Problem 54 - A Complete Resource Book in Chemistry for JEE Main

Question

The IUPAC name for \(\left[\mathrm{Ru}\left(\mathrm{NH}_{3}\right)_{2}(\mathrm{en})\left(\mathrm{NO}_{3}\right)_{2}\right]\) is (a) diammine(ethylenediamine) nitratoruthenium(III) (b) diammine(ethylenediamine)ruthenium (II) nitrate (c) diamminebis(ethylenediamine) ruthenium(III) nitrate (d) (ethylenediamine) diamineruthenium(II)nitrate

Step-by-Step Solution

Answer

The IUPAC name is (b) diammine(ethylenediamine)ruthenium (II) nitrate.

Step 1: Identify the Ligands

Examine the complex compound \([{\mathrm{Ru}}(\mathrm{NH}_{3})_{2}(\mathrm{en})(\mathrm{NO}_{3})_{2}]\). The ligands present are two ammine groups \((\mathrm{NH}_3)\), one ethylenediamine \((\mathrm{en})\), and two nitrate groups \((\mathrm{NO}_3)_{2}\).

Step 2: Determine the Coordination Number

Ammine \((\mathrm{NH}_3)\) is monodentate and contributes two coordination sites. Ethylenediamine \((\mathrm{en})\) is bidentate and contributes two coordination sites. Nitrate \((\mathrm{NO}_3)\) is also monodentate and contributes two coordination sites. Therefore, the total coordination number is 6.

Step 3: Determine the Oxidation State of Ruthenium

Let the oxidation state of Ruthenium be \(x\). Since \(\mathrm{NH}_3\), \(\mathrm{en}\), and \(\mathrm{NO}_3^{-}\) ligands are neutral, and \(\mathrm{NO}_3\) is \(-1\), the equation will be \(x + 0 + 0 - 2 = 0\). Solving for \(x\) gives \(x = +2\). Thus, the oxidation state of ruthenium is +2.

Step 4: Assign the IUPAC Name

As the ligands are named alphabetically, 'diammine' comes before '(ethylenediamine)'. The prefix 'di-' in 'diammine' indicates the presence of two \(\mathrm{NH}_3\) ligands. The name for this complex with Ruthenium in the +2 oxidation state is: diammine(ethylenediamine)ruthenium(II) nitrate.

Key Concepts

Complex Compounds

In chemistry, complex compounds are fascinating structures where at least one metal ion is bound to a group of atoms, known as ligands. These compounds are characterized by their unique arrangements, leading to diverse chemical behaviors. Complex compounds are crucial in various fields, including biochemistry, materials science, and industrial chemistry.

When discussing complex compounds, it is essential to remember that they are not simply mixtures of molecules. The metal-ligand bonds form a stable entity, often referred to as a coordination complex. A key aspect determining their properties is how the metal ion interacts with the ligands. This interaction dictates the complex's stability and reactivity.

• Stable structures due to coordinate bonds
• Variety in function and application due to diverse metal and ligand types
• Central to the understanding of molecular architecture and function

Understanding these nuances provides insight into the complexity and utility of these chemical structures.

Coordination Chemistry

Coordination chemistry is the study of compounds with a central metal ion bonded to surrounding molecules or ions, known as ligands. This field explores how these interactions affect the properties and behavior of the complex.

Coordination complexes are described by coordination number, geometry, and the nature of the ligands. These aspects influence a compound's color, magnetism, and reactivity. For example, coordination chemistry explains how the unique tetrahedral or octahedral arrangements of ligands around a metal ion result in different chemical and physical properties.

• Deals with metal-ligand binding
• Affects compounds' chemical and physical traits
• Important for understanding molecular geometry

Coordination chemistry is vital for designing new materials and understanding biological systems, where metal ions play a crucial role.

Oxidation State

The oxidation state in chemistry is a way of keeping track of electrons in atoms. In a complex compound, it helps determine how many electrons a metal ion has gained or lost during bond formation.

Assigning the oxidation state is crucial in naming complexes using IUPAC nomenclature. By knowing it, one can decipher the metal ion's charge in the complex. This information is often derived from the charge of ligands and the overall neutrality of the compound. For example, in the complex \([\text{Ru}( ext{NH}_3)_2( ext{en})( ext{NO}_3)_2]\), the oxidation state of Ruthenium is +2, calculated by balancing the charges of the ligands and the complex.

• Indicator of electron distribution
• Vital for naming and understanding complex compounds
• Helps determine the metal ion's role in reactivity

Understanding oxidation states aids in predicting chemical reactions and forming stable complex compounds.

Ligands

Ligands are molecules or ions that donate an electron pair to bond with a central metal atom in a complex. They significantly influence the behavior and stability of coordination compounds through their nature and number.

Ligands can be classified based on their charge, size, and the number of donor atoms available to bond with the metal. Common types include:

• Monodentate ligands: e.g., NH\(_3\) and NO\(_3^-\), attaching through a single donor atom.
• Bidentate ligands: e.g., ethylenediamine (en), attaching through two donor atoms.
• Polydentate ligands: those which attach through multiple donor atoms.

These tiny differences lead to significant changes in the properties of the coordination compounds, like their geometry and reactivity. Understanding ligands is crucial to predict and tune the properties of the resulting complexes.

Coordination Number

The coordination number represents the number of ligand bonds formed with the central metal atom or ion in a coordination complex. It plays a critical role in determining the spatial arrangement and geometry of a complex.

For example, a coordination number of 6 often leads to an octahedral geometry, while a coordination number of 4 might suggest a tetrahedral or square planar geometry. Calculating the coordination number involves counting the number of donor atoms bonded to the central atom. In the example \([\text{Ru}( ext{NH}_3)_2( ext{en})( ext{NO}_3)_2]\), the total coordination number is 6, derived from the contributions of its ligands.

• Determines the geometry of the complex
• Derived from the total number of bonds to the central atom
• Influences the compound's structural and electronic properties

Understanding the coordination number is essential for predicting the shape and reactivity of coordination compounds.