Coordination Compounds: doubt

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1. Dec 27, 2014

I am confused with the electron configuration of central atoms in complex salts eg. $[Fe(CN)_6]^{2-}$ configuration just Fe atom is

Now the complex is low spin so the configuration becomes,

Now we have 6CN. where will they donate their electrons? Will the donate electrons in the remaining $e_g$ to form $d^nsp^m$ or will they donate electrons in the 4s, 4p and 4d to form $sp^nd^m$ or will they have some other configuration? Can you give some exceptional cases (like for Pt all ligands are strong field and most are square planar)
I have read Crystal Field Theory and VSEPR theory. I also know Jahn-teller distorsion and Crystal field splitting.Also, the oxidation number of Fe is +4.
So will the electrons first be removed first from 4s before 3d?Is this true for all cases?
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Last edited by a moderator: Dec 27, 2014
2. Dec 27, 2014

Staff: Mentor

Are you sure about the formula?

That would be quite unusual.

3. Dec 27, 2014

It may not be possible. It's a question in J D lee inorganic chemistry... But just check if I am right.

4. Dec 27, 2014

Raghav Gupta

No, there is no formula like $[Fe(CN)_6]^{2-}$. Fe has the most stable form as $Fe^{3+}$ and sometimes forms as $Fe^{2+}$. There is formula like $[Fe(CN)_6]^{4-}$ and $[Fe(CN)_6]^{3-}$
There might be a misprinting.

5. Dec 27, 2014

I know... just assume its correct.... and lets just try to work with CFSE and CFT. Forget about periodic table.

6. Dec 27, 2014

This thread may be closed by someone because of Fe4+. I know it doesn't work that way.lets have a new Fe. I just want to know if what i'm doing is right. This has happened some times in physics forums where people are not understanding what I mean.
PF values civility
PF values grammar
PF values blah blah blah...
where is PF values creativity?
I had typed and edited the thread. It took me 20 minutes ( I could have just mugged it up but want to understand... You know, i think its the thirst for understanding that's important for a science student).
Assume its Fe4+. If you cant work with such situations, just close the thread.PF is good for advanced theories and here you value Socratic education (like chemical forums). But in my country, problem solving skills is given an emphasis. If i am not good in it, then i wont get a good college.
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Sorry if this reply seems belligerent.

Last edited: Dec 27, 2014
7. Dec 27, 2014

Raghav Gupta

Well actually my inorganic chemistry is a bit bad. So others will be able to help you in this case. I only knew in this thread that there is no formula such as $[ Fe(CN)_6]^{2-}$ .

8. Dec 27, 2014

I think it is
fecn6 "4-" not 2-. Its a mistake in the book.

9. Dec 27, 2014

Raghav Gupta

Oh sorry I didn't looked at your above consecutive reply because at that time I was typing my reply.

10. Dec 27, 2014

Raghav Gupta

We are posting at the same time in this thread is creating a mess , sorry.

11. Dec 27, 2014

Its ok.

12. Dec 27, 2014

Raghav Gupta

Well Aditya(I suppose it's your first name ) what about our previous conversations?
Sorry others as it is going one on one interaction?

13. Dec 27, 2014