Chemistry

Coordination Chemistry

325 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 chemistry coordination chemistry werner's theory werner's theory of coordination compounds coordination compounds

According to Werner's theory the primary valency and secondary valency in complex $[Co(NH _3) _4Cl _2]Cl$ is respectively:

  1. 3,3

  2. 3, 6

  3. 6, 3

  4. 4, 2
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The primary valency is the oxidation state of the metal ion and the coordination number of the metal is the secondary valency of the metal ion. 


The oxidation number of $Co = x + 0 -3 = 0$

                                           $x = 3$

The primary valency is 3 and the secondary valency is 6. Therefore, the correct option is B.

Multiple choice chemistry coordination chemistry werner's theory werner's theory of coordination compounds coordination compounds

According to Werner's theory state which of the following statements are correct:


1. Ligands are connected to the metal ions by covalent bonds
2. Secondary valencies have directional properties
3. Secondary valencies are non-ionisable.

  1. 1, 2, and 3 are correct

  2. 2 and 3 are correct

  3. 1 and 2 are correct

  4. 1 ,2 are correct,and 3 is not correct
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

According to Werner's theory, ligands are attached to the central metal ion by coordinate covalent bonds (secondary valency), these valencies have specific spatial arrangements (directional), and they are non-ionizable.

Multiple choice chemistry coordination chemistry werner's theory werner's theory of coordination compounds coordination compounds

Several octahedral complexes are possible from combinations of $Co^{3+}, Cl^{-}$ and $NH {3}$. The correct statement(s) regarding the octahedral coordination entities having the formula .$[Co(NH _{3}) _{n}Cl _{6 - n}]^{(n - 3)+}$ with $n\geq 3$, is/ are____________.

  1. At most six octahedral complexes are possible

  2. One of the complexes is homoleptic

  3. All the complexes are paramagnetic
  4. Some of the complexes dissociate in water to give $Co^{3+}$ and $Cl^{-}$ ions
Reveal answer Fill a bubble to check yourself
A,B Correct answer
Explanation

$[Co(NH _3) _nCl _{6-n}]^{(n-3)^+}$  $n\ge 3$

For $n=3,n=4,n=5,n=6$
For $n=6\Rightarrow [Co(NH _3) _6]^{3+}=$ is  homopletic due to all 6 same ligands.
For $n=5\Rightarrow [Co(NH _3) _6]^{2+}$
For $n=4\Rightarrow [Co(NH _3) _6]^+=$
For $n=3\Rightarrow [Co(NH _3) _6]$
Only $4$ octahedral complex are possible.
One of them is homoleptic.

Multiple choice chemistry coordination chemistry werner's theory werner's theory of coordination compounds coordination compounds

In the separation of $Cu^{2+}$ and $Cd^{2+}$ in the second group of qualitative analysis of cations, tetraamine copper (ll) sulphate and tetraamine cadmium (ll) sulphate react with KCN to form corresponding cyano complexes. Which of the following pairs of complexes and their relative stability enables the separation of $Cu^{2+}$ and $Cd^{2+}$?

  1. $K _2[Cu(CN) _4]$ is less stable and $K _2[Cd(CN) _4]$ is more stable
  2. $K _3[Cu(CN) _4]$ is more stable and $K _2[Cd(CN) _4]$ is less stable
  3. $K _3[Cu(CN) _4]$ is less stable and $K _2[Cd(CN) _4]$ is more stable
  4. $K _2[Cu(CN) _4]$ is more stable and $K _2[Cd(CN) _4]$ is less stable
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The separation of Cu2+ and Cd2+ relies on the relative stability of their cyano complexes. The copper complex [Cu(CN)4]3- is more stable than the cadmium complex [Cd(CN)4]2-, allowing for selective precipitation or reaction.

