The word/verb "manipulate" is the root or root word, and the "ion" would be affixed to it, making it a derivation of that word.
Wouldn´t be a back-formation, to my thinking, because it has a new sense (meaning) or function (like turning a noun into an adjective etc).
Back-formation sounds like having the same meaning or very close. To me the "back" in back-formation would go back to that word itself in its original ways.
But not being a linguistic I may be mistaken, others may disagree on that one. Let´s wait for further comments.https://en.wikipedia.org/wiki/Morphological_derivationhttp://grammar.about.com/od/ab/g/backformterm.htm