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Chemistry Forums for Students => Inorganic Chemistry Forum => Topic started by: djiang87 on November 11, 2010, 09:41:02 PM

Title: working out high spin / low spin
Post by: djiang87 on November 11, 2010, 09:41:02 PM

In my revision exercises the teacher gave us, he gives us two compounds, the first is [Fe(CN)₆]^3- and the second one is [Fe(H2O)₆]³⁺.

turns out the first one is low spin and the second one is high spin. Im not too sure how to work this out.

Title: Re: working out high spin / low spin
Post by: darko on November 11, 2010, 11:39:30 PM

CN^- cause higest octahedral split then H₂O , so energy of pairing electrons is lower then enrgy of delta_o

Title: Re: working out high spin / low spin
Post by: djiang87 on November 12, 2010, 01:08:17 AM

how would i know that CN- causes a higher octahedral split?

Title: Re: working out high spin / low spin
Post by: darko on November 12, 2010, 08:55:56 AM

there is several factors to that determine  :delta:_o , it depends on pairing energy of electrons, energy of  transition of d-electrons, charge of central metal ion. so it could not be absolute value of ligands, it is relative and is experimental data (measuring magnetic propertis or absorbtion spectra). for most comon ligands you get series

I^-<Br^-, Cl^- < SCN^- (S bonding)< F^-, OH^-<C₂O₄^2-< H₂O<SCN^-  (N bonding)<NH₃,py<en<SO₃^2-<dipy,NO₂^- (N bonding)<CN^-<CO

Title: Re: working out high spin / low spin
Post by: Trl on November 12, 2010, 09:01:03 AM

Read up on crystal field theory?

Here is a page which looked decent enough:

http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch12/crystal.php

Title: Re: working out high spin / low spin
Post by: darko on November 12, 2010, 09:23:35 AM

or you can read mentioned link :)

Title: Re: working out high spin / low spin
Post by: djiang87 on November 12, 2010, 07:28:17 PM

Thanks for the responses guys. Ive got my exam in a couple of hrs, your help was much appreciated =]