Coordination Compounds

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Summary

Summary of Coordination Compounds

Key Concepts

Isomers: Various isomers can be drawn for coordination complexes such as [CoCl₂(en)₂]⁺, [Co(NH₃)Cl(en)₂]⁺⁺, and [Co(NH₃)₂Cl₂(en)]⁺.
Geometrical Isomers: For example, [Pt(NH₃)(Br)(Cl)(py)] has geometrical isomers, some of which exhibit optical isomerism.
Color Changes: Aqueous copper sulfate shows different colors when reacted with potassium fluoride and potassium chloride due to complex formation.
Coordination Entities: Adding excess KCN to copper sulfate forms a new coordination entity without precipitating copper sulfide when H₂S is introduced.
Bonding Theories: The nature of bonding in coordination compounds can be explained using Valence Bond Theory and Crystal Field Theory.
Spectrochemical Series: Differentiates between weak and strong field ligands based on their ability to split d orbitals.
Magnetic Properties: Compounds like [Cr(NH₃)₆]³ are paramagnetic, while [Ni(CN)₄]² is diamagnetic due to their electron configurations.
Chelate Effect: Refers to the enhanced stability of chelating ligands compared to monodentate ligands.
Applications: Coordination compounds play vital roles in biological systems (e.g., hemoglobin), analytical chemistry, and industrial processes.

Important Definitions

Coordination Number: Number of sigma bonds formed by ligands with the central atom.
Coordination Sphere: The central atom and its attached ligands enclosed in square brackets.
Oxidation Number: Charge of the central atom if all ligands are removed with shared electrons.
Homoleptic vs. Heteroleptic: Homoleptic complexes have one type of ligand, while heteroleptic complexes have multiple types.

Examples of Coordination Compounds

Biological Importance: Chlorophyll (Mg), Hemoglobin (Fe), Vitamin B₁₂ (Co).
Industrial Use: Rhodium complexes in hydrogenation, electroplating with [Ag(CN)₂] and [Au(CN)₂].
Medicinal Applications: Chelate therapy using D-penicillamine and EDTA for metal toxicity.

Learning Objectives

Appreciate the postulates of Werner's theory of coordination compounds.
Understand the meaning of the terms: coordination entity, central atom/ion, ligand, coordination number, coordination sphere, coordination polyhedron, oxidation number, homoleptic, and heteroleptic.
Learn the rules of nomenclature of coordination compounds.
Write the formulas and names of mononuclear coordination compounds.
Define different types of isomerism in coordination compounds.
Understand the nature of bonding in coordination compounds in terms of Valence Bond and Crystal Field theories.
Appreciate the importance and applications of coordination compounds in daily life.

Detailed Notes

Coordination Compounds Notes

1. Isomers of Coordination Compounds

Geometrical and Optical Isomers
- (i) [CoCl₂(en)₂]⁺
- (ii) [Co(NH₃)Cl(en)₂]⁺⁺
- (iii) [Co(NH₃)₂Cl₂(en)]⁺
Geometrical Isomers of [Pt(NH₃)(Br)(Cl)(py)]
- Number of optical isomers: Not specified.

2. Experimental Results with Copper Sulphate

Aqueous Copper Sulphate
- (i) Green precipitate with potassium fluoride.
- (ii) Bright green solution with potassium chloride.

3. Coordination Entities and Reactions

Formation with KCN
- Coordination entity formed with excess KCN in copper sulphate solution: Not specified.
- No precipitate of copper sulphide with H₂S(g): Not specified.

4. Bonding in Coordination Entities (Valence Bond Theory)

Examples
- (i) [Fe(CN)₆]⁴
- (ii) [FeF₆]³⁻
- (iii) [Co(C₂O₄)₃]³⁻
- (iv) [CoF₆]³⁻

5. Crystal Field Theory

Splitting of d Orbitals
- Diagram to show the splitting in an octahedral crystal field: Not specified.
Spectrochemical Series
- Difference between weak field ligand and strong field ligand: Not specified.
Crystal Field Splitting Energy
- Magnitude's effect on d orbital configuration: Not specified.

6. Magnetic Properties of Complexes

Paramagnetic vs. Diamagnetic
- [Cr(NH₃)₆]³ is paramagnetic; [Ni(CN)₄]² is diamagnetic: Explanation not specified.
Color Differences
- [Ni(H₂O)₆]²⁺ is green; [Ni(CN)₄]² is colorless: Explanation not specified.

7. Color of Complexes

Violet Color of [Ti(H₂O)₆]³⁺
- Explanation based on crystal field theory: Not specified.

8. Chelate Effect

Definition and Example: Not specified.

