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

Which of the following is a pair of paramagnetic complexes?

  1. [W(CO)6] and [Cr(NH3)6]3+

  2. [Co(NH3)6]3+ and [W(CO)6]

  3. [Fe(CN)6]3- and [Co(NH3)6]3+

  4. [Co(NH3)6]3+ and [Cr(NH3)6]3+

  5. [Cr(NH3)6]3+ and [Fe(CN)6]3-
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

[Cr(NH3)6]3+: t2g3 eg0; 3 unpaired electrons; paramagnetic [Fe(CN)6]3-: t2g5 eg0; one unpaired electron; paramagnetic

Multiple choice

Geometrical isomerism is exhibited by

  1. [Zn(NH3)2Cl2]

  2. [Co(NH3)6]3+

  3. [Pt(NH3)2Cl2]

  4. [Ni(CN)4]2-

  5. All of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

[Pt(NH3)2Cl2] is a heteroleptic square planar complex of Ma2b2 type. In a square planar complex of formula [Ma2b2], the two similar ligands may be arranged adjacent to each other in a cis isomer or opposite to each other in a trans isomer.

Multiple choice

Which of the following statements is incorrect?

  1. [Mn(CN)6]3-, [Fe(CN)6]3- and [Co(C2O4)3]3- are diamagnetic inner orbital complexes that involve d2sp3 hybridisation.

  2. The ligand field strength increases in the order SCN- < C2O42- < NCS- < en < CO.

  3. [Mn2(CO)10] has one Mn-Mn bond and [Co2(CO)8] has one Co-Co bond.

  4. [MnCl6]3-, [FeF6]3- and [CoF6]3- are paramagnetic outer orbital complexes that involve sp3d2 hybridisation.

  5. M-C bond length in [Fe(CN)6]3- is lower than that in [Mn(CN)6]3-.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Correct Answer: [Mn(CN)6]3-, [Fe(CN)6]3- and [Co(C2O4)3]3- are diamagnetic inner orbital complexes that involve d2sp3 hybridisation.

Multiple choice

Primary valency of iron in K4 [Fe (CN)6] is

  1. 2

  2. 3

  3. 4

  4. 5
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In K4[Fe(CN)6], the primary valency corresponds to the oxidation state of the central metal ion. Since the total charge of the complex is 0 and CN is -1, Fe + 6(-1) = -4, so Fe = +2.

Multiple choice

Which of the following is non-ionisable?

  1. [CO (NH3)6] Cl3

  2. [CO (NH3)3 Cl3]

  3. [CO (NH3)4 Cl2] Cl

  4. [CO (NH3)5 Cl] Cl2
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A complex is non-ionisable if there are no counter-ions outside the coordination sphere. In [CO(NH3)3Cl3], all ligands are inside the coordination sphere, so it does not ionize in water.

Multiple choice

Which of the following will not show geometrical isomerism?

  1. [Pt (NH3)2Cl2]

  2. [CO (en)2 Cl2] Cl

  3. [Cr (NH3)4Cl2] Cl

  4. [CO (NH3)5 NO2] Cl2
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Geometrical isomerism requires different spatial arrangements of ligands. [CO(NH3)5NO2]Cl2 is an octahedral complex where all positions are occupied by NH3 or NO2, and it does not allow for cis/trans arrangements that result in distinct isomers.

Multiple choice

Which is not a p bonded complex?

  1. Zeise's salt

  2. Ferrocene

  3. tetra ethyl lead

  4. dibenzene chromium
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Pi-bonded organometallic complexes involve pi-electron systems (like alkenes or aromatic rings) donating to the metal. Tetraethyl lead is a sigma-bonded organometallic compound.