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Topic: Which complex is easier to oxidize and why?  (Read 7129 times)

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Offline mistche20

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Which complex is easier to oxidize and why?
« on: January 29, 2012, 04:27:00 AM »
[Co(H2O)6]2+ is more difficult to oxidize to Co(III) than [Co(NH3)6]2+.

[Co(H2O)6]2+ is a high spin complex, and [Co(NH3)6]2+ a low spin one.

but why is the first one more difficult to oxidize than the second one?

Offline Schrödinger

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Re: Which complex is easier to oxidize and why?
« Reply #1 on: January 29, 2012, 12:44:43 PM »
The fact that the spins are different probably has a hint in it... The high spin complex has the ligands using up the 4s and 4p orbitals leaving the d orbital free with many unpaired electrons from which one can be removed rather easily to oxidize the metal ion.

On the contrary, since the low spin complex's ligands occupy the d-orbitals, with only one unpaired electron, oxidizing is a bit difficult, because it involves removing an electron from the very same d-subshell.
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Offline mistche20

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Re: Which complex is easier to oxidize and why?
« Reply #2 on: January 30, 2012, 04:50:46 AM »
The fact that the spins are different probably has a hint in it... The high spin complex has the ligands using up the 4s and 4p orbitals leaving the d orbital free with many unpaired electrons from which one can be removed rather easily to oxidize the metal ion.

On the contrary, since the low spin complex's ligands occupy the d-orbitals, with only one unpaired electron, oxidizing is a bit difficult, because it involves removing an electron from the very same d-subshell.

shouldn't that be the other way around? for the high spin complex, my guess is that since there are many electrons with the same spin, removing an electron would result in a decrease of exchange energy K. But for the low spin complex, there are less eletrons with the same spin and hence it's easier to remove it??

Offline Schrödinger

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Re: Which complex is easier to oxidize and why?
« Reply #3 on: January 30, 2012, 07:54:15 AM »
Oh! I wasnt even paying attention to what point I was making :P I'm truly sorry. Seems like I have given the exact wrong answer :P :P
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