9. Role of Coordination Compounds

Applications
- (i) Biological systems: Chlorophyll, haemoglobin, vitamin B₁₂.
- (ii) Medicinal chemistry: Chelate therapy for toxic metals.
- (iii) Analytical chemistry: Use of coordination compounds in detection and estimation.
- (iv) Extraction/metallurgy: Example of gold extraction with cyanide.

10. IUPAC Naming and Formulas

Oxidation State, d Orbital Occupation, Coordination Number
- Examples:
  - (i) K₃[Co(C₂O₄)₃]
  - (ii) cis-[CrCl₂(en)₂]Cl
  - (iii) (NH₄)₂[CoF₄]
  - (iv) [Mn(H₂O)₆]SO₄
Nomenclature Rules
- Cation named first, ligands in alphabetical order, oxidation state indicated in Roman numerals.

11. Types of Isomerism

Examples of Isomerism: Not specified.

12. Coordination Number and Polyhedron

Definition: Coordination number determined by the number of sigma bonds formed by ligands.
Coordination Polyhedron: Spatial arrangement of ligand atoms around the central atom. Common types include octahedral, square planar, and tetrahedral.

13. Importance of Coordination Compounds

Applications: Used in various fields including biological systems, analytical chemistry, and industrial processes.

Exam Tips & Common Mistakes

Common Mistakes and Exam Tips

Common Pitfalls

Misidentifying Isomers: Students often confuse geometrical and optical isomers. Ensure to differentiate between the two types clearly.
Incorrect Coordination Numbers: Be cautious when determining the coordination number of a complex; remember it is based solely on sigma bonds formed by ligands.
Neglecting Ligand Types: Failing to recognize whether ligands are unidentate, bidentate, or ambidentate can lead to errors in naming and drawing structures.
Overlooking Oxidation States: Always calculate the oxidation state of the central metal ion correctly; this is crucial for naming and understanding the properties of the complex.
Ignoring Crystal Field Theory: Many students forget to apply crystal field theory when explaining color differences in complexes, which can lead to incomplete answers.

Tips for Success

Practice Drawing Structures: Regularly practice drawing the structures of coordination compounds, including their isomers, to reinforce your understanding.
Memorize Key Definitions: Make sure to memorize definitions such as coordination sphere, coordination polyhedron, and types of ligands.
Use Visual Aids: Diagrams can help visualize the spatial arrangements of ligands and the geometry of complexes, aiding in understanding.
Review Spectrochemical Series: Familiarize yourself with the spectrochemical series, as it helps in predicting the behavior of ligands in complexes.
Understand the Importance of Chelation: Recognize the significance of the chelate effect in coordination chemistry, as it often appears in exam questions.

Practice & Assessment

Multiple Choice Questions

[Ni(CO)₄]

[Ag(CN)₂]

[Au(CN)₂]

[Co(NH₃)₆]³⁺

Correct Answer: A

Solution:

Impure nickel is converted to [Ni(CO)₄], which is decomposed to yield pure nickel.

Correct Answer: C

Solution:

The coordination number is determined by the number of sigma bonds formed by the ligands with the central metal ion. In [Co(NH₃)₄Cl₂]⁺, there are six sigma bonds, hence the coordination number is 6.

[(Ph₃P)₃RhCl]

[Co(NH₃)₆]³⁺

[Ni(CO)₄]

[Pt(NH₃)₂Cl₂]

Correct Answer: A

Solution:

The rhodium complex [(Ph₃P)₃RhCl], known as Wilkinson's catalyst, is used for the hydrogenation of alkenes.

Geometrical isomerism only

Optical isomerism only

Both geometrical and optical isomerism

Neither geometrical nor optical isomerism

Correct Answer: C

Solution:

The complex [Pt(NH₃)(Br)(Cl)(py)] can exhibit both geometrical and optical isomerism due to the different possible arrangements of ligands around the central metal.

Correct Answer: B

Solution:

In K[Cr(H₂O)₂(C₂O₄)₂]·3H₂O, the oxidation state of chromium can be calculated by considering the charges: K⁺ is +1, each oxalate (C₂O₄)²⁻ is -2, and water is neutral. Therefore, Cr must be +3 to balance the charge.

Chlorophyll

Haemoglobin

Vitamin B₁₂

Carboxypeptidase A

Correct Answer: C

Solution:

Vitamin B₁₂, also known as cyanocobalamine, is a coordination compound of cobalt and is important in biological systems.

Correct Answer: C

Solution:

In solution, Co(NH₃)₆Cl₂ dissociates into one Co(NH₃)₆³⁺ ion and two Cl⁻ ions, resulting in a total of 3 ions.

EDTA

D-penicillamine

Desferrioxime B

Cis-platin

Correct Answer: B

Solution:

D-penicillamine is used to remove excess copper via the formation of coordination compounds.

