Question

The correct IUPAC name of the complex [Pt(NH$_3$)$_2$Cl$_2$] is:

• A. diamminedichloridoplatinum (IV)
• B. diamminedichloridoplatinum (II)
• C. dichloridodiammineplatinum (IV)
• D. dichloridodiammineplatinum (II)

Hint:

In coordination nomenclature: ammine (NH$_3$), aqua (H$_2$O), chlorido (Cl$^-$). Always write ligands alphabetically and include oxidation state of metal.

Answer 1

The Correct Option is B

Concept: Rules for IUPAC naming of coordination compounds:

• Name ligands alphabetically before the metal.
• Neutral ligands: NH$_3$ = ammine.
• Anionic ligands: Cl$^-$ = chlorido.
• Oxidation state of metal is written in Roman numerals.

Step 1: Identify ligands. NH$_3$ → ammine (neutral ligand) Cl$^-$ → chlorido (anionic ligand)
Step 2: Arrange ligands alphabetically. Ammine (a) comes before chlorido (c). So, name begins with: \[ \text{diammine dichlorido} \]
Step 3: Find oxidation state of Pt. Let oxidation state of Pt = $x$ NH$_3$ is neutral, Cl = $-1$ \[ x + 2(0) + 2(-1) = 0 \] \[ x - 2 = 0 \Rightarrow x = +2 \]
Step 4: Write final IUPAC name. \[ \text{diamminedichloridoplatinum (II)} \]