-1
$\begingroup$

I know EFFECTIVE ATOMIC NUMBER (EAN) as the following

• The sum of the number of electrons, donated by all ligands and those present on the central metal ion or atom in the complex is called an effective atomic number (EAN).

EAN = [(atomic number of central metal) – (the oxidation state of the metal) + (the number of electrons gained by the metal from the ligands through co-ordination)]

I need for this component $\ce{{[Fe(diars)}2{Cl}2]Cl}$

I saw (diars) & couldn't calculate it

Edit 1 Thanks to Mathew Mahindaratne comment

EAN = [(atomic number of central metal) – (the oxidation state of the metal) + (the number of electrons gained by the metal from the ligands through co-ordination)]

EAN = $\ce{26 – 3 + (2*4 + 2*2) = 35}$

The question is do I take the 2 electrons that came from Cl2?

$\endgroup$
3
  • 2
    $\begingroup$ The metal complex you need to consider here is $\ce{[Fe(diars)2Cl2]+}$. each $\ce{diars}$ donate $\ce{4e-}$. Now you can calculate EAN ($\ce{diars}$ is 1,2-bis(dimethylarsino)benzene). $\endgroup$ – Mathew Mahindaratne Feb 20 at 21:20
  • $\begingroup$ is it correct now? $\endgroup$ – A.Hany Feb 21 at 23:10
  • $\begingroup$ It is correct now. Yes, you have to count all electrons from ligands in the complex ion so should count electrons from $\ce{2Cl-}$ ions as well. $\endgroup$ – Mathew Mahindaratne Feb 22 at 0:09
0
$\begingroup$

In your oxidation state calculation you render chlorine in the complex as $\ce{Cl^-}$, which then donates two electrons to the central atom. Hence, the term for the chlorine ligands is $+(2×2)$ as given by Matthew.

This part of a broader rule in transition-element-complex electron counting. Halogens are to be rendered as halide ion ligands that usually donate two electrons, but add one to the oxidation state of the metal.

$\endgroup$

Not the answer you're looking for? Browse other questions tagged or ask your own question.