deshielding effects

[TimeforDAT]

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Can someone explain why a compound like CH3I3 has a more deshielding effect than a compound like CH3Cl3, which will cause it to have a more downfield signal on the H NMR spec

Does it have something to do with the iodide being larger is more deactivating?

 

[whoaaitzkyle]

Can someone explain why a compound like CH3I3 has a more deshielding effect than a compound like CH3Cl3, which will cause it to have a more downfield signal on the H NMR spec

Does it have something to do with the iodide being larger is more deactivating?

electron withdrawing groups deshield the nucleus because it pulls its electron cloud away from it. In doing so, the nucleus will resonate at a lower field. Look for the most electron withdrawing atoms and that will cause the most downfield signal.

 

[Decan]

Wouldnt CH3Cl3 be more downfield since Cl is more electronegative?

 

[TimeforDAT]

Wouldnt CH3Cl3 be more downfield since Cl is more electronegative?

thats what i thought at first.

but maybe i'm thinking it has to do with the iodide ions being bigger?

this question is from achiever test 1, but it doesn't go into as why CH3I3 is more downfield as opposed to CH3Cl3

 

[Decan]

thats what i thought at first.

but maybe i'm thinking it has to do with the iodide ions being bigger?

this question is from achiever test 1, but it doesn't go into as why CH3I3 is more downfield as opposed to CH3Cl3

I dont Iodine's size explains why it would have a stronger deshielding effect..it explains why it is a good leaving group, but not when it comes to electronegativity.

I dont know...can someone elaborate?