$\ce{Cp^-}$ is aromatic (draw the Frost diagram) when coordinated $\ce{η^5}$ on-face, or $\ce{η^1}$ non-aromatic as a simple anion coordinated on-vertex. Saturating one localized double bond leaves cyclic delocalized allyl anion coordinated $\ce{η^3}$.
In the case of $\ce{TiCp4}$, two Cp anions are face pentahapto, two are vertex monohapto. If we take a proton or C-13 NMR, will we see discrete protons or carbons for the $\ce{η^1}$-Cp, or will allowed 1,5-shifts scramble all five protons? All five carbons? Will it be temperature dependent if it happens? If it happens, will H and C have different kinetics?
$\ce{Cp^-}$ is aromatic (draw the Frost diagram) when coordinated $\ce{η^5}$ on-face, or $\ce{η^1}$ non-aromatic as a simple anion coordinated on-vertex. Saturating one localized double bond leaves cyclic delocalized allyl anion coordinated $\ce{η^3}$.
In the case of $\ce{TiCp4}$, two Cp anions are face pentahapto, two are vertex monohapto. If we take a proton or C-13 NMR, will we see discrete protons or carbons for the $\ce{η^1}$-Cp, or will allowed 1,5-shifts scramble all five protons? All five carbons? Will it be temperature dependent if it happens? If it happens, will H and C have different kinetics?
Hydrogenation of NiCp2 takes place on the ligand, not the metal, to reduce donor electron count, giving a low-energy closed-shell 18 electron count.
http://en.wikipedia.org/wiki/Nickelocene
http://en.wikipedia.org/wiki/Ferrocene
http://en.wikipedia.org/wiki/Hapticity
http://www.chem.mun.ca/homes/cmkhome/Organometallics_The%20Basics.pdf
p. 9, 10. "η" is "hapticity," the number of ligand atoms contributing pi-electron orbitals to the metal center.
$\ce{Cp^-}$ is aromatic (draw the Frost diagram) when coordinated $\ce{η^5}$ on-face, or $\ce{η^1}$ non-aromatic as a simple anion coordinated on-vertex. Saturating one localized double bond leaves cyclic delocalized allyl anion coordinated $\ce{η^3}$.
In the case of $\ce{TiCp4}$, two Cp anions are face pentahapto, two are vertex monohapto. If we take a proton or C-13 NMR, will we see discrete protons or carbons for the $\ce{η^1}$-Cp, or will allowed 1,5-shifts scramble all five protons? All five carbons? Will it be temperature dependent if it happens? If it happens, will H and C have different kinetics?
Hydrogenation of NiCp2 takes place on the ligand, not the metal, to reduce donor electron count, giving a low-energy closed-shell 18 electron count.
http://en.wikipedia.org/wiki/Nickelocene
http://en.wikipedia.org/wiki/Ferrocene
http://en.wikipedia.org/wiki/Hapticity
http://www.chem.mun.ca/homes/cmkhome/Organometallics_The%20Basics.pdf
p. 9, 10. "η" is "hapticity," the number of ligand atoms contributing pi-electron orbitals to the metal center.
$\ce{Cp^-}$ is aromatic (draw the Frost diagram) when coordinated $\ce{η^5}$ on-face, or $\ce{η^1}$ non-aromatic as a simple anion coordinated on-vertex. Saturating one localized double bond leaves cyclic delocalized allyl anion coordinated $\ce{η^3}$.
In the case of $\ce{TiCp4}$, two Cp anions are face pentahapto, two are vertex monohapto. If we take a proton or C-13 NMR, will we see discrete protons or carbons for the $\ce{η^1}$-Cp, or will allowed 1,5-shifts scramble all five protons? All five carbons? Will it be temperature dependent if it happens? If it happens, will H and C have different kinetics?
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