Q. What Numerical prefixes indicate in ligands?

In any complex species, the ligands are quoted in alphabetical order, without regard to charge, before the name of the central metal atom. Numerical prefixes indicating the number of ligands are not considered in determining that order. For example, a compound like [CoCI (NO₂) (en) ₂] CI will be called chlorobis (ethylenediamine) nitrocobalt(J11) chloride.

The oxidation state of the metal ion in a complex is indicated by Roman (I), (II),.(III)  etc. or an Arabic (0) and placed in parenthesis immediately after the name of the metal If, however, the complex species is an anion, the oxidation state of the metal is  mentioned at the end of the name of the complex.