De versus Pour with "for doing" expressions

Question

I've used this expression on my French mentor several times and he hasn't corrected me: "Merci pour m'avoir appelé." I've also read and heard expressions like this several times: "Merci DE m'avoir prévenu." Are the words "de" and "pour" interchangeable in this type of expression? Many thanks in advance

Accepted Answer

Bonjour Charles !  I find it strange that your French mentor didn't correct you there, because you cannot say "Merci pour + verb" in French: it will always be "merci *de* + verb".  However, you can use interchangeably "merci pour/de + noun", as such:
Merci de votre patience.Merci pour votre patience.
  I hope that's helpful! À bientôt !

Answer

Bonjour Aurélie,
Merci de m'avoir répondu!  
It seems that presence of the word "merci" changes the structure of the "for doing" phrase, am I right?  To borrow from the Level 5 "for doing lesson":
Tu auras une médaille pour avoir sauvé ce chat. = You will have a medal for saving this cat.
But if I want to say "Thanks for saving the cat" it becomes "Merci D'avoir sauve ce chat."  ??
Same thing if a pronoun is introduced?
Tu auras une médaille pour m'avoir sauvé. = You will have a medal for saving me.
BUT "Thanks for saving me" = Merci DE m'avoir sauvé.  Nest-ce pas?

This comes up a lot in everyday interaction so I want to make sure I'm getting it right!
Merci en avance, Charles

Answer

Bonjour Charles ! Yes indeed, these are two separate structures, as "merci de + infinitive" is a different expression altogether. "Pour que" in French is mostly used to express purpose = "for/in order to <doing/do something>".
Bonne journée !