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

(b) diammine(ethylenediamine)ruthenium (II) nitrate.

Step 1: Identify Components of the Complex

The complex given is \( [\mathrm{Ru}(\mathrm{NH}_{3})_{2}(\mathrm{en})(\mathrm{NO}_{3})_{2}] \). It consists of ruthenium (Ru), two ammine groups (\(\text{NH}_3\)), one ethylenediamine (en) ligand, and two nitrate groups (\(\text{NO}_3^-\)). Ammine and ethylenediamine are neutral ligands, while nitrate is an anionic ligand.

Step 2: Determine Oxidation State of Ruthenium

To find the oxidation state of Ru, consider the overall charge of the complex. Since there is no charge indicated, the complex is neutral. Set the unknown oxidation state of Ru as \( x \). The equation is: \( x + 0 + 0 - 2 = 0 \), where both \(\text{NH}_3\) and \(\text{en}\) are neutral (0 charge), and each nitrate has a charge of -1. Solving gives \( x = +2 \). Therefore, the oxidation state of Ru is +2.

Step 3: Name the Ligands

Name the ligands in increasing order of importance: Ammine for \(\text{NH}_3\), ethylenediamine for en, and nitrate for \(\text{NO}_3^-\). In IUPAC nomenclature, neutral ligands like ammine and en precede anionic ligands like nitrate. Order them alphabetically: ammine < ethylenediamine < nitrate.

Step 4: Write the IUPAC Name

Following IUPAC rules, write the name starting with the ligand names in alphabetical order, followed by the central metal with its oxidation state in Roman numerals. Since there are two ammine ligands, use 'diammine', for one en ligand, use '(ethylenediamine)', and for two nitrate groups, simply mention 'nitrate'. Combine to form: diammine(ethylenediamine)ruthenium(II) nitrate.

Key Concepts

Coordination Compounds

Coordination compounds are a fascinating class of compounds where a central metal atom or ion is bonded to a number of surrounding molecules or ions, known as ligands. These are crucial in many biological systems and industrial applications. The coordination center, usually a transition metal like ruthenium in our example, is surrounded by ligands which can be neutral or carry charges. This unique structure imparts special properties and reactivity.
Coordination compounds are significant due to their complex structures and the ability to form bonds with a variety of ligands. They can exhibit isomerism, where compounds with the same formula can have different arrangements of atoms. The nature and arrangement of ligands can dramatically affect the properties and color of these compounds.

• A central metal atom or ion.
• Surrounding molecules or ions called ligands.
• Ability to form complex structures and exhibit isomerism.

Ligands

Ligands are the molecules or ions that bind to the central metal in a coordination compound. They are critical in determining the chemical behavior of coordination compounds. Ligands can be either neutral molecules or ions that donate an electron pair to the metal atom or ion.
Different types of ligands include neutral ligands like ammonia (\(\text{NH}_3\)) and ethylenediamine (en), which do not carry a charge, and anionic ligands such as nitrate (\(\text{NO}_3^-\)). These entities directly affect the stability and reactivity of the coordination compound.

• Neutral Ligands: Do not carry a charge (e.g., \(\text{NH}_3\), en).
• Anionic Ligands: Carry a negative charge (e.g., \(\text{NO}_3^-\)).

Oxidation States

The concept of oxidation states is integral in understanding coordination compounds. It helps determine the distribution of electrons and the chemical behavior of the metal center. The oxidation state is calculated based on the charges contributed by the ligands and the overall charge of the compound.
In the complex \([ ext{Ru}( ext{NH}_3)_2( ext{en})( ext{NO}_3)_2]\), we calculated the oxidation state of ruthenium (Ru) by considering neutral ligands (\( ext{NH}_3\) and en) which contribute zero charge, and the anionic ligands (\( ext{NO}_3^-\)), which each contribute a negative charge.Therefore, our calculation showed that Ru exhibits an oxidation state of +2.

• Oxidation state helps predict the compound's reactivity.
• Calculated using the charge contributions of ligands and the overall charge.

Neutral and Anionic Ligands

Neutral ligands and anionic ligands play a key role in shaping the characteristics of coordination compounds. Understanding their different roles is essential.
Neutral ligands, such as \( ext{NH}_3\) and ethylenediamine, do not add to the net charge of the coordination complex. They primarily influence the geometry and stability of the compound through their electron donation.
In contrast, anionic ligands like \( ext{NO}_3^-\) contribute to the overall charge and directly influence the oxidation state of the metal center. This can alter the compound's reactivity and interaction with other substances.

• Neutral Ligands: Affect stability and geometry, contribute zero charge.
• Anionic Ligands: Influence oxidation states, affect compound charge and reactivity.