Question

For octahedral $Mn ( II )$ and tetrahedral $Ni ( II )$ complexes, consider the following statements :
(I) both the complexes can be high spin
(II) Ni(II) complex can very rarely be low spin.
(III) with strong field ligands, $Mn$ (II) complexes can be low spin.
(IV) aqueous solution of $Mn$ (II) ions is yellow in color.
The correct statements are :

• A. (I), (III) and (IV) only
• B. (II), (III) and (IV) only
• C. (I), (II) and (III) only
• D. (I) and (II) only

Answer 1

Answer: (C)

(I) Under weak field ligand, octahedral $Mn ( II )$ and tetrahedral $Ni(II)$ both the complexes are high spin complex.

(II) Tetrahedral $Ni(II)$ complex can very rarely be low spin because square planar (under strong ligand) complexes of $Ni ( II )$ are low spin complexes.

(III) With strong field ligands $Mn (II)$ complexes can be low spin because they have less number of unpaired electron (unpaired electron $=1)$

While with weak field ligands $Mn ( II )$ complexes can be high spin because they have more number of unpaired electron (unpaired electron $=5)$

(IV) Aqueous solution of $Mn ( II )$ ions is pink in colour.