Duden webpage for Lieblings prefix, in German

Google translate for a rough translation of the above webpage

No, unfortunately the sentence you suggest is not possible.

In einer neutralen Aussage ist die Verneinung "nicht" hier nicht möglich oder nicht üblich. Sie wird dann verwendet, wenn die Verneinung kontrastierend ist.

Source

another Link

Well, one day you may read "Wir können nicht Freunde sein." IF a contrasting part follows or is strongly implied, like "Wir können nicht Freunde sein, aber Eltern." for example.

I'll give you a list of correct examples to point out the differences in grammar caused by indefinite articles, singular/plural ect.

• "Er hat keinen Freund." (negation of "Er hat einen Freund."; indefinite, singular)
• "Er hat keine Freunde." (negation of "Er hat Freunde."; indefinite, plural)
• • Note that there is no indefinite article in the plural sentence unless it is negated!

• "Er hat nicht einen Freund." (It's emphasized here that he really doesn't have one friend.)

• "Er hat keinen Freund, aber/sondern einen Feind."

• • ("He doesn't have a friend but an enemy.")
• "Er hat keinen Freund, aber/sondern Feinde."
• "Er hat keine Freunde, aber/sondern einen Feind."
• "Er hat keine Freunde, aber/sondern Feinde."
• "Er hat nicht Freunde, sondern Feinde."
• • The only occassion I heard sentences like this is if someone explains a word to a child. The focus is on the word itself (e.g.: it's correct pronounciation) and not the meaning.
• "Er hat nicht Freund, sondern Feind." as well as "Er hat nicht Freund, nicht Feind." are expressions you can find in really old texts and are definitely not used anymore.

I know that the contrast of "ein/kein", "mit/ohne", "für/gegen" ect. are very difficult - and I really mean it - so please don't get discouraged. German children often struggle with some of the 'rules' (and/or their exceptions), too. My little sister always used to say "mit ohne" instead of "ohne". E.g.: "Wir gehen mit ohne Mama." which is correctly "Wir gehen ohne Mama.". (After learning "without" in English class, I understood the logic my sister instinctively followed back then.)