Roman Numeral

[Maritza Jacobo]

Hey, how do you know what numeral number each compound has? Do you look at the ligand's charge? Thanks!

[Averie Moore 2F]

The metal ion has to balance the overall charge.
metal ion charge = total ligand charge + charge of the coordination complex

[105561735]

The overall charge has to be balanced in order to come about with the roman numeral.

[105561735]

I found this video to be a bit helpful when trying to understand how to come about with the roman numerals

https://youtu.be/r4H5XjJPn58?si=PiwgmVjRHQHBaeUX

[Holiday Parsons 2D]

if we look at hexacyanoferrate(III) ([Fe(CN)₆]³^-), we can see that the roman numeral is III. This is referring to the charge of the iron atom. We know this because the charge of the CN ligands are 6- because the charge of CN is -1 and we have 6 of them. Since we have an overall charge of 3- then we need that Fe to have a charge of 3+. This means that the roman numeral is determined by the oxidation state of the central metal atom. So yes, we basically have to determine the charges of the other ligands and pay attention to the overall charge of the complex to determine the charge of the central atom and thus identify the roman numeral we'll add to the complex name.