IUPAC Name of Platinum Complex $[Pt(NH_3)_2Cl_2]$ Explained

This explanation details how to determine the IUPAC name for the coordination compound $[Pt(NH_3)_2Cl_2]$. Following the standard rules for naming coordination compounds ensures accurate chemical communication.

Steps to Determine the IUPAC Name

1. Identify Ligands and Metal:
   • The ligands present are ammonia ($NH_3$) and chloride ($Cl$).
   • The central metal atom is Platinum (Pt).
2. Name the Ligands:
   • Ammonia ($NH_3$) is named 'ammine'.
   • Chloride ($Cl^-$) is named 'chloro'.
3. Use Prefixes for Multiple Ligands:
   • Since there are two ammonia ligands, the prefix 'di-' is used, making it 'diammine'.
   • Since there are two chloride ligands, the prefix 'di-' is used, making it 'dichloro'.
4. Order of Ligands:

   Ligands are named in alphabetical order. 'Ammine' comes before 'chloro'. Therefore, the ligand part of the name is 'Diamminedichloro'.

5. Name the Central Metal:

   The central metal is Platinum. Since the complex is neutral (no charge indicated outside the brackets), the metal name 'Platinum' is used directly.

6. Determine the Oxidation State of the Metal:

   The oxidation state of the central metal atom needs to be calculated. Let the oxidation state of Platinum (Pt) be '$x$'.

   The overall charge of the complex is neutral (0).

   The ligands are ammonia ($NH_3$), which has a charge of 0, and chloride ($Cl^-$), which has a charge of -1.

   The calculation is as follows:

   $$ \text{Oxidation State of Pt} + (\text{Number of } NH_3 \times \text{Charge on } NH_3) + (\text{Number of } Cl \times \text{Charge on } Cl) = \text{Overall Charge} $$

   $$ x + (2 \times 0) + (2 \times (-1)) = 0 $$

   $$ x + 0 - 2 = 0 $$

   $$ x = +2 $$

   The oxidation state of Platinum is +2, which is written as (II) in Roman numerals.

7. Combine the Parts:

   Combine the ligand names in alphabetical order, the metal name, and its oxidation state: Diamminedichlorido + platinum + (II).

   The complete IUPAC name is Diamminedichloridoplatinum(II).

Matching with Options

Comparing this derived name with the given options, Option 2 is Diamminedichloridoplatinum (II), which matches our result.