The correct increasing order of spin-only magnetic moment values of the complex ions [MnBr4]2- (A), [Cu(H2O)6]2+ (B), [Ni(CN)4]2- (C) and [Ni(H2O)6]2+ (D) is :
- A = B < D < C
- C = D < B < A
- C < B < D < A
- A = B < C < D
Answer
(3) C < B < D < A
Solution
= n(n+2) BM (n = unpaired electrons)
A: Mn2+, 3d5, weak field Br- (tetrahedral) n = 5, = 5.92 BM
B: Cu2+, 3d9 n = 1, = 1.73 BM
C: Ni2+, 3d8, strong field CN- (square planar, dsp2) n = 0, = 0
D: Ni2+, 3d8, octahedral n = 2, = 2.83 BM
C < B < D < A
Answer: (3)