a) What did you want to talk to me about?
b) What did you want to talk about to me?
a) Who do you want to talk to about this problem?
b) Who do you want to talk about this problem to?
I saw 1a in the TV show Grimm and the sentence set me thinking and there you go. I know sentences usually end with a preposition in English. Therefore 1a and 2b should be correct. However we've got 2 prepositions in each sentence so I'm not sure what to do and which ones would be correct. Maybe they all are. To my mind, 1a and 2a sound better but that's all I can say. How flexible is that kind of structure?