Q.

Match List I with List II                    [2025]

  List-I   List-II
  (Complex)   (Hybridisation & Magnetic characters)
(A) [MnBr4]2- (I) d2sp3 & diamagnetic
(B) [FeF6]3- (II) sp3d2 & paramagnetic
(C) [Co(C2O4)3]3- (III) sp3& diamagnetic
(D) [Ni(CO)4] (IV) sp3 & paramagnetic

 

Choose the correct answer from the options given below:

1 (A)-(III), (B)-(I), (C)-(II), (D)-(IV)  
2 (A)-(IV), (B)-(II), (C)-(I), (D)-(III)  
3 (A)-(IV), (B)-(II), (C)-(III), (D)-(I)  
4 (A)-(I), (B)-(II), (C)-(IV), (D)-(III)  

Ans.

(2)

(A)  [MnBr4]2-

Oxidation number of Mn = +2

Mn2+=[Ar]183d5

For coordination number 4 as in given complex, possible shapes are square planar (with dsp2 hybridization) or tetrahedral (with sp3 hybridization). For dsp2 hybridization, electrons in 3d orbital need to pair up to make one d orbital vacant. But since bromide is a weak field ligand, it cannot cause pairing.

So this is sp3 hybridized and paramagnetic.

(B) [FeF6]3-

Oxidation number of Fe = +3

F- is a weak field ligand. It cannot pair up d electrons. Thus 4d orbitals are used for sp3d2 hybridization. Six e- pairs from six F- are accommodated in these six sp3d2 orbitals.

As it has unpaired electrons, it is paramagnetic.

(C) [Co(C2O4)3]3-

Oxidation number of Co = +3

Co3+=[Ar]183d6

With Co3+, in octahedral complexes, C2O42- and H2O act as strong field ligands.

As all electrons are paired, it is diamagnetic.

(D) [Ni(CO)4]

Oxidation number of Ni = 0

Ni28=[Ar]183d84s2

CO is a strong field ligand. It shifts 4s electrons to 3d orbital to give 3d10 configuration. 

4s orbital becomes vacant. Ni then undergoes sp3 hybridization and lone pairs from CO are accommodated in sp3 orbitals.

As all electrons are paired, it is diamagnetic. As hybridization is sp3, it is tetrahedral.