# Chemistry doubt!

I Have got a problem.

The complex [FeF6]3- Does not have any color while [CoF6]3- Has a color.

Why? .

From theory in both the complexes d-d transition is possible

Note by Prakhar Bindal
4 years, 8 months ago

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## Comments

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exceptional case !!! Despite of five unpaired electrons the complex is coulourless. It is explained in terms of extra stability of half filled configuration due to which energy involved in electronic transiition is having shorter wavelength then the visible spectrum.

- 4 years, 8 months ago

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sorry for mass tagging

- 4 years, 8 months ago

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Abhi coordination chal raha hai

- 4 years, 8 months ago

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Friday tak khatam hoga, And maybe this will be studied in d block

- 4 years, 8 months ago

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K. go on!

- 4 years, 8 months ago

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tune mujhe tag nahi kiya ! :(

- 4 years, 8 months ago

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bhul gya tha :P

- 4 years, 8 months ago

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K, let it go . i know i am stupid ! by the way best of luck for NSEP !

- 4 years, 8 months ago

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Thanks and you aren't stupid!

- 4 years, 8 months ago

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d-d transition in [FeF6]3- are spin only and quite weak making it almost colorless. however in [CoF6]3- d-d transition from t2g to eg falls under visible region giving it a consistent blue color.

- 4 years, 8 months ago

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Yep that can be explained. but..

We mostly see colors by charge transfer and dd transition. we never see that the transitions are quite weak or so. but yeah i know it must be an exceptional case.

And neverthless thanks for answering and BTW how much are you getting in the AITS?

- 4 years, 8 months ago

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Well. This one didn't go well. No ideas why i performed so bad. What's your rank ?

- 4 years, 8 months ago

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Mine is bad too bad. in mains its 34 dont ask advanced.

what about you? And whats highest rank at your centre

- 4 years, 8 months ago

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let me give my explanation too ....High spin Fe3+ is likely with a weak field ligand like F-so this is a high spin d5 ion and no d→d transitions are possible from the 6 S ground state because there are no other sextet states possible. In the case of Co3+, this is a high spin d6 ion and the 4 D ground state is split into 4 Eg and 4 T2g states by the Oh crystal field. The only spin allowed transition will be between these states

- 4 years, 8 months ago

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i do not know how to write sub-script or superscript !

- 4 years, 8 months ago

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