Question

The electronic configurations of Cr²⁺ , Mn²⁺ , Fe²⁺ and Ni²⁺ are 3d⁴ , 3d⁵ , 3d⁶ and 3d⁸ respectively. Which one of the following aqua complexes will exhibit the minimum paramagnetic behaviour?

(a) [Mn(H₂O)₆]²⁺

(b) [Fe(H₂O)₆]²⁺

(c) [Ni(H₂O)₆]²⁺

(d) [Cr(H₂O)₆]²⁺

Answer 1

Correct option: (c) [Ni(H₂O)₆]²⁺

The electronic configurations of Ni²⁺ is 3d⁸ .

Electronic configuration of Cr2+ is 3d4 .

Electronic configuration of Mn2+ is 3d5 .

Electronic configuration of Fe2+ is 3d6 .

Number of unpaired electrons is minimum in [Ni(H₂O)₆]²⁺, thus it show minimum paramagnetic behaviour.