question_answer 48)

What can be inferred from the magnetic moment of the following complex species Example              Magnetic moment (BM) K4[Mn(CN)6]                      2.2 [Fe(H2O)6]2+                       5.3 K2 [MnCl4]                           5.9

Answer:

Magnetic moment When n =1, = When n = 2, When n = 3, When n = 4,p = When n = 5, (i) . In this complex Mn is in +2 oxidation state, (Mn2+ ) = 2.2 BM suggests that it has only one unpaired electron. Thus, when CN? ligands approach Mn2+ ion, the electrons in 3d subshell pair up as shown in Fig. (a) Thus, CN? is a strong ligand.         d2 sp3hybridisation is involved and the complex is inner orbital octahedral complex. (ii) [Fe(H2O)6]2+. In this complex, Fe is in + 2 state (Fe2+). BM suggests that there are four unpaired electrons. This means that the electrons in 3d do not pair up when the ligands, H2O molecules, approach. Thus, H2O is a weak ligand. To accommodate the electrons donated by the H2O molecules, the hybridization involved will be sp3d2. Hence, is will be outer orbital octahedral complex. (iii) K2[MnCl4]. In this complex, Mn is in in + 2 state (Mn2+)  BM suggests that there are five unpaired electrons. The hybridization is sp3 and the complex has tetrahedral geometry.