[Ag(CN)₂]⁻

EDTA

[Au(CN)₂]⁻

cis-platin

Correct Answer: B

Solution:

EDTA is used in chelation therapy to treat lead poisoning due to its ability to bind to metal ions and facilitate their excretion from the body.

Double salts dissociate completely in water, while complexes do not.

Complexes dissociate completely in water, while double salts do not.

Both double salts and complexes dissociate completely in water.

Neither double salts nor complexes dissociate completely in water.

Correct Answer: A

Solution:

Double salts dissociate into simple ions completely when dissolved in water, whereas complexes do not dissociate into their constituent ions.

Chlorophyll

Haemoglobin

Vitamin B₁₂

Carbonic anhydrase

Correct Answer: C

Solution:

Vitamin B₁₂, cyanocobalamine, is a coordination compound of cobalt and acts as an anti-pernicious anaemia factor.

[Ni(CO)₄]

[(Ph₃P)₃RhCl]

[Ag(CN)₂]⁻

[Au(CN)₂]⁻

Correct Answer: B

Solution:

[(Ph₃P)₃RhCl] is known as Wilkinson's catalyst and is used for the hydrogenation of alkenes.

Valence Bond Theory

Crystal Field Theory

Molecular Orbital Theory

Werner's Theory

Correct Answer: A

Solution:

The Valence Bond Theory explains the formation, magnetic behaviour, and geometrical shapes of coordination compounds.

Chelating agent for lead poisoning

Chelating agent for copper toxicity

Catalyst for hydrogenation

Stabilizer for photographic film

Correct Answer: B

Solution:

D-penicillamine acts as a chelating agent to remove excess copper from the body, particularly in conditions like Wilson's disease.

Acts as a reducing agent

Acts as a chelating agent

Acts as an oxidizing agent

Acts as a precipitating agent

Correct Answer: B

Solution:

EDTA is a chelating agent that forms stable complexes with metal ions, and it is used in various applications, including the treatment of metal poisoning.

Chlorophyll

Vitamin B₁₂

Haemoglobin

Carbonic anhydrase

Correct Answer: C

Solution:

Haemoglobin is a coordination compound of iron and is responsible for the red pigment in blood, acting as an oxygen carrier.

Correct Answer: B

Solution:

The coordination number is determined by the number of sigma bonds formed by the ligand with the central atom. In [Ni(CO)₄], there are four CO ligands, so the coordination number is 4.

Correct Answer: A

Solution:

In K₄[Fe(CN)₆], the complex ion [Fe(CN)₆]⁴⁻ has a charge of -4. Since each CN⁻ ligand has a charge of -1, the oxidation state of iron must be +2 to balance the charges.

Chlorophyll

[Cr(CN)₆]³⁻

[Cr(H₂O)₆]³⁺

Haemoglobin

Correct Answer: C

Solution:

In emerald, Cr³⁺ ions occupy octahedral sites in the mineral beryl, causing it to transmit light in the green region.

Difference in oxidation states of nickel

Difference in crystal field splitting energy

Difference in coordination numbers

Difference in ligand field strength

Correct Answer: D

Solution:

[Ni(CN)₄]²⁻ is diamagnetic due to the strong field nature of CN⁻ ligands, which cause pairing of electrons. In contrast, [NiCl₄]²⁻ is paramagnetic due to the weak field nature of Cl⁻ ligands, which do not cause electron pairing.

[Ag(CN)₂]⁻

[Ag(NH₃)₂]⁺

[AgCl₂]⁻

[Ag(S₂O₃)₂]³⁻

Correct Answer: A

Solution:

The complex [Ag(CN)₂]⁻ is used for smooth and even electroplating of silver as it provides a stable complex ion that facilitates the deposition of silver metal from solution.

Causes small splitting of d orbitals

Forms high spin complexes

Causes large splitting of d orbitals

Forms paramagnetic complexes

Correct Answer: C

Solution:

Strong field ligands cause a large splitting of the d orbitals, which can lead to the formation of low spin complexes.

It distinguishes between primary and secondary valences.

It explains the optical properties of coordination compounds.

It provides a quantitative interpretation of magnetic behavior.

It accounts for the covalent character of metal-ligand bonding.

Correct Answer: A

Solution:

Werner's theory postulates the existence of primary and secondary valences in coordination compounds, which are now understood as ionic and covalent bonds, respectively.

Correct Answer: B

Solution:

In the complex K₃[Co(C₂O₄)₃], the oxidation state of cobalt is +3.

EDTA

cis-platin

Vitamin B₁₂

Chlorophyll

Correct Answer: A

Solution:

EDTA is used in chelate therapy to treat lead poisoning by forming stable coordination compounds with metal ions.

They are used as structural components in bones.

They act as catalysts in photosynthesis and oxygen transport.

They are solely responsible for DNA replication.