Multiple choice chemistry coordination chemistry werner's theory werner's theory of coordination compounds coordination compounds

Primary and secondary valency of platinum in the complex $[Pt(en) _{2}Cl _{2}]$ are:

  1. $4,6$
  2. $2,6$
  3. $4,4$
  4. $2,4$
Reveal answer Fill a bubble to check yourself
B,D Correct answer
Explanation

The Given complex $[Pt(en) _2Cl _2]$ The primary valence is its oxidation number i.e +2 and the secendory valency is its coordination number i.e 6 in this case.(The en ligand is bidentate, and Cl is monodentate).The second possibility  is that compound can exist as $[Pt(en) _2]Cl _2$ and hence the primary valency can also be +2 and  secondary valence is 4. Hence option B and D are correct

Multiple choice chemistry coordination chemistry werner's theory werner's theory of coordination compounds coordination compounds

The number of complexes that can be can be made with varying $NH _3$ ligands to satisfy primary and secondary valencies of platinum are:

Complex; [$PtCl _4\cdot xNH _3$]   

  1. 5

  2. 3

  3. 4

  4. 2
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
The correct answer is 5.
The number of complexes that can be can be made with $PtCl _4\cdot xNH _3$ are :
 
I. $[Pt(NH _3) _6]Cl _4$

II. $[Pt(NH _3) _5Cl]Cl _3$

III. $[Pt(NH _3) _4Cl _2]Cl _2$

IV: $ [Pt(NH _3) _3Cl _3]Cl$

V: $[Pt(NH _3) _2Cl _4]$

Option A is correct.
Multiple choice chemistry solid state classification of crystalline solids classification of solids introduction to solids

Which of the following compounds represent represent a normal $2 : 3$ spinel structure?

  1. $Mg^{II} Al _{2}^{III}O _{4}$
  2. $Co^{II} (Co^{III}) _{2}O _{4}$
  3. $Zn(TiZn) O _{4}$
  4. $Ni(CO) _{4}$
Reveal answer Fill a bubble to check yourself
A,B Correct answer
Explanation

In $2:3$ spinel structure                                        General formula is $A^{+2}B _2^{+3}O _4$

$A^{+2} : \cfrac {1}{8}\times Tetrahedral\quad  voids$                    $B^{+3} : \cfrac {1}{2} \times Octahedral\quad voids$        $O^{2-}:FCC\quad lattice$

Only $Mg^{+2}Al _2^{+3}O _4$  and  $Co^{2+}(Co^{3+}) _2O _4$ satisfies the above conditions.

$\longrightarrow$ Also, in option (C) $Ti$ have $+4$ oxidtion state.

Ans-(A), (B)

Multiple choice

Which of the following is an example of a coordination complex?

  1. Sodium chloride

  2. Water

  3. Hemoglobin

  4. Carbon dioxide
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Hemoglobin is a coordination complex, where an iron ion is surrounded by a porphyrin ring and other ligands.

Multiple choice

What is the role of a ligand in an organometallic compound?

  1. To donate electrons to the metal center.

  2. To accept electrons from the metal center.

  3. To stabilize the metal center.

  4. All of the above.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Ligands donate electrons to the metal center, accept electrons from the metal center, and stabilize the metal center.

Multiple choice

Which library is designed for electronic structure calculations using the density matrix renormalization group (DMRG) method?

  1. Psi4

  2. Turbomole

  3. NWChem

  4. ALPS
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

ALPS (Algorithms and Libraries for Physics Simulations) is a library for electronic structure calculations using the density matrix renormalization group (DMRG) method.

Multiple choice

The splitting of d-orbitals in a coordination complex is primarily caused by:

  1. The electrostatic repulsion between electrons in the d-orbitals

  2. The interaction between the metal ion and the ligands

  3. The Jahn-Teller effect

  4. The Hund's rule
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In Ligand Field Theory, the splitting of d-orbitals is primarily caused by the interaction between the metal ion and the ligands. This interaction is influenced by the nature of the ligands, their symmetry, and the number of electrons in the d-orbitals.

Multiple choice

Which of the following statements is true about tetrahedral complexes?

  1. They exhibit a larger crystal field splitting energy compared to octahedral complexes

  2. They have a higher degree of orbital overlap between the metal ion and the ligands

  3. They are more stable than octahedral complexes

  4. None of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Tetrahedral complexes generally exhibit a smaller crystal field splitting energy, a lower degree of orbital overlap, and are less stable compared to octahedral complexes.