In the northern part of Iran, in Mazandaran, we negate like this (this is the only verb being used like this as far as I'm aware of):
bɜtʊ̈ndɜ: he/she can
bætʊ̈ndɜ: he/she can't
is there anything like it in other Indo-European languages?
edit: another example can be:
bænʃɜnɜ --> Persian: nɜmɪʃævæd meaning "it is not possible (to happen)"
bɜnʃɜnɜ --> Persian: mɪʃævæd meaning "it is possible (to happen)"