NEVER. It is a noun. I will reluctantly tolerate its use as an adjective ONLY by dentists when discussing teeth.
Or colons.
The Oxford English Dictionary disagrees with you. Their entry for impact contains transitive citations (quotes, quotations, whatever) going back to the early 17th century. The intransitive impact only goes back to 1916, so far as they can tell. If you think they are in error, I'm sure they've an address on their website you can use to correct them, and they'll update it for the next edition.