Bond Angles of Isomer

[Teleologist]

How many unique bond angles are there in the isomer of BrPF4 with the "Br" axial?

I chose 3.

Answer is 4.

Where did this fourth, unique bond angle come from?

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[KVS]

This molecule would assume a trigonal bipyramidal shape which has the 3 unique angles you mentioned. The only thing I could think of to explain the fourth angle would be complex and you would have to use more than one Berry mechanisms. It seems out of scope for the mcat though. Where did you get this question from?

 

[Blueprint MCAT Tutor]

This is a really interesting question and one I don't know off the top of my head, but I've got my educated guess. Answer here, with a crappy picture:

http://forums.studentdoctor.net/threads/specific-science-questions.1053558/

 

[Teleologist]

Thanks. I have another similar question about the number of different bond angles for F3PCl2 with the Cl atoms equatorial...I get 4. Book says 5. What's up? Hopefully this second question provides some insight.