This apparent
anomaly is explained by valence bond theory in terms of formation of
inner orbital and outer orbital coordination entities [Mn(CN)6]
3–, [Fe(CN)6]
3–
and [Co(C2O4)3]
3– are inner orbital complexes involving d
2sp
3 hybridisation,
the former two complexes are paramagnetic and the latter diamagnetic On the other hand, [MnCl6]
3–, [FeF6]
3– and [CoF6-]
3– are outer orbital
complexes involving sp
3d
2
 hybridisation and are paramagnetic
corresponding to four, five and four unpaired electrons Rationalised 2023-24
131
Coordination Compounds
The spin only magnetic moment of [MnBr4]
2– is 5