Sapling Week 9

Moderators: Chem_Mod, Chem_Admin

Ruth Rosales 3D
Posts: 58
Joined: Wed Sep 30, 2020 9:44 pm
Been upvoted: 1 time

Sapling Week 9

Postby Ruth Rosales 3D » Sun Dec 06, 2020 8:23 pm

Having difficulties answering the following question:

Which geometry or geometries are common for complexes with a coordination number of 6?
trigonal bipyramidal
hexagonal planar
octahedral
pentagonal pyramidal

I answered it to be: octahedral and pentagonal pyramidal, but it is marked as wrong. Could anyone guide me or explain to me what I am doing wrong. How can I come to answer this question?

Jayasree Peri 2J
Posts: 105
Joined: Wed Sep 30, 2020 10:03 pm

Re: Sapling Week 9

Postby Jayasree Peri 2J » Sun Dec 06, 2020 8:25 pm

A coordination number of six would mean that there are six bonds with ligands. I believe your answer should also include hexagonal planar because that geometry corresponds to a molecule that has 6 ligands as well. The difference between octahedral and hexagonal planar is that octahedral has 4 ligands around and 2 above and below, whereas hexagonal planar has 6 all around.
Last edited by Jayasree Peri 2J on Sun Dec 06, 2020 8:28 pm, edited 2 times in total.

ALee_1J
Posts: 110
Joined: Wed Sep 30, 2020 9:32 pm

Re: Sapling Week 9

Postby ALee_1J » Sun Dec 06, 2020 8:25 pm

I believe pentagonal pyramidal is wrong (correct me if I'm wrong) because it's not the most efficient way. Ie, you want your electrons as far away from each other as possible. Putting five electrons together in one plane (pentagonal) doesn't minimize the electron-electron repulsion. Hexagonal planar (which also has 6) is not correct either because of the same reason of wanting to minimize the electron electron repulsion.
Last edited by ALee_1J on Sun Dec 06, 2020 8:27 pm, edited 1 time in total.

Sonel Raj 3I
Posts: 90
Joined: Wed Sep 30, 2020 9:48 pm

Re: Sapling Week 9

Postby Sonel Raj 3I » Sun Dec 06, 2020 8:26 pm

The most stable and therefore the most common shape for a complex with a coordination number of 6 would be octahedral. Almost all complexes with a coordination number of 6 are octahedral complexes, and you typically would not see any other shapes.

keely_bales_1f
Posts: 94
Joined: Wed Sep 30, 2020 9:41 pm

Re: Sapling Week 9

Postby keely_bales_1f » Sun Dec 06, 2020 8:28 pm

The answer is just octahedral. Octahedral is a COMMON shape for the coordination number 6. I think when I looked at the explanation for this problem it said that pentagonal pyramidal was not common.

Diana Aguilar 3H
Posts: 90
Joined: Wed Sep 30, 2020 9:50 pm

Re: Sapling Week 9

Postby Diana Aguilar 3H » Sun Dec 06, 2020 10:54 pm

The most common geometry for a complex with a coordination number of 6 would just be octahedral.

rhettfarmer-3H
Posts: 101
Joined: Wed Sep 30, 2020 9:59 pm

Re: Sapling Week 9

Postby rhettfarmer-3H » Sun Dec 06, 2020 11:26 pm

You are right in a way. Octahedral is the most common coordination number 6 geometry for most. The hexagonal planner is not common in most structures because the repulsion is not great for it is a regular structure so that's why it gets ruled out. The others are not coordination number 6 they are 5. Hence, the question asks for regular structure for coordination number 6 so that's why octahedral wins the race.


Return to “Shape, Structure, Coordination Number, Ligands”

Who is online

Users browsing this forum: No registered users and 1 guest