Textbook Exercise 9C.7

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Textbook Exercise 9C.7

Postby Adam_Ventura_1H » Sat Dec 05, 2020 2:31 pm

Unfortunately I was not able to paste the visual for this question, but the question was asking me to determine which isomers of diaminobenzene could form a chelating complex. I honestly am not sure how I would go about trying to find the chelating complex, what would be the criteria for one? Does anyone have some tips on how they would go about go about doing a similar problem.

Lea Baskin Monk 1F
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Re: Textbook Exercise 9C.7

Postby Lea Baskin Monk 1F » Sat Dec 05, 2020 3:02 pm

A chelating complex can form when there are two ligands with two spacer atoms in between them (I know that's hard to visualize so check out the picture below). In question 9C.7, the only isomer with this configuration is (b). In (a) and (c), the two ligands are too far apart from each other to both bond with a metal atom and form a chelate complex.
Screen Shot 2020-12-05 at 2.57.05 PM.png

Ayesha Aslam-Mir 3C
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Re: Textbook Exercise 9C.7

Postby Ayesha Aslam-Mir 3C » Sat Dec 05, 2020 4:24 pm

To further Lea's response, you want to look for two sites on the ligand that can realistically bond to two sites in the coordination complex- Lea did a good job describing how it's more realistic for the two groups with N that are closer to bond to the same metal in a coordination complex, so consider the locations of the bonding sites on a ligand.

This doesn't apply to this question specifically, but you should also consider lone pairs, as lone pair election repulsion is a large enough force that prevents very close sites from both bonding to a ligand. But here it might help to draw out the complex and how it would bond to a metal ion.

Anna Yang 1A
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Re: Textbook Exercise 9C.7

Postby Anna Yang 1A » Sat Dec 05, 2020 7:46 pm

One way to think of this is that the N in NH2 can form further bonds outside of those shown in the image. In lecture, we had covered a similar example to this where the N in NH2 were both bonded to Co; however, they formed a ring (pentagonal shape) in that they also bonded with C atoms that bonded with each other. If you look up chelation, there should be an image that depicts what I'm trying to describe.

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