Question

The IUPAC name for the complex \( [\text{Co}(\text{ONO})(\text{NH}_3)_5]\text{Cl}_2 \) is

• A. \( Pentaammine-nitrito-O-cobalt(II) chloride \)
• B. \( Pentaammine-nitrito-O-cobalt(III) chloride \)
• C. \( Nitrito-N-pentaamminecobalt(III) chloride \)
• D. \( Nitrito-N-pentaamminecobalt(II) chloride \)

Hint:

When naming coordination compounds, make sure to specify the donor atom (either \( O \) or \( N \)) for ambidentate ligands like \( \text{ONO} \) to avoid confusion.

Answer 1

The Correct Option is B

The complex \( [\text{Co}(\text{ONO})(\text{NH}_3)_5]\text{Cl}_2 \) comprises:
\( \text{ONO} \): A nitrito ligand coordinated through oxygen (nitrito-O),
\( \text{NH}_3 \): Five neutral ammine ligands,
\( \text{Cl}_2 \): Two chloride counter ions.
The oxidation state of cobalt is calculated as follows:
\[\text{Co} + 5(0) + (-1) + 2(-1) = 0 \implies \text{Co} = +3.\] Thus, the IUPAC name is: \[\boxed{\text{Pentaammine-nitrito-O-cobalt(III) chloride}}.\]