Q.47 Using valence bond theory, explain the following in relation to the complexes given below

Mn(CN63-,Co(NH3)63+,Cr(H20)63+,FeCl64-

(a) Type of hybridisation 

(b) lnner or outer robital comples

(c) Magnetic behaviour

(d) Spin only magnetic moment value.


Mn(CN)63-

(i) d2sp3 hybridisation 

(ii) lnner orbital complex because (n-1)d-orbitals are used.

(iii) Paramagnetic, as two unpaired electons are present. 

(iv) Spin only magnetic moment (μ)=2(2+2)=8=2.82 BM

(b) Co(NH3)63+Co3+=3d64s0

(NH3 pair up the unpaired 3d electons)

(i) d2sp3 hybridisation 

(ii) lnner orbital complex because of the invovement of *n-1) d-orbital in bonding.

(iii) Diamagnetic, as no unpaired electron is preset.

(iv) μ=n(n+2)=0(0+2)=0 (Zero)

(c) Cr(H2O63+

(i) d2sp3 hybridisation 

(ii) lnner orbital complex (as(n-1) d-orbital take part)

(iii) Paramagnetic (as three unpaired electrons are present 

(iv) μ=n(n+2)=3(3+2) =15=3.87 BM

(d) Fe(Cl)64-Fe2+=3d6

(i) sp3d2 hybridisation

(ii) Outer orbital complex because nd-orbitals are involved in hybridisation.

(iii) Paramagnetic (because of the presence of four unpaired electrons).

(iv) μ=n((n+2)=4(4+2)=24=4.9BM