Question

The IUPAC name of the complex \([Co(NH_3)_5ONO]Cl_2\) is}

• A. Pentaamminenitritocobalt (III) chloride
• B. Pentaamminenitritocobalt (II) chloride
• C. Pentaamminenitrocobalt (III) chloride
• D. O-Nitritopentaamminecobalt (III) chloride
• E. Pentaamminemononitritocobalt (III) chloride

Hint:

For coordination compounds:

• first find oxidation state of metal,
• then name ligands in alphabetical order,
• and finally write metal with oxidation state in Roman numerals.

Answer 1

The Correct Option is A

The complex is: \[ [Co(NH_3)_5ONO]Cl_2 \] Outside the bracket there are 2 chloride ions, so the complex cation has charge \(+2\). Now calculate oxidation state of cobalt: \[ x + 0 + (-1)=+2 \] \[ x-1=2 \Rightarrow x=+3 \] So cobalt is in the +3 oxidation state. The ligand \(ONO\) is nitrito. Thus the name is: \[ \text{Pentaamminenitritocobalt (III) chloride} \]
Hence, the correct answer is: \[ \boxed{(A)} \]