Question

Among the properties (A) reducing (B) oxidizing (C) complexing, the set of properties shown by CN ion towards metal species is (a) A, B (b) \(\mathrm{B}, \mathrm{C}\) (c) \(\mathrm{C}, \mathrm{A}\) (d) A, B, C

Short answer

The CN ion exhibits properties (B, C), specifically oxidizing and complexing.

Step-by-step solution

Identify Chemical Nature of CN⁻ Ion

The cyanide ion (CN⁻) is a negatively charged ion known for its ability to form strong complexes with transition metals. This is a clue about its complexing ability (Property C).

Evaluate Reducing Nature (Property A)

The CN⁻ ion is not typically recognized as a reducing agent in standard chemistry contexts. Reducing agents donate electrons in redox reactions, but CN⁻ does not usually act this way.

Assess Oxidizing Nature (Property B)

The CN⁻ ion also does not act as an oxidizing agent. Oxidizing agents accept electrons, which is not a common characteristic of CN⁻.

Confirm Complexing Property

Since CN⁻ forms complexes with metal ions, it exhibits a strong tendency to act as a ligand, indicating it has complexing properties (Property C).

Conclusion from Evaluation

Based on the analysis, CN⁻ exhibits complexing properties (C) but not reducing (A) or oxidizing (B) properties. Therefore, the correct set of properties is (B, C).

Key concepts

Cyanide Ion

The cyanide ion, represented as CN⁻, is a small, negatively charged ion consisting of a carbon atom triple-bonded to a nitrogen atom. This unique structure gives it distinct chemical properties.
The ionic nature of CN⁻ makes it highly reactive, especially in the context of transition metals. The triple bond in CN⁻ consists of a sigma and two pi bonds, granting it substantial stability and strength, although paradoxically, it is also highly reactive under certain conditions.
Cyanide ions are known for their ability to form stable complexes with various metals. This is largely attributed to its lone pair of electrons on the carbon atom, which can form coordinate covalent bonds with metal centers, acting as a stabilizing ligand in complexation reactions.

• Acts as a strong ligand: CN⁻ readily forms more stable and persistent complexes than many other ligands, even in varied chemical environments.
• Has a high affinity for metal ions, especially transition metals, demonstrating strong complexation properties.

Understanding these characteristics of the cyanide ion provides valuable insight into its role in chemical bonding and reactivity.

Transition Metals

Transition metals are a group of metals found in the center of the periodic table, more specifically, they include elements from groups 3 to 12. They have unique properties that distinguish them from other elements and are crucial in complexation chemistry.
One of the defining features of transition metals is their ability to form variable oxidation states, which allows them to participate in a wide range of chemical reactions.
Another key feature is their formation of colored compounds, deeply related to the d-d transitions of electrons. This aspect not only has aesthetic importance but also aids in identifying the presence and type of transition metal complexes.

• Transition metals can form stable complexes with varying geometries such as octahedral, tetrahedral, and square planar.
• Their d orbitals can overlap with the orbitals of a cyanide ion, creating strong and diverse chemical bonds.
• Because of their ability to accept and donate electrons, these metals are perfect counterparts in forming complexes with ligands like CN⁻.

With these properties, transition metals play a crucial role in the complexation processes involving cyanide ions.

Chemical Bonding

Chemical bonding is a fundamental concept in chemistry that explains how atoms combine to form molecules. Within the realm of complexation chemistry, bonding also describes how ligands like cyanide ions interact with metal ions.
The bonding between a cyanide ion and a transition metal involves the donation of a lone pair of electrons from the cyanide ion to a vacant orbital in the metal ion. This process results in the formation of a coordinate covalent bond, which is distinct because the electrons in the bond originate entirely from the ligand, in this case, CN⁻.

• Coordinate covalent bonds are crucial in forming stable metal-ligand complexes and are different from typical ionic or covalent bonds.
• Cyanide ions are strong field ligands, meaning they can cause a large splitting of the metal ion’s d orbitals, impacting the magnetic and optical properties of the complex.

The understanding of chemical bonding, especially in the context of complexation, is essential for predicting how and why certain complexes form, such as those between cyanide ions and transition metals.