They provide energy through ATP synthesis.

Correct Answer: B

Solution:

Coordination compounds like chlorophyll and haemoglobin act as catalysts in photosynthesis and oxygen transport, respectively.

It is purely ionic.

It is purely covalent.

It involves both σ and π character.

It is purely metallic.

Correct Answer: C

Solution:

The metal-carbon bond in metal carbonyls involves both σ and π character, with a σ bond formed by the donation of lone pair electrons from the carbonyl carbon and a π bond formed by back-donation from the metal to the carbonyl.

It arranges ligands based on their ionic character.

It arranges ligands based on their ability to split d orbitals.

It arranges ligands based on their molecular weight.

It arranges ligands based on their boiling points.

Correct Answer: B

Solution:

The spectrochemical series arranges ligands based on their ability to split the d orbitals of the central metal ion in a coordination complex.

It is tetrahedral and paramagnetic.

It is square planar and diamagnetic.

It is octahedral and paramagnetic.

It is square planar and paramagnetic.

Correct Answer: B

Solution:

[Ni(CN)₄]²⁻ is square planar and diamagnetic due to the strong field ligand CN⁻ causing pairing of electrons.

CN⁻ is a weak field ligand causing pairing of electrons.

Cl⁻ is a strong field ligand causing pairing of electrons.

CN⁻ is a strong field ligand causing pairing of electrons.

Cl⁻ is a weak field ligand causing pairing of electrons.

Correct Answer: C

Solution:

CN⁻ is a strong field ligand that causes pairing of electrons in [Ni(CN)₄]²⁻, making it diamagnetic, while Cl⁻ is a weak field ligand, resulting in unpaired electrons in [NiCl₄]²⁻, making it paramagnetic.

EDTA acts as a reducing agent.

EDTA forms a coordination complex with lead, facilitating its removal.

EDTA oxidizes lead to a non-toxic form.

EDTA precipitates lead as an insoluble salt.

Correct Answer: B

Solution:

EDTA acts as a chelating agent that forms a stable coordination complex with lead ions, which helps in their removal from the body.

[PtCl₄]²⁻

[Ni(CO)₄]

[Co(NH₃)₆]³⁺

[Fe(CN)₆]³⁻

Correct Answer: A

Solution:

[PtCl₄]²⁻ is a square planar complex, while [Ni(CO)₄] is tetrahedral, [Co(NH₃)₆]³⁺ is octahedral, and [Fe(CN)₆]³⁻ is also octahedral.

It explains the optical properties of coordination compounds.

It postulates the use of two types of linkages by a metal atom/ion.

It provides a quantitative interpretation of magnetic behaviour.

It considers ligands as point charges.

Correct Answer: B

Solution:

Werner's theory postulates the use of primary and secondary valences, which are now recognized as ionic and covalent bonds.

[Ag(CN)₂]⁻

[Au(CN)₂]⁻

[Co(NH₃)₆]³⁺

[Ni(CN)₄]²⁻

Correct Answer: A

Solution:

Articles can be electroplated with silver from solutions of the complex [Ag(CN)₂]⁻.

[Fe(CN)_6]^{3-}

[Ni(CO)_4]

[CoF_6]^{3-}

[Fe(H_2O)_6]^{3+}

Correct Answer: B

Solution:

[Ni(CO)_4] is diamagnetic because it has no unpaired electrons in its electronic configuration.

D-penicillamine

Desferrioxime B

EDTA

Cis-platin

Correct Answer: C

Solution:

EDTA is used in the treatment of lead poisoning by forming coordination compounds with lead.

NH₃

Cl⁻

en (ethylenediamine)

CN⁻

Correct Answer: C

Solution:

Ethylenediamine (en) is a bidentate ligand that can form two bonds with a metal ion, making it a chelating ligand.

Coordination number: 6, Oxidation state: +3

Coordination number: 4, Oxidation state: +3

Coordination number: 6, Oxidation state: +2

Coordination number: 4, Oxidation state: +2

Correct Answer: A

Solution:

In K₃[Co(C₂O₄)₃], the coordination number is 6 due to three bidentate oxalate ligands, and the oxidation state of Co is +3.

Vitamin B₁₂

Chlorophyll

Haemoglobin

EDTA

Correct Answer: A

Solution:

Vitamin B₁₂, also known as cyanocobalamine, is a coordination compound of cobalt.

Iodide (I⁻)

Cyanide (CN⁻)

Water (H₂O)

Ammonia (NH₃)

Correct Answer: B

Solution:

Cyanide (CN⁻) is a strong field ligand compared to iodide, water, and ammonia.

[Ag(CN)₂]

[Au(CN)₂]

[Ni(CO)₄]

[Fe(CN)₆]⁴⁻

Correct Answer: B

Solution:

The complex [Au(CN)₂] is used in the electroplating of gold.

