Question

A metal complex having composition CO(en)2Cl₂ Br has been isolated in two forms A and B. (B) reacted with silver nitrate to give a white precipitate readily soluble in ammonium hydroxide. Whereas A gives a pale yellow precipitate. Write the formula of A and B. state the hybridization of CO in each and calculate their spin only magnetic moment.

Answer 1

A metal complex having composition CO(en)2Cl Br has been isolated in two forms A and B. 

1.(B) reacts with silver nitrate to give a white precipitate readily soluble in ammonium hydroxide. This shows (B) has Cl^Θ counter ion. Hence B is [CO(en)₂ Cl Br] Cl form.

2. (A) reacts with silver nitrate to give a pale yellow precipitate. This shows (A) has Br^Θ counter ion. 

Hence A is [CO(en)2Cl₂] Br.

3. Formula of A and B

1. [CO(en)₂Cl₂] Br 

2. [CO(en)₂Cl Br] Cl 

1. A – [CO(en)₂Cl₂] Br

Electronic configuration of CO atom Electronic configuration of CO³⁺ atom Hybridisation and formation of [CO(en)₂Cl₂] Br complex

d² sp³ hybridisation en is strong field ligand. No unpaired electrons, hence it is diamagnetic. Magnetic moment

µs = g\(\sqrt{n(n+2)}\)

n = 0

µ_s = 0

2. A – [CO(en)₂Cl Br] Cl

Electronic configuration of CO atom

Electronic configuration of CO^{3+ atom}

d²sp³ hybridisation en is strong field ligand. No unpaired electrons, hence it is diamagnetic. Magnetic moment,

µ_s = 0

∵n = 0