Naming Coordination Compounds

[Patrick Wilson 2B]

When naming a coordination compound how can you determine the oxidation state of the metal? For example how would we tell if it is Copper(II) or Copper(III)?

[Ricardo Munoz 3K]

Good question!
Basically, you need to see how many other ligands are bound to the central atom (the transition metal), and see if anyone of them has a negative charge. For example, if you have the ion [CoCl3]-, you see that there are three Cl- ions. Therefore, they all have an overall charge of 3-. However, the ion itself has a charge of 1-. Therefore, you can see that the cobalt would need to have a charge of 2+ to cancel out part of the charge from the Cl- ions. Thus, it would be cobalt (II). If the coordination compound were [CoCl3], Co would have a charge of 3+, since the negative ions were cancelled out; thus, cobalt (III).
I hope my explanation helped!

[michaeljwilson3]

when given the name of a compound, how do you know the order in which each element goes in the molecular formula?

[Chem_Mod]

Write the transition metal first after the first square bracket, but for this class, the order of the ligands doesn't matter when writing the formula. When given the formula and asked to name the complex, however, name the ligands in alphabetical order.

[Morgan Zapasnik 1N]

I have a quick follow up question about naming coordination compounds!
How do we know when to use the latin name of certain metals vs when to just use their normal names?
For example, when is iron called ferrate?
Thanks in advance!

[Diana Catapusan 1N]

I think you would use ferrate instead of iron when the iron atom has an overall negative charge. For example, when the overall compound that includes an iron atom is negative, you wouldn't change it to "ironate," you would change it to ferrate. There are a few other metals, like copper, that also change names. At a review session, a UA said that we might not be responsible to know all the exceptions because we have not covered those name changes in class, but I would double check on that. Hope this helps!