The present invention provides compositions and methods for the selective C—H fluorination of nitrogen-containing heteroarenes with AgF2, which has previously been considered too reactive for practical, selective C—H fluorination. Fluorinated heteroarenes are prevalent in numerous pharmaceuticals, agrochemicals and materials. However, the reactions used to introduce fluorine into these molecules require pre-functionalized substrates or the use of F2 gas. The present invention provides a mild and general method for the C—H fluorination of nitrogen-containing heteroarene compounds to 2-fluoro-heteroarenes with commercially available AgF2. In various embodiments, these reactions occur at ambient temperature within one hour and occur with exclusive selectivity for fluorination at the 2-position. Exemplary reaction conditions are effective for fluorinating diazine heteroarenes to form a single fluorinated isomer.