Why does Iodine form Cations sometimes?

It is reported that iodine forms compounds like $\ce{(CH3COO)3I}$, $\ce{I(ClO4)3}$ and $\ce{IPO4}$ which contains $\ce{I+}$ and $\ce{I^3+}$ and are not bonded covalently as in interhalogen compounds.

Generally, Halogens form anions of the type $\ce{X-}$ to achieve stability by attaining noble gas configuration. However iodine loses electrons when it forms a cation and does not attain noble gas configuration. So why does iodine form cations while no other halogen does?

• Why should iodine not form cations? Fluorine cations can be supplied (albeit not stable for extended periods of time). Thus, any atom can likely form cations, although it is unproven for helium and neon as far as I know. – Jan Nov 13 '15 at 16:51
• You should check your data - all three compounds are covalent. Doubt if you can find any solid data on any +3 cation which isn't coordinated to ligands. – Mithoron Dec 14 '15 at 1:44