Coordination number of 6

[Dongfang Tian 1L]

For complexes with a coordination number of 6, their geometry is octahedral, I wonder why hexagonal planar is wrong so can somebody explain this to me?

[AnoushkaBhat2J]

Hello! I'm not sure if this is right but I don't think that was one of the shapes covered in VSEPR theory (since we went up to octahedral, which is bonds). For the coordination number of 4 however, tetrahedral and square planar both have 4 bonds with different lone pair numbers. However, I'm not sure why seesaw is not a viable option, since that shape also has 4 bonds and one lone pair. If someone can explain why coordination compounds only have certain shapes and not others, that would be very helpful! Thank you!

[Madison Yee 2B]

Hexagonal planar is not one of the VSEPR shapes. Although it may seem like all of the molecules are on the same plane based on how we draw the Lewis structures, this is actually not the case. In reality, the lone pairs on each of the molecules repel each other, so they need to be a certain angle apart from each other. In the case of the octahedral shape, all of the molecules are 90 degrees apart from each other.