JEE Chemistry 2024 Question with Solution

Given: The complex is $[\text{Pt(NH}_3\text{)}_2\text{Cl(NH}_2\text{CH}_3\text{)}]\text{Cl}$ and it is square planar.

Find: The spin-only magnetic moment in B.M.

The square planar complex $[\text{Pt(NH}_3\text{)}_2\text{Cl(NH}_2\text{CH}_3\text{)}]\text{Cl}$ involves a Pt(II) center. For Pt(II), we remove two electrons from the neutral Pt atom, which has the electronic configuration:

Removing two electrons gives:

In a square planar complex with a $d^8$ configuration, all electrons are paired due to strong field ligands causing large splitting, which leaves the complex diamagnetic.

The spin-only magnetic moment $\mu_s$ is given by

where $n$ is the number of unpaired electrons.

Since the complex is diamagnetic, $n = 0$. Therefore,

So, the nearest integer value is $0$.

Given: $\text{Pt}^{2+}$ is present in a square planar complex.

Find: Number of unpaired electrons and hence the magnetic moment.

$\text{Pt}^{2+}$ has a $d^8$ electronic configuration. In square planar complexes, the $d$-electrons pair up in such a way that no unpaired electrons remain.

As a result, the complex is diamagnetic and its magnetic moment is

Therefore, the correct answer is $0$.