl, I}$: weak noncovalent vs. strong ionic bonding

In the cocrystalline salts $\mathrm{[(Me_5C_5)_2Fe^+]I_3^{-}/(4\text{-}XC_6H_4OH)}$ $\mathrm{X= Cl, I}$, the directionality of $\mathrm{X \cdots I\text{-}I_2}$ halogen bonds is a significant packing factor notwithstanding their relatively low energies ($\mathrm{\sim~10~kcal~mol^{-1}}$), as compared to the fivefold stronger ionic bonding between $\mathrm{[(Me_5C_5)_2Fe^+]}$ and $\mathrm{[I_3]^{-}}$ ($\mathrm{\sim~50~kcal~mol^{-1}}$). This adds significant details to the structural landscape of $\mathrm{[(Me_5C_5)_2Fe^+]I_3}$ and offers an illustrative example of the stronger structure-defining effect of halogen bonding over the hydrogen one.