Among the species given below, the spin-only magnetic moment is highest for (Given: Atomic number of Ti = 22, Mn = 25, Fe = 26 and Co = 27)
- [Ti(H2O)6]3+
- [Mn(CN)6]3-
- [Fe(CN)6]3-
- [Co(NH3)6]3+
Answer
(2) [Mn(CN)6]3-
Solution
1. [Ti(H2O)6]3+: Ti3+ (3d1), number of unpaired electrons n = 1, = 1(1+2) = 1.73 BM.
2. [Mn(CN)6]3-: Mn3+ (3d4), strong field ligand CN- causes pairing to give t2g4 eg0, n = 2, = 2(2+2) = 8 2.83 BM.
3. [Fe(CN)6]3-: Fe3+ (3d5), strong field ligand CN- gives t2g5 eg0, n = 1, = 1.73 BM.
4. [Co(NH3)6]3+: Co3+ (3d6), strong field ligand NH3 gives t2g6 eg0, n = 0, = 0.
Hence, [Mn(CN)6]3- has the highest spin-only magnetic moment. Answer: (2)