Octahedral bond angle question

Practice Question Solving
1

Hi,

I always learned that the bond angles in an octohedral structure are all 90°, i have seen some textbooks say there’s and extra 180° bond as well between the top and bottom element, as shown bellow.
Is this incorrect or too advanced for the exam?
What bond angles should we learn?

Thank you!

xebr2f4_bond_angles7546676083479800839
xebr2f4_bond_angles7546676083479800839167×219 12.7 KB

2

the book just wants to let us know that if we skip one element its 180* and that the overall 3d shape is made of right angles.