[Violagirl]

For the 1 H NMR spectrum of ferrocene, I have to figure out how the spectrum supports the sandwich structure of it over the iron atom bonded to one carbon.

I did some research to see if Fe would appear on an NMR spectrum but since iron in the ferrocene structure has a +2 charge, would it appear? Otherwise I believe only one peak appears to account for both aromatic rings as they share a covalent bond and have the same charge and should contain 5 H's to account for both rings.

My second question asks how the the 1 H NMR of acetylferrocene indicates the attachment of the acetyl group to one of the cyclopentadienyl rings.

Again, I know the peak near 4 would indicate the prescence of both aromatic rings. The singlet with three carbons would account for the methyl group found and has three carbons. However, there appears to be two additional peaks, both containing 2 hydrogens. Would that be from the carbonyl stretch and also explain the attchment of the acetyl group to one of the cyclopentadienyl rings?

Any help would be appreciated!

[Honclbrif]

"I did some research to see if Fe would appear on an NMR spectrum but since iron in the ferrocene structure has a +2 charge, would it appear?"

The charge of the metal has nothing to do with whether you can "see" that nucleus by NMR or not, that's determined by nuclear spin. It does, however, affect the shape of other peaks depending on whether the ion is paramagnetic or diamagnetic. Worth looking up if you are wondering about NMR spectra of molecules containing metal ions.

"Otherwise I believe only one peak appears to account for both aromatic rings as they share a covalent bond and have the same charge and should contain 5 H's to account for both rings."

One peak does account for both rings, and this is really the core of the argument you should be making. Why do you only see one peak? If instead of a sandwich structure, it was an Fe with cyclopentadienes hanging off it like phenyl groups, would you still only see one peak?

"My second question asks how the the 1 H NMR of acetylferrocene indicates the attachment of the acetyl group to one of the cyclopentadienyl rings."

I know the peak near 4 would indicate the prescence of both aromatic rings
Why are you assuming it's both aromatic rings? How many H's are in ferrocene? How many H's are in that singlet? Furthermore, and this is pretty important to the question at hand: if the acetyl group is attached to one of the rings, how many protons should be seen on the rings combined? If the acetyl group is attached to the Fe, how many protons should be seen on the rings combined?

The singlet with three carbons would account for the methyl group found and has three carbons.
You mean H's here. Don't confuse your nuclei.

However, there appears to be two additional peaks, both containing 2 hydrogens.
Now its time to to revisit your first assumption that the singlet near 4 ppm represents both rings.

[Violagirl]

Thanks for much! I understand now for the first question on why it supports the sandwich structure. The single peak that appears represents both rings, hence no other peaks exist to represent the Fe atom.

The single peak on the second spectrum at 4.2 ppm will account for one ring and the added two peaks, both with 2 hydrogens, show the resonances of added protons, portraying the substituted portion of the cyclopentadienide ring, showing the acetyl group. Thank you very much!!