Question

The IUPAC name of $\left[ \text{Co}{{\left( \text{N}{{\text{H}}_{3}} \right)}_{6}} \right]\text{C}{{\text{l}}_{3}}$ is hexammine cobalt $\left( \text{III} \right)$ chloride.
A. True
B. False

Answer 1

First understand the compound structure and functional groups attached to it; by it we can determine the IUPAC name. To name any compound, there are certain sets of rules to be followed to write IUPAC names. Write the name along with the rules.

Complete step by step answer:
- First find the oxidation state of central metal atom $\text{Co}$ in $\left[ \text{Co}{{\left( \text{N}{{\text{H}}_{3}} \right)}_{6}} \right]\text{C}{{\text{l}}_{3}}$. The compound has six ligands.
Let the oxidation state of $\text{Co}$ be x. The charge on chloride ions is 1. The overall charge on the compound is 0. The charge on ammonia ligands is 0.
Hence, the oxidation will be $\left[ \text{x}+\left( 0\times 6 \right) \right]+\left( 3\times -1 \right)=0$ ; so x equals to +3. The oxidation state of $\text{Co}$ is +3.
The oxidation state while writing IUPAC name is written in roman numerals inside brackets.
- If anions are present outside the parentheses, then anion is mentioned after the oxidation state of the central metal atom. The name of anion is written, the number of anions is not mentioned. The name of chlorine anion is chloride.
The number of cobalt atoms is 1, so the name of $\text{Co}$ will be cobalt.
The number of ammonia atoms is 6, so the name will be ‘hexammine’. The IUPAC name is written in alphabetical order.
The IUPAC name of $\left[ \text{Co}{{\left( \text{N}{{\text{H}}_{3}} \right)}_{6}} \right]\text{C}{{\text{l}}_{3}}$will be hexammine cobalt $\left( \text{III} \right)$ chloride. The

correct answer is option ‘a’ as it is a true statement.

Additional Information: Other name of $\left[ \text{Co}{{\left( \text{N}{{\text{H}}_{3}} \right)}_{6}} \right]\text{C}{{\text{l}}_{3}}$ are cobalt hexammine chloride and hexamminecobalt $\left( \text{III} \right)$ chloride.
The compound is useful in DNA condensation studies. It is capable of activating enzymes that require magnesium.

Note: The name of the compound is written with substituents in alphabetical order followed by its base name. Between numbers, commas are used and dashes are used between letters and numbers.