[Ag(CN)₂]⁻

[Au(CN)₂]⁻

[Ag(S₂O₃)₂]³⁻

[Fe(CN)₆]⁴⁻

Correct Answer: C

Solution:

In black and white photography, the developed film is fixed by washing with hypo solution which dissolves the undecomposed AgBr to form the complex ion [Ag(S₂O₃)₂]³⁻.

Correct Answer: B

Solution:

The complex [Co(NH₃)₄Cl₂]⁺ is an octahedral complex and can have two geometrical isomers: cis and trans.

Chlorophyll

Haemoglobin

Vitamin B₁₂

Carboxypeptidase A

Correct Answer: B

Solution:

Haemoglobin, a coordination compound of iron, is responsible for the red color of blood.

[Co(NH₃)₆]³⁺

[Co(NH₃)₄Cl₂]⁺

[Ni(CO)₄]

[PtCl₄]

Correct Answer: B

Solution:

A heteroleptic complex is one in which a metal is bound to more than one kind of donor group. [Co(NH₃)₄Cl₂]⁺ has ammonia and chloride as ligands, making it heteroleptic.

Correct Answer: A

Solution:

The primary valence of cobalt in [Co(NH₃)₆]Cl₃ is 3, corresponding to the oxidation state of the cobalt ion in the complex.

EDTA

Cis-platin

Vitamin B₁₂

Haemoglobin

Correct Answer: A

Solution:

EDTA is used in the treatment of lead poisoning due to its ability to form stable complexes with lead ions.

Correct Answer: C

Solution:

Co(NH₃)₆Cl₂ dissociates into Co(NH₃)₆²⁺ and 2 Cl⁻ ions, producing a total of 3 ions.

[Cu(CN)₄]²⁻

[Cu(CN)₂]⁻

[Cu(CN)₃]⁻

[Cu(CN)₆]⁴⁻

Correct Answer: A

Solution:

When excess KCN is added to copper sulphate, the complex [Cu(CN)₄]²⁻ is formed.

[Ag(CN)₂]⁻

[Au(CN)₂]⁻

[Co(NH₃)₆]³⁺

[Ni(CO)₄]

Correct Answer: B

Solution:

Gold is electroplated from solutions of the complex [Au(CN)₂]⁻.

Correct Answer: C

Solution:

The coordination number is determined by the number of sigma bonds formed by ligands with the central metal. In [Co(NH₃)₆]³⁺, there are six ammonia ligands, thus the coordination number is 6.

H₂O

NH₃

CN⁻

Cl⁻

Correct Answer: C

Solution:

CN⁻ is considered a strong field ligand, which causes a large splitting of the d orbitals in crystal field theory.

Valence Bond Theory

Crystal Field Theory

Molecular Orbital Theory

Ligand Field Theory

Correct Answer: A

Solution:

The Valence Bond Theory explains the formation, magnetic behavior, and geometrical shapes of coordination compounds but fails to provide a quantitative interpretation of magnetic behavior.

Chlorophyll

Haemoglobin

Vitamin B₁₂

Cis-platin

Correct Answer: C

Solution:

Vitamin B₁₂, also known as cyanocobalamine, is a coordination compound of cobalt and is used as an anti-pernicious anemia factor.

It is used in the treatment of copper poisoning.

It forms a coordination compound with platinum.

It is used in the treatment of lead poisoning.

It is a strong field ligand that causes high spin complexes.

Correct Answer: C

Solution:

EDTA is used in the treatment of lead poisoning due to its ability to form stable complexes with lead ions, facilitating their removal from the body.

The solution turns bright green.

The solution turns blue.

The solution turns red.

The solution turns yellow.

Correct Answer: A

Solution:

When aqueous copper sulfate reacts with potassium chloride, a bright green solution is formed due to the formation of a complex ion.

Correct Answer: C

Solution:

The coordination number is determined by the number of sigma bonds formed by the ligands. In [Co(NH₃)₆]³⁺, there are six ammonia ligands, so the coordination number is 6.

Oxygen transport in blood

Photosynthesis

DNA replication

Vitamin B₁₂ function

Correct Answer: C

Solution:

Coordination compounds play roles in oxygen transport (haemoglobin), photosynthesis (chlorophyll), and vitamin B₁₂ function, but they are not directly involved in DNA replication.

[Co(NH₃)₆]³⁺

[Cr(C₂O₄)₃]³⁻

[Cr(NH₃)₆]³⁺

[Ni(CN)₄]²⁻

Correct Answer: B

Solution:

In emeralds, Cr³⁺ ions occupy octahedral sites in the mineral beryl, causing the green color.

