Statement I: All inner orbital complexes are diamagnetic

Statement II: Inner orbital complexes may or may not contain unpaired electrons

Statement I is false but Statement II is correct

The correct answer is option 4. Statement I is false but Statement II is correct.

Let us delve into each statement regarding inner orbital complexes:

Statement I: All inner orbital complexes are diamagnetic.

This statement is false. Inner orbital complexes can exhibit either diamagnetic or paramagnetic properties depending on the number of unpaired electrons in the d orbitals of the central metal ion.

Diamagnetic Complexes: These complexes have all d electrons paired, resulting in a net magnetic moment of zero. Examples include \([Ni(CN)_4]^{2-}\) where Ni(II) has a \(d^8\) configuration, all electrons are paired, and the complex is diamagnetic.

Paramagnetic Complexes: These complexes have one or more unpaired d electrons, resulting in a net magnetic moment. For instance, \([Fe(H_2O)_6]^{3+}\) has a \(d^5\) configuration with five unpaired electrons, making it paramagnetic.

Statement II: Inner orbital complexes may or may not contain unpaired electrons.

This statement is true. The presence of unpaired electrons in inner orbital complexes depends on several factors:

Oxidation State: Different oxidation states of the metal ion can lead to different numbers of unpaired electrons.

Ligand Field Splitting: The splitting of d orbitals in the presence of ligands can affect whether the electrons remain paired or unpaired.

Electronic Configuration: The distribution of electrons among the d orbitals, influenced by ligand field and oxidation state, determines the magnetic properties.

Relationship Between the Statements

Statement II correctly explains why Statement I is false. Inner orbital complexes can have unpaired electrons, which makes them paramagnetic rather than diamagnetic.

Paramagnetic Examples: Complexes like \([Fe(H_2O)_6]^{3+}\) (\(d^5\) configuration) are paramagnetic due to their unpaired electrons despite being inner orbital complexes.

In summary:

Statement I is false because inner orbital complexes can be paramagnetic if they contain unpaired electrons. Statement II is correct because inner orbital complexes can indeed have varying numbers of unpaired electrons depending on their electronic configuration and ligand environment. Therefore, the correct assessment is: Statement I is false but Statement II is correct.