Identify the metal ions among Co2+, Ni2+, Fe2+, V3+ and Ti2+ having a spin-only magnetic moment value more than 3.0 BM. The sum of unpaired electrons present in the high spin octahedral complexes formed by those metal ions is .
Answer
7
Solution
= n(n+2) BM; > 3.0 BM needs n 3 (n = 2 gives 2.83 BM)
Co2+: 3d7 ⇒ n = 3, = 3.87 BM
Ni2+: 3d8 ⇒ n = 2, = 2.83 BM
Fe2+: 3d6 ⇒ n = 4, = 4.90 BM
V3+: 3d2 ⇒ n = 2, = 2.83 BM
Ti2+: 3d2 ⇒ n = 2, = 2.83 BM
Ions with > 3.0 BM: Co2+ and Fe2+
High spin octahedral (weak field):
Co2+ ( t2g5 eg2) ⇒ 3 unpaired electrons
Fe2+ ( t2g4 eg2) ⇒ 4 unpaired electrons
Sum = 3 + 4 = 7
Answer: 7