The d-electron configurations of `Cr^(2+), Mn^(2+), Fe^(2+)` and `Co^(2+)` are `d^4, d^5, d^6` and `d^7` respectively. Which one of the following will exhibit minimum paramagnetic behavious?

Options

A. `[Cr(H_(2)O)_(6)]^(2+)`
B. `[Mn(H_(2)O)_(6)]^(2+)`
C. `[Fe(H_(2)O)_(6)]^(2+)`
D. `[Co(H_(2)O)_(6)]^(3+)`

Answer

D

Explanation

Because `H_(2)O` is a weak field ligand, all these complexes are high spin complexes. Such complexes always have the same number of unaired electrons on the metal atom/ion as when the metal is uncomplxed: