Question

If Ni^2– is replaced by Pt^2– in the complex NiCl₂Br₂] ^2– , which of the following properties are expected to get changed?
A. Geometry
B. Geometrical isomerism
C. Optical isomerism
D. Magnetic properties

• A. A, B and C
• B. B and D
• C. B and C
• D. A, B and D

Answer 1

The Correct Option is D

To determine which properties are expected to change if \text{Ni}^{2-} is replaced by \text{Pt}^{2-} in the complex [\text{NiCl}_2\text{Br}_2]^{2-}, it's essential to analyze the properties affected by the metal center in a complex. The complex contains the ligands Cl and Br, and the change in the central metal atom can significantly affect its properties. Let's analyze each option:

1. Geometry: Nickel (Ni) and platinum (Pt) can have different coordination geometries due to their distinct electronic configurations and size. Nickel commonly forms a square planar geometry if it's in a low spin d⁸ configuration, whereas Pt, which also commonly forms square planar complexes, might influence the stereochemistry depending on the complex formation. Therefore, the geometry could change when Ni is substituted by Pt.
2. Geometrical Isomerism: If the geometry of the complex changes, the possibility of geometrical isomerism might also change. For example, a square planar complex can have cis or trans-isomers when different ligands are involved.
3. Optical Isomerism: Optical isomerism would not be directly affected by the central metal change unless the complex's arrangement leads to chirality. Square planar complexes generally do not exhibit optical isomerism unless there's a tendency for unsymmetrical substitution making it chiral.
4. Magnetic Properties: Magnetic properties depend on the number of unpaired electrons. Nickel and platinum, having different electronic configurations, possess different magnetic properties. Ni is often paramagnetic with unpaired electrons in octahedral configuration, whereas Pt in a square planar complex is often diamagnetic due to the fully paired electron configuration.

Therefore, options A, B, and D are expected to change with the replacement of Ni by Pt. The correct answer is \textbf{A, B and D}.