Question

The IUPAC name of $\left[\mathrm{Co}{\left({\mathrm{NH}}_3\right)}_4\left({\mathrm{H}}_2\mathrm{O}\right)\mathrm{Cl}\right]{\mathrm{Cl}}_2$

Answer 1

IUPAC rules for the naming of Coordination compounds:

• Coordination compounds contain a metal ion and ligand attached to the metal ion, where the ligands donate their electron pair to the metal center.
• For naming a coordination compound, first, hen the ligand name that is attached to the metal center should be written.
• If two ligands are present, they should be written in alphabetical order.
• Then the metal ion name should be written along with their oxidation state.
• A suitable prefix should be used before the ligand name if it is present more than one time if three-tri is used etc.
• The ligand outside the bracket should be written independently at the last.
• As a separate word, write ion if it is not neutral if negative charge is over the sphere use suffix -ate.

$\left[\mathrm{Co}{\left({\mathrm{NH}}_3\right)}_4\left({\mathrm{H}}_2\mathrm{O}\right)\mathrm{Cl}\right]{\mathrm{Cl}}_2$:

Step 1: Finding central metal ion:

• The central metal ion present in the compound $\left[\mathrm{Co}{\left({\mathrm{NH}}_3\right)}_4\left({\mathrm{H}}_2\mathrm{O}\right)\mathrm{Cl}\right]{\mathrm{Cl}}_2$ is cobalt.

Step 2: Identifying ligands present in the compound and their naming:

• The ligands present in these compounds are ammine $\left({\mathrm{NH}}_3\right)$, aqua $\left({\mathrm{H}}_2\mathrm{O}\right)$and chloride $\left(\mathrm{Cl}\right)$.
• There is four amine ligand so tetraamine is first written and then water is present its IUPAC name is aqua and chloride is written.
• As amine ligand is first in alphabetic order then the aqua and then the chloride so it is written in that way.

Step 3: Finding the oxidation state of the central metal atom and outer sphere ion naming.

• The oxidation state of cobalt is $+3$, as amine and aqua are neutral ligands it does not give this oxidation number, the oxidation number comes from three chloride ligands that are present in it. The oxidation state should be mentioned in roman numerals.
• The outer sphere ion present here is chloride.
• So, the IUPAC name of this compound is $\mathrm{Tetraammineaquachloro}\mathrm{cobalt}\left(\mathrm{III}\right)\mathrm{chloride}$.