[Co(NH₃)₆]³⁺

[Co(NH₃)₄Cl₂]⁺

[Pt(NH₃)(Br)(Cl)(py)]

[Fe(CN)₆]⁴⁻

Correct Answer: A

Solution:

A homoleptic complex is one in which a metal is bound to only one kind of donor group. [Co(NH₃)₆]³⁺ is homoleptic as it has only NH₃ as ligands.

[Ag(CN)₂]⁻

[Au(CN)₂]⁻

[Ni(CO)₄]

[Co(NH₃)₆]³⁺

Correct Answer: A

Solution:

Silver is electroplated using the complex [Ag(CN)₂]⁻, as it allows for a smooth and even deposition of silver.

They form complexes with gold, allowing it to be separated from ores.

They act as catalysts in the extraction process.

They reduce gold ions to metallic gold.

They oxidize gold to a higher oxidation state.

Correct Answer: A

Solution:

In the extraction of gold, coordination compounds like [Au(CN)₂]⁻ are formed, which allows gold to be separated from ores.

[Ni(CO)₄]

[(Ph₃P)₃RhCl]

[Ag(CN)₂]

[Au(CN)₂]

Correct Answer: B

Solution:

The rhodium complex [(Ph₃P)₃RhCl], known as Wilkinson's catalyst, is used for the hydrogenation of alkenes.

True or False

Correct Answer: False

Solution:

The assumption that anionic ligands exert the greatest splitting effect is incorrect, as they are found at the low end of the spectrochemical series.

Correct Answer: True

Solution:

In black and white photography, the developed film is fixed by washing with hypo solution which dissolves the undecomposed AgBr to form a complex ion, [Ag(S₂O₃)₂]³⁻.

Correct Answer: True

Solution:

Chlorophyll, the pigment responsible for photosynthesis, is indeed a coordination compound of magnesium.

Correct Answer: True

Solution:

Chlorophyll is indeed a coordination compound of magnesium, as mentioned in the provided excerpts.

Correct Answer: True

Solution:

The complex [Pt(NH₃)(Br)(Cl)(py)] can show geometrical isomerism due to different possible arrangements of ligands around the central platinum ion, and some of these geometrical isomers can also exhibit optical isomerism.

Correct Answer: False

Solution:

Haemoglobin is a coordination compound of iron, not magnesium.

Correct Answer: True

Solution:

Werner's theory indeed postulates the use of primary and secondary valences in coordination compounds.

Correct Answer: True

Solution:

[Cr(NH₃)₆]³⁺ is paramagnetic due to the presence of unpaired electrons.

Correct Answer: True

Solution:

A homoleptic complex is one in which a metal is bound to only one kind of donor group. In [Co(NH₃)₆]Cl₃, cobalt is bound to six ammonia molecules, making it homoleptic.

Correct Answer: False

Solution:

The coordination number is determined by the number of sigma bonds formed by the ligand with the central atom, not pi bonds.

Correct Answer: False

Solution:

Vitamin B₁₂, or cyanocobalamine, is a coordination compound of cobalt, not iron.

Correct Answer: True

Solution:

The hypo solution dissolves the undecomposed AgBr to form the complex ion [Ag(S₂O₃)₂]³⁻, which is crucial in the photographic fixing process.

Correct Answer: False

Solution:

The Valence Bond Theory (VBT) explains the formation, magnetic behavior, and geometrical shapes of coordination compounds, but it fails to provide a quantitative interpretation of magnetic behavior.

Correct Answer: False

Solution:

Coordination compounds find extensive applications in medicinal chemistry, such as in chelate therapy and cancer treatment.

Correct Answer: True

Solution:

Cis-platin is a well-known coordination compound used in chemotherapy to inhibit tumor growth.

Correct Answer: False

Solution:

[Co(NH₃)₆]³⁺ is actually octahedral, not square planar.

Correct Answer: True

Solution:

[Ni(CN)₄]²⁻ is diamagnetic because its square planar structure leads to the pairing of all electrons.

Correct Answer: True

Solution:

Impure nickel is converted to

[\text{Ni(CO)}_4]

, which is decomposed to yield pure nickel.

Correct Answer: False

Solution:

The metal-carbon bond in metal carbonyls possesses both

\sigma

and

\pi

character, indicating a covalent nature rather than purely ionic.

Correct Answer: True

Solution:

Werner's theory postulated the use of two types of linkages (primary and secondary) by a metal atom/ion in a coordination compound.

Correct Answer: False

Solution:

The coordination number is determined only by the number of sigma bonds formed by the ligand with the central atom/ion. Pi bonds are not counted for this purpose.

Correct Answer: True

Solution:

The coordination number is indeed determined by the number of sigma bonds formed by the ligands with the central atom.

Correct Answer: True

Solution:

EDTA is a chelating agent that forms coordination compounds with lead, effectively removing it from the body, thus it is used in the treatment of lead poisoning.

