Why does $\ce{[Co(NO2)6]4-}$ ion have 3 unpaired electron as opposed to 1?

The book says that it has 3 unpaired electrons. I thought $\ce{NO2-}$ was a strong field ligand, making $\ce{Co^2+}$ a $\ce{d^7}$ low spin ion. Six electrons go in the $\mathrm{t_{2g}}$ orbital and 1 in the $\mathrm{e_g}$ orbital.

  • $\begingroup$ You can't predict which ligand is strong or weak, there are many factors which can change this. $\endgroup$ – King Tut Feb 13 '18 at 12:32
  • $\begingroup$ An easier method - instead of getting tangled in the mess of strong vs weak field ligand - would be to make deductions based on the compound's calculated paramagnetic moments. Unfortunately, a simple Google search yields too little information. Perhaps, the chemists with more efficient database searches can help out here? $\endgroup$ – Gaurang Tandon Mar 15 '18 at 15:51

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.