Coordination Compounds — Class 12 Chemistry PYQs

The type of isomerism shown by the complex [CoCl₂(en)₂]⁺ is :
(A) Linkage isomerism
(B) Geometrical isomerism
(C) Coordination isomerism
(D) Ionization isomerism

Ligand EDTA₄– is an example of a :
(A) Monodentate ligand
(B) Didentate ligand
(C) Tridentate ligand
(D) Polydentate ligand

The coordination number of Co in [Co(en)₃]³⁺ is :
(A) 3
(B) 4
(C) 5
(D) 6

Which one of the following hybrid states is associated with low spin complex ?

(A) sp³d
(B) sp³
(C) sp³d²
(D) d²sp³

Which one of the following complexes is non-ionisable ?
(A) [Co(NH₃)₃ Cl₃]
(B) [Co(NH₃)₄ Cl₂] Cl
(C) [Co(NH₃)₅ Cl] Cl₂
(D) [Co(NH₃)₆] Cl₃

Which of the following ligand forms chelate complex ?
(A) C₂O₄²⁻
(B) Cl⁻
(C) NO₂⁻
(D) NH₃

(a) Write the formula for the following coordination compound :
Potassium tetrahydroxidozincate (II)
(b) Arrange the following complexes in the increasing order of conductivity of their solution :
[Cr(NH₃)₅Cl]Cl₂, [Cr(NH₃)₃Cl₃], [Cr(NH₃)₆]Cl₃
(c) Identify the type of isomerism exhibited by the following complexes :
(i) [Co(NH₃)₅NO₂]²⁺
(ii) [Co(en)₃]Cl₃

The Valence Bond Theory (VBT) explains the formation, magnetic behaviour and geometrical shapes of coordination compounds whereas 'The Crystal Field Theory' for coordination compounds is based on the effect of different crystal fields (provided by ligands taken as point charges), on the degeneracy of d-orbital energies of the central metal atom/ion. The splitting of the d-orbitals provides different electronic arrangements in strong and weak crystal fields. The crystal field theory attributes the colour of the coordination compounds to d-d transition of the electron. Coordination compounds find extensive applications in metallurgical processes, analytical and medicinal chemistry.

Answer the following questions :

(a) What is crystal field splitting energy ?

(b) Give reason for the violet colour of the complex [Ti(H₂O)₆]³⁺ on the basis of crystal field theory.

(c) [Cr(NH₃)₆]³⁺ is paramagnetic while [Ni(CN)₄]²⁻ is diamagnetic. Explain why.
[Atomic No. : Cr = 24, Ni = 28]

OR

(c) Explain why [Fe(CN)₆]³⁻ is an inner orbital complex, whereas [Fe(H₂O)₆]³⁺ is an outer orbital complex.
[Atomic No. : Fe = 26]

Answer any five of the following :

(a) How is the crystal field splitting energy for octahedral complex (Δ_o) related to that of tetrahedral complex (Δ_t) ?

(b) Write the IUPAC name of the following complex :
PtCl₂(en)₂₂

(c) Write the geometry and magnetic behaviour of the complex [Ni(CO)₄] on the basis of Valency Bond Theory (VBT).

(d) What type of isomerism is shown by the complex [Co(NH₃)₆][Cr(CN)₆] ?

(e) For the coordination compound on the basis of crystal field theory, write the electronic configuration for d⁴ ion if Δ_o < P. Is the coordination compound a high spin or low spin complex ?

(f) Out of [Co(NH₃)₆]³⁺ and [Co(NH₃)₄Cl₂]⁺, which complex is heteroleptic and why ?

(g) Draw the structures of optical isomers of [PtCl₂(en)₂]²⁺.

Write the formula for the following coordination compound :
Potassium tetrahydroxidozincate (II)