Correct Answer: False

Solution:

[Fe(CN)₆]⁴⁻ is diamagnetic because the strong field cyanide ligands cause pairing of electrons in the d orbitals of iron.

Correct Answer: True

Solution:

In metal carbonyls, the metal-carbon bond is characterized by

\sigma

bonding from the carbonyl carbon to the metal and

\pi

back-bonding from the metal to the carbonyl.

Correct Answer: False

Solution:

In [Fe(CN)₆]⁴⁻, the metal-carbon bond is not purely ionic; it involves covalent character as well.

Correct Answer: True

Solution:

Chlorophyll is indeed a coordination compound of magnesium, which plays a crucial role in the process of photosynthesis.

Correct Answer: True

Solution:

The coordination compound [Ni(CO)₄] is indeed tetrahedral, as indicated by its structural description.

Correct Answer: True

Solution:

Articles can be electroplated with silver more smoothly and evenly from solutions of the complex

[\text{Ag(CN)}_2]

Correct Answer: True

Solution:

The Crystal Field Theory (CFT) to coordination compounds is based on the effect of different crystal fields provided by the ligands taken as point charges.

Correct Answer: False

Solution:

Haemoglobin is a coordination compound of iron, not cobalt.

Correct Answer: False

Solution:

The metal-carbon bond in metal carbonyls has both sigma and pi character. The ligand to metal is a sigma bond and metal to ligand is a pi bond.

Correct Answer: True

Solution:

The Crystal Field Theory explains the splitting of d orbitals in coordination compounds, which affects their electronic arrangements and properties.

Correct Answer: False

Solution:

Chlorophyll is a coordination compound of magnesium, not iron. Haemoglobin is the coordination compound of iron.

Correct Answer: True

Solution:

Impure nickel is converted to [Ni(CO)₄], which is then decomposed to yield pure nickel.

Correct Answer: True

Solution:

In black and white photography, the developed film is fixed by washing with hypo solution, which dissolves the undecomposed AgBr to form the complex ion [Ag(S₂O₃)₂]³.

Correct Answer: True

Solution:

Cis-platin is a coordination compound of platinum that is effectively used to inhibit the growth of tumors.

Correct Answer: True

Solution:

The hypo solution dissolves undecomposed AgBr to form a complex ion, [Ag(S₂O₃)₂]³⁻, fixing the film.

Correct Answer: True

Solution:

The coordination number is indeed determined by the number of sigma bonds formed between the ligands and the central atom/ion.

Correct Answer: True

Solution:

Coordination compounds, such as

[\text{Ag(CN)}_2]^-

and

[\text{Au(CN)}_2]^-

, are used in electroplating to achieve smooth and even coatings.

Correct Answer: False

Solution:

The metal-carbon bond in metal carbonyls possesses both sigma and pi character.

Correct Answer: True

Solution:

In metal carbonyls, the metal-carbon bond is formed by sigma donation from the carbonyl carbon and pi back-donation from the metal.

Correct Answer: True

Solution:

The undecomposed AgBr is dissolved by washing with a hypo solution, forming the complex ion [Ag(S₂O₃)₂]³⁻.

Correct Answer: True

Solution:

EDTA is used in chelate therapy to treat lead poisoning by forming coordination compounds with lead ions.

Correct Answer: False

Solution:

EDTA is used in the treatment of lead poisoning, not copper poisoning. D-penicillamine is used for copper.

Correct Answer: True

Solution:

The complex [Ni(CO)₄] is tetrahedral because it involves coordination with four carbon monoxide ligands and is diamagnetic due to the absence of unpaired electrons.

Correct Answer: True

Solution:

The hypo solution dissolves the undecomposed AgBr by forming the complex ion [Ag(S₂O₃)₂]³⁻, thus fixing the film.

Correct Answer: True

Solution:

Werner's theory introduced the concept of primary and secondary valences and used isomerism to predict the geometrical shapes of coordination compounds.

Correct Answer: True

Solution:

Werner's theory indeed was the first systematic attempt to explain the formation, reactions, structure, and bonding of coordination compounds.

Correct Answer: True

Solution:

CFT is based on the effect of different crystal fields provided by ligands considered as point charges.

Correct Answer: True

Solution:

A homoleptic complex is one in which the central metal ion is bound to only one type of ligand. In [Co(NH₃)₆]³⁺, the cobalt ion is coordinated with six ammonia ligands.

Correct Answer: True

Solution:

Werner's theory was the first systematic attempt to explain the formation, reactions, structure, and bonding of coordination compounds, including their optical properties.

Correct Answer: False

Solution:

EDTA is used in the treatment of lead poisoning, while D-penicillamine and desferrioxime B are used to remove excess copper and iron.

