Question

Write the geometrical isomers of [PtCl₂(NH₃)₂].

Answer 1

The complex [PtCl₂(NH₃)₂] is a square planar coordination compound, and it exhibits geometrical isomerism due to the different possible spatial arrangements of the two chloride ions (Cl) and two ammonia molecules (NH₃) around the platinum (Pt) centre.

1. Cis  isomer - The two Cl ions are adjacent to each other (90°).
   \[\begin{array}{cc}
   \phantom{.}\ce{NH3}\phantom{.}\ce{Cl}\\
   \backslash\phantom{..}/\\
   \ce{Pt}\\
   /\phantom{..}\backslash\\
   \phantom{..}\ce{NH3}\phantom{.}\ce{Cl}\phantom{.}
   \end{array}\]
2. Trans isomer - The two Cl ions are opposite each other (180°).
   \[\begin{array}{cc}
   \phantom{.}\ce{NH3}\phantom{.}\ce{Cl}\\
   \backslash\phantom{..}/\\
   \ce{Pt}\\
   /\phantom{..}\backslash\\
   \phantom{..}\ce{Cl}\phantom{.}\ce{NH3}\phantom{.}
   \end{array}\]