Q23.88P - Chemistry: Molecular Nature Of Matter And Change

Question

How do the relative magnitudes of E_pairing and  $(∆)$ affect the paramagnetism of a complex?

Step-by-Step Solution

Answer

When weak-field ligands bond with the central metal ion, $E_{\mathrm{pairing}}$ is bigger than $∆$ and the high-spin complexes are created. When strong-field ligands bond with the central metal ion, the E pairing is smaller than $∆$ and the low-spin complexes are created.

Step 1: Paramagnetism’s affect

There are two ways by which it affects magnetic properties.

Step 2: Detailed explanation

There are two ways in which relative sizes of $E_{\mathrm{pairing}}$ and $∆$ affect the magnetic properties of complexes:

- when weak-field ligands bond with the central metal ion, the ${\mathrm{E}}_{\mathrm{pairing}}$ is bigger than $∆$ and the high-spin complexes are created. This process takes less energy for electrons to jump to higher energy  $\left({\mathrm{e}}_g\right)$d orbitals and stay unpaired because weak-field ligands cause small splitting energy.

- when strong-field ligands bond with the central metal ion, the ${\mathrm{E}}_{\mathrm{pairing}}$ is smaller than $∆$ and the low-spin complexes are created. This process takes more energy for electrons to jump to higher energy $e_{g}d$ orbitals than to pair up in the lower energy $\left({\mathrm{t}}_{2g}\right)$d orbitals because strong-field ligands cause big splitting energy.