Non-heme iron halogenases natively carry out C-H chlorination , and C-H bromination has been observed in vitro in SyrB2 but with lower efficiency than chlorination. This is corroborated by the abundance of chlorinated and brominated natural products. On the contrary, C-H fluorination has never been observed in any of the non-heme iron rationalize selectivity of some albeit not all non-heme iron halogenases, we also study isomer energetics and isomerization reaction coordinates (RCs) to understand the isomer energetic favorability of key intermediates such as Fe(IV)=O and Fe(III)-OH formed during the catalytic cycle with all three halides.