The Fe³⁺ ion forms two octahedral complexes, Complex I and Complex II, with two different ligands. Complex I is an inner orbital complex, whereas Complex II is an outer orbital complex. The spin-only magnetic moments (in BM) of Complex I and Complex II are, respectively:

Step-by-step solution

The central metal ion is Fe³⁺ , which has the electronic configuration [Ar] 3d^5 . For Complex I (inner orbital complex), the ligand must be a strong field ligand, which forces the pairing of electrons against Hund's rule. The 3d^5 electrons will occupy the t_ 2g orbitals as t_ 2g ^5 e_g^0 . This leaves exactly 1 unpaired electron ( n = 1 ). The spin-only magnetic moment is = n(n+2) = 1(1+2) = 3 1.73 BM. For Complex II (outer orbital complex), the ligand is a weak field ligand, so no forced pairing occurs. The 3d^5