Problem 136 - A Complete Resource Book in Chemistry for JEE Main

Question

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

Step-by-Step Solution

Answer

The correct answer is (b) B, C.

Step 1: Understanding the Problem

We need to determine which set of properties from reducing, oxidizing, and complexing is exhibited by the cyanide ion (\(\mathrm{CN}^-\)) when it interacts with metal species.

Step 2: Analyzing the Cyanide Ion

Cyanide ion (\(\mathrm{CN}^-\)) is well known for its ability to form strong complexes with transition metals, making it a good complexing agent. It can form stable complexes, for example, with iron, resulting in compounds such as potassium ferricyanide.

Step 3: Determining Reducing and Oxidizing Properties

\(\mathrm{CN}^-\) is a weak reducing agent; it is not primarily known for oxidizing properties. While in rare reactions it may participate in electron transfer, the dominant ability is complexation rather than oxidation or significant reduction.

Step 4: Selecting the Correct Answer

Given the analysis of \(\mathrm{CN}^-\), it mainly exhibits complexing abilities with metals. Therefore, the properties shown by \(\mathrm{CN}^-\) concerning metals are complexing and, to a lesser extent, reducing, though primarily it is complexing.

Key Concepts

Cyanide Ion Properties

The cyanide ion, represented chemically as \( \text{CN}^- \), is an intriguing entity, particularly noted for its complexing capabilities when interacting with metals. Among its various attributes, its inclination to form stable complexes with metal ions stands out. However, aside from being a stellar complexing agent, understanding its other chemical properties—though less pronounced—is equally vital.- **Reducing Abilities**: The cyanide ion is considered a weak reducing agent. This means it has a limited capability to donate electrons in chemical reactions, contributing minimally to reducing other species. While not its forte, it does possess this characteristic, albeit not as prominently as its complexing properties.- **Oxidizing Properties**: Unlike stronger oxidizing agents, \( \text{CN}^- \) does not have significant oxidizing powers. It is not primarily used to gain electrons from other substances, making this property nearly negligible in most of its interactions, especially with metals.Overall, while the cyanide ion does show some reducing behavior in particular circumstances, its ability to form complexes is its most remarkable feature.

Transition Metal Complexes

Transition metals, found in the d-block of the periodic table, are renowned for their ability to form complexes. These metals possess unique attributes, especially when interacting with ligands like the cyanide ion. The core attributes that allow transition metals to form complexes include: - **Variable Oxidation States**: Transition metals can exhibit multiple oxidation states, enabling flexibility in bonding and facilitating the formation of various types of complexes. - **Empty d-Orbitals**: These metals have vacant d-orbitals that can accept electrons from ligands, fostering the creation of coordination compounds. These complexes are vital in various chemical and industrial processes, with **stability** being a key feature. The cyanide ion, being a strong ligand, often forms particularly robust complexes with transition metals. For instance, with iron, it forms a well-known stable compound, potassium ferricyanide. This affinity for bonding allows the cyanide ion to partake significantly in industrial applications and catalytic processes, showcasing the importance of transition metal complexes.

Ligand Interaction with Metals

In the realm of coordination chemistry, ligands are atoms, ions, or molecules that donate electron pairs to metals to form a complex. The cyanide ion is a potent example of a ligand interacting with metals, characterized by its ability to donate electron pairs to form stable complexes.Key aspects of ligand interaction include:- **Electron Donation**: Ligands, including \( \text{CN}^- \), act as Lewis bases, donating electron pairs to metal atoms or ions to form coordinate covalent bonds.- **Formation of Coordination Compounds**: The interaction between metals and ligands results in coordination compounds, which have diverse structures and properties, reliant on the nature of the metal and the ligand.The strength of the interaction primarily depends on the ligand's ability to donate electrons and the metal's ability to accept them. Cyanide ion, being a strong ligand, exhibits a preference for forming strong, stable complexes with transition metals.Such interactions are critical for understanding how complex ions behave in solution and are crucial in fields like bioinorganic chemistry and catalysis. These insights aid in the development of new materials and the advancement of various scientific fields.