Correct Answer: False

Solution:

The Valence Bond Theory does not provide a quantitative interpretation of the optical properties of coordination compounds.

Correct Answer: True

Solution:

In an octahedral crystal field, the d orbitals split into two sets of energy levels: the lower energy t₂g and the higher energy e_g levels.

Correct Answer: False

Solution:

The Valence Bond Theory does not provide a quantitative interpretation of magnetic behavior; it only explains the formation, magnetic behavior, and geometrical shapes qualitatively.

Correct Answer: False

Solution:

Aqueous copper sulphate solution gives a green precipitate with aqueous potassium fluoride, not a bright green solution.

Correct Answer: True

Solution:

Chlorophyll is indeed a coordination compound of magnesium, which plays a crucial role in photosynthesis.

Correct Answer: True

Solution:

A homoleptic complex is one in which the metal is bound to only one kind of donor group. In [Co(NH₃)₆]³⁺, cobalt is bound to ammonia ligands only.

Correct Answer: False

Solution:

Haemoglobin is a coordination compound of iron, not magnesium.

Coordination Compounds

AI Learning Assistant

Summary

Summary of Coordination Compounds

Key Concepts

Important Definitions

Examples of Coordination Compounds

Learning Objectives

Learning Objectives

Detailed Notes

Coordination Compounds Notes

1. Isomers of Coordination Compounds

2. Experimental Results with Copper Sulphate

3. Coordination Entities and Reactions

4. Bonding in Coordination Entities (Valence Bond Theory)

5. Crystal Field Theory

6. Magnetic Properties of Complexes

7. Color of Complexes

8. Chelate Effect

9. Role of Coordination Compounds

10. IUPAC Naming and Formulas

11. Types of Isomerism

12. Coordination Number and Polyhedron

13. Importance of Coordination Compounds

Exam Tips & Common Mistakes

Common Mistakes and Exam Tips

Common Pitfalls

Tips for Success

Practice & Assessment

Multiple Choice Questions

Q1.Which of the following coordination compounds is used in the purification of nickel?

Correct Answer: A

Q2.What is the coordination number of the central metal ion in the complex [Co(NH₃)₄Cl₂]⁺?

Correct Answer: C

Q3.Which of the following complexes is used as a catalyst in the hydrogenation of alkenes?

Correct Answer: A

Q4.What type of isomerism is exhibited by the complex [Pt(NH₃)(Br)(Cl)(py)]?

Correct Answer: C

Q5.What is the oxidation state of chromium in the complex K[Cr(H₂O)₂(C₂O₄)₂]·3H₂O?

Correct Answer: B

Q6.Which of the following is a coordination compound of cobalt that is important in biological systems?

Correct Answer: C

Q7.How many ions are produced from the complex Co(NH₃)₆Cl₂ in solution?

Correct Answer: C

Q8.Which coordination compound is used in the treatment of excess copper in biological systems?

Correct Answer: B

Q9.Which of the following coordination compounds is used in the treatment of lead poisoning?

Correct Answer: B

Q10.In the context of coordination compounds, which of the following statements correctly describes the difference between a double salt and a complex?

Correct Answer: A

Q11.Which of the following is a coordination compound of cobalt that acts as an anti-pernicious anaemia factor?

Correct Answer: C

Q12.Which of the following coordination compounds is used in the hydrogenation of alkenes?

Correct Answer: B

Q13.Which theory explains the formation, magnetic behaviour, and geometrical shapes of coordination compounds?

Correct Answer: A

Q14.In the context of coordination chemistry, what is the role of D-penicillamine?

Correct Answer: B

Q15.What is the role of EDTA in coordination chemistry?

Correct Answer: B

Q16.Which coordination compound is responsible for the red pigment in blood that acts as an oxygen carrier?

Correct Answer: C

Q17.What is the coordination number of the central metal ion in the complex [Ni(CO)₄]?

Correct Answer: B

Q18.In the complex K₄[Fe(CN)₆], what is the oxidation state of iron?

Correct Answer: A

Q19.Which of the following coordination compounds is responsible for the green color of an emerald?

Correct Answer: C

Q20.What is the primary reason that [Ni(CN)₄]²⁻ is diamagnetic while [NiCl₄]²⁻ is paramagnetic?

Correct Answer: D

Q21.Which of the following coordination compounds can be used to smooth and even electroplating of silver?

Correct Answer: A

Q22.Which of the following is a characteristic of a strong field ligand?

Correct Answer: C

Q23.Which of the following is a characteristic feature of Werner's theory of coordination compounds?

Correct Answer: A

Q24.What is the oxidation state of cobalt in the complex K₃[Co(C₂O₄)₃]?

Correct Answer: B

Q25.Which of the following is an example of a coordination compound used in chelate therapy?

Correct Answer: A