Problem 150 - A Complete Resource Book in Chemistry for JEE Main

Question

The type of isomerism present in nitropentaamine chromium (III) chloride is [2002] (a) ionization (b) optical (c) polymerization (d) linkage

Step-by-Step Solution

Answer

The type of isomerism is linkage isomerism.

Step 1: Identify the Compound

The compound in question is nitropentaamine chromium (III) chloride, written as \([Cr(NH_3)_5(NO_2)]Cl\). This includes a central metal atom, chromium, with coordination to five amine \((NH_3)\) groups and one nitro group \((NO_2)\).

Step 2: Analyze the Ligand Involved in Isomerism

The key ligand here is the nitro group \((NO_2)\). This ligand can link to the metal center through different atoms: nitrogen or oxygen, which is indicative of linkage isomerism.

Step 3: Understand Linkage Isomerism

Linkage isomerism occurs when a ligand can coordinate to the central metal using different atoms. For the nitro group, it can bind to chromium through the nitrogen atom, forming a nitro complex, or through an oxygen atom to form a nitrito complex.

Step 4: Conclusion

Since the nitro ligand in \([Cr(NH_3)_5(NO_2)]Cl\) can attach to the chromium atom in more than one way, the type of isomerism is linkage isomerism.

Key Concepts

Linkage Isomerism

When discussing coordination compounds, one fascinating aspect is linkage isomerism. This type of isomerism happens with certain ligands that have the ability to attach to the central metal atom through different atoms. In simpler terms, a ligand might have more than one donor atom that it can use to form a bond with the metal center. For example, let's consider the nitro group \(NO_2\).

The nitro ligand can form a bond with a metal either through the nitrogen atom, resulting in a nitro complex, or through one of the oxygen atoms, leading to a nitrito complex. This switch in connection alters how the ligand interacts with the metal and thus changes the properties of the compound. Therefore, identifying linkage isomers involves examining the different possibilities through which ligands can coordinate to a metal atom. Understanding linkage isomerism allows chemists to predict and manipulate the physical and chemical behaviors of coordination compounds.

Ligand Coordination

Ligand coordination refers to the way ligands, which are ions or molecules, bond with a central metal atom to form complexes. These ligands donate electron pairs to the metal, forming coordinate covalent bonds that help stabilize the metal atom. Coordination is crucial because it determines the structure, reactivity, and magnetic properties of the compound.

In coordination chemistry, each ligand uses its donor atom(s) to link with the central atom. For instance, in a complex like nitropentaamine chromium (III) chloride, the amine groups (\(NH_3\)) each use a nitrogen atom to connect to the chromium center. The nitro group (\(NO_2\)) also coordinates with the metal, but here is where linkage isomerism comes into play. Understanding the coordination details helps in characterizing the entire structure of such complexes.

Transition Metal Complexes

Transition metal complexes are chemical compounds consisting of a central transition metal atom bonded to surrounding ligands. These metals, found in the d-block of the periodic table, play a vital role in these complexes due to their unique electronic configurations that allow diverse bonding scenarios.

Such complexes are not only pivotal in understanding basic chemical principles but are also instrumental in industrial and biological processes. For example, hemoglobin, a complex containing iron, helps transport oxygen in blood. The coordination environment, defined by how ligand atoms are arranged around the metal, dictates many properties of the complexes. An understanding of these complexes, therefore, is essential to grasp the wide range of their practical applications.