How to Find the Roman Numeral

[Frederick Keith_4C]

I already asked what the roman numeral represents, but this time I'm asking how do you find it?
For example, if the compound was [Co (NH)3 (H2O)3]2 (SO4^-2)3 what would the name and roman numeral be?

[DarrenKim_1H]

So that coordination compound is shown to be neutral. So you would find the net negative charge of 3 So4^2-, which is -6 (3 times -2). In the cation, NH3 and H2O are both neutral so Cobalt is the only component that has a charge which is +3.
Overall, its a net positive charge of +6 since (2 times 3 = 6).

Therefore, the whole compound is neutral. (6-6 = 0 charge)

[Matt F]

Typically you want to find it by process of elimination. See what the overall charge of the coordination compound is, and then determine what components inside are that make it up. From there, the roman numeral will take on whatever value it needs to be so that the components equal the total charge. Hope this helps!

[Maddie]

so is it usually the charge found for the transition metal

[Amy Kumar 1I]

Work backwards from the overall charge and charge of the ligands to find the charge on the metal.