Case: A coordination compound is formed by the coordination of a metal ion with ligands through coordinate covalent bonds. The central metal ion in a coordination compound is typically a transition metal, which can accept electron pairs from ligands. The number of ligands attached to the metal ion determines the coordination number of the complex. For example, in the complex [Cu(NH₃)₄]²⁺, copper is surrounded by four ammonia molecules (NH₃) forming a coordination number of 4.
The formation of coordination compounds is an essential aspect of coordination chemistry, and they have applications in various fields such as catalysis, medicine, and industrial processes. One of the key concepts in the formation of coordination compounds is understanding the nature of metal-ligand bonding and the coordination sphere, where the metal ion is at the center and is surrounded by the ligands.
Questions:
In the complex [Cu(NH₃)₄]²⁺, what is the coordination number of copper (Cu)?
A coordinate covalent bond is formed when:
Which of the following is a monodentate ligand?
In the complex [Cu(NH₃)₄]²⁺, what is the charge on the complex?
Case: Ligands are ions or molecules that bind to the central metal ion in a coordination compound. Ligands can be classified based on the number of donor atoms they have, and this classification is important for understanding the structure and reactivity of coordination complexes. Monodentate ligands, like chloride (Cl⁻) and ammonia (NH₃), have one donor atom, while bidentate ligands, such as ethylenediamine (en), have two donor atoms. Polydentate ligands, like ethylenediaminetetraacetic acid (EDTA), can bind through multiple donor atoms.
The type of ligand affects the geometry and stability of the coordination complex. For example, when ethylenediamine is used as a ligand, it forms a chelate with the metal ion, making the complex more stable due to the chelate effect.
Questions:
Which of the following is a bidentate ligand?
Which of the following is a polydentate ligand?
Monodentate ligands have:
The chelate effect refers to:
Case: Crystal Field Theory (CFT) is used to explain the electronic structure, magnetic properties, and color of coordination compounds. According to CFT, when ligands approach a central metal ion, they cause a splitting of the metal ion's d-orbitals into two energy levels. The extent of this splitting depends on the geometry of the complex and the nature of the ligands. For example, in an octahedral complex, the five d-orbitals split into two sets, with three orbitals (e₁g) at lower energy and two orbitals (t₂g) at higher energy.
The crystal field splitting energy (Δ₀) is a key factor in determining the stability and color of coordination compounds. A large value of Δ₀ results in a strong field complex, while a small Δ₀ leads to a weak field complex. The electronic configuration of the metal ion, the ligand field strength, and the geometry of the complex all contribute to the magnetic properties and color of the coordination compound.
Questions:
In an octahedral crystal field, the d-orbitals split into:
The color of a coordination compound is due to:
A weak field ligand would cause:
The magnetic properties of coordination compounds depend on:
Case: Valency Bond Theory (VBT) is another method used to describe the bonding in coordination compounds. According to VBT, a metal ion can form bonds with ligands by overlapping its empty orbitals with the filled orbitals of the ligands. In the case of an octahedral complex, the metal ion undergoes hybridization, typically sp³d² hybridization, to form six bonds with the ligands.
For example, in the complex [Co(NH₃)₆]³⁺, cobalt (Co) undergoes sp³d² hybridization to form six bonds with ammonia (NH₃) molecules. VBT also explains the geometry of coordination complexes, where the arrangement of ligands around the metal ion depends on the hybridization of the metal’s orbitals.
Questions:
According to Valency Bond Theory, the central metal ion in an octahedral complex undergoes:
In the complex [Co(NH₃)₆]³⁺, the geometry of the complex is:
The formation of coordinate bonds in a coordination complex involves:
In the coordination complex [Co(NH₃)₆]³⁺, the oxidation state of cobalt is:
Case: Coordination compounds can exhibit isomerism, where compounds with the same molecular formula have different structures or spatial arrangements. Two main types of isomerism are coordination isomerism and geometrical isomerism. Coordination isomerism occurs when the ligands in a coordination compound are exchanged between metal ions in a multi-metal complex. Geometrical isomerism is common in square planar and octahedral complexes, where ligands can be arranged differently around the metal ion.
For example, in the complex [CoCl₂(NH₃)₄]Cl, there are possible coordination isomers where the chloride ions can either coordinate to the metal ion or exist as counterions.
Questions:
Geometrical isomerism is most commonly observed in:
Coordination isomerism arises due to the exchange of ligands between:
In the complex [CoCl₂(NH₃)₄]Cl, the chloride ions can either be:
The number of possible geometrical isomers increases with: