Chemistry

Coordination Chemistry

319 Questions

Coordination chemistry focuses on coordination compounds, their structures, and their magnetic properties. The questions cover primary and secondary valencies, ligand types, and geometries of complexes. This topic is heavily tested in chemistry competitive exams and requires a good grasp of molecular structures.

primary and secondary valencycomplex geometriesligand field theorymagnetic properties of complexesisomerism in complexes

Coordination Chemistry Questions

Multiple choice

The magnetic moment of an octahedral Co(II) complex is 4.0 BM. The electronic configuration of the central metal ions is

  1. 5t2g, 2eg

  2. 6t2g , 1eg

  3. 3t2g, 4eg

  4. 4t2g, -3eg

  5. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

This option is correct, because the Co(II) octahedral complex has 4.0 BM magnetic moment when the Co(II) act as the high spin in nature. Therefore 3 unpaired electrons contribute in t2g and one unpaired electron in eg set. Therefore the magnetic moment  is 4.0 BM.

Multiple choice

The pair of ion that forms complex with coordination number 2 is

  1. Cd(II) and Hg(II)

  2. Cu(II) and Hg(II)

  3. Cd(II) and Hg(I)

  4. Cu(I) and Hg(II)

  5. None of these
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

This option is correct, because the Cu(I) and Hg(II) metals ions act as the minimum repulsion in between ligand to formed linear geometry of the complex.

Multiple choice

Regarding the two complexes - (A) - [Ni(H2O)6]++ and (B) - [Ni(NH3)6]++, which of the following statement is correct?

  1. Complex (A) is diamagnetic and complex (B) is paramagnetic

  2. Complex (A) is paramagnetic and (B) is diamagnetic.

  3. Both paramagnetic

  4. Both are diamagnetic

  5. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

This option is correct,  because in the both complexes ion Ni(28) is present as Ni++ ions. The Ni atom has valence shell configuration 3d84s2 but Ni++ ions indicate 3d8configuration. The magnetic measurement is complex of the ions paramagnetic it has two unpaired electron. They act as high spin in nature  and it gives rise to sp3d2 hybridization.

Multiple choice

For [Ti(H2O)6]3+ maximum absorption is due to d-d transition found at 20000 cm-1. Calculate the crystal field stabilization energy for the complex ions.
    • 20000 cm-1

  2. 4/9 x 20000 cm-1

  3. 8000 cm-1
    • 8000 cm-1

  5. None of these
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

This option is correct, because the octahedral high spin complex Ti exhibits trivalent state. It belongs to the 3d1 orbital which split in to t2g and eg set. The electron is istributed in 1t2g and 0eg. Hence,  CFES = [- 0.4p + 0.6q] Dq + mP, here p = Number of electron in t2g, q = Number of electron in eg, set Dq = 20000 cm-1 m = Number of paired electron, mean pairing energy. Calculation - [- 0.4 x 1 + 0.6 x 0] 20000 cm-1 + 0 = - 0.4 x 20000 cm-1 = - 8000 cm-1

Multiple choice

Arrange the following transition metal ions in increasing order of their magnetic moments.

  1. Ti2+
  2. V2+
  3. Cr2+
  4. Mn2+ Select the correct answer using the codes given below:

  1. 1 < 2 < 3 < 4

  2. 1 < 3 < 2 < 4

  3. 2 < 1 < 4 < 3

  4. 3 < 2 < 4 < 1

  5. 4 < 3 < 2 < 1
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The magnetic moment increases with increasing number of unpaired electrons. Ti2+: [Ar] 3d2; 2 unpaired electrons V2+ : [Ar] 3d3; 3 unpaired electrons Cr2+: [Ar] 3d4; 4 unpaired electrons Mn2+: [Ar] 3d5; 5 unpaired electrons Hence, the correct order of magnetic moment is Ti2+ < V2+ < Cr2+ < Mn2+.

Multiple choice

Among the following the more stable complexes of thalium is/are

P. Tl(OH) Q. TlCl3 R. TlBr S. TlN3

  1. P only

  2. Q only

  3. R only

  4. P and Q

  5. Q and R
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Thallium tends to oxidize to the +3 and +1 oxidation states as ionic salts. The +3 state resembles that of the other elements in thallium's group (boron, aluminum, gallium, indium). Thallium represents +1 oxidation state due to the inert pair effect. Hence, Tl(OH) and TlBr are more stable complexes than TlN3 and TlCl3.

Multiple choice

Which of the following pairs is not correctly matched?

  1. Ethylene diaminetetraacetate ion: Hexadentate ligand

  2. Chemotherapy of cancer: cis-[PtII (NH3)2 Cl2]

  3. Cyanate ion: Ambidentate ligand

  4. Nitrite ion: Bidentate ligand

  5. Pentaamminechloridocobalt(III) sulphate: [Co(NH3)5Cl]SO4
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The nitrite ion (NO2-) is an ambidentate ligand and can bind to metal ions through either the nitrogen or oxygen atom.