Question

In triplet carbenes, the two electrons (1) are paired in one orbital (2) are present in different orbitals (3) have the same spin (4) both \(\mathrm{b}\) and \(\mathrm{c}\)

Short answer

The correct answer is option (4).

Step-by-step solution

Understand Carbenes

Carbenes are neutral divalent carbon species with two unshared valence electrons.

Define Triplet Carbenes

Triplet carbenes have two electrons with parallel spins residing in separate orbitals, making them paramagnetic.

Analyze Electron Configuration

In triplet carbenes, the electrons are not paired. Instead, they occupy different orbitals and possess the same spin.

Identify Correct Statements

From the options given, (2) 'are present in different orbitals' and (3) 'have the same spin' accurately describe the electron configuration of triplet carbenes.

Final Answer

Thus, the correct answer is option (4), which includes both (2) and (3).

Key concepts

carbenes

Carbenes are fascinating yet simple molecules in organic chemistry. They contain a carbon atom with only two bonds, leaving the carbon with two unused valence electrons. This unique configuration gives carbenes special properties.
For clarity:

• Carbenes have a central carbon atom with two sigma bonds and two valence electrons.
• They are usually represented by the formula \text{R}-\(\text{C}\):\(\text{R}\).

The two valence electrons can occupy one orbital as a pair, leading to what is known as a singlet carbene. Alternatively, each electron can occupy separate orbitals with parallel spins, resulting in a triplet carbene. This electron configuration directly influences their chemical reactivity and magnetic properties.
There are two main types:

• Singlet carbenes: Electrons are paired in one orbital.
• Triplet carbenes: Electrons are unpaired in separate orbitals with parallel spins.

Understanding the nature of carbenes is essential for grasping their reactions and behavior in various chemical processes.

electron configuration

The electron configuration of atoms and molecules describes how their electrons are distributed in different orbitals. This helps predict the chemical behavior and properties of the substance. For triplet carbenes, the electron configuration is quite specific. In triplet carbenes:

• The two valence electrons are in different orbitals.
• Both electrons have the same spin (parallel spins).

This specific arrangement explains the magnetic properties of triplet carbenes. Instead of being paired in one orbital, the electrons remain unpaired in two separate ones, which is a key distinction between singlet and triplet carbenes. To better understand, consider the following:

• In singlet carbenes, both electrons would pair up in one orbital, resulting in no net spin.
• In triplet carbenes, each electron occupies its own orbital, resulting in a magnetic moment due to their parallel spins.

This difference is critical as it affects how carbenes interact with other molecules and their overall reactivity.

paramagnetism

Paramagnetism refers to the magnetic properties of materials with unpaired electrons. These materials are attracted to external magnetic fields. Triplet carbenes exhibit paramagnetism due to their unique electron configuration:

• They have unpaired electrons in separate orbitals.
• These unpaired electrons have parallel spins.

The presence of unpaired electrons creates a magnetic moment, making triplet carbenes magnetic. Contrast this with singlet carbenes, which do not show paramagnetism since their electrons are paired. Additionally, paramagnetism is a broader concept and applies to many other types of atoms and molecules with unpaired electrons. Here's a further breakdown:

• Only substances with unpaired electrons can be paramagnetic.
• When exposed to a magnetic field, the spins of the unpaired electrons align with the field.

In essence, understanding paramagnetism is crucial for distinguishing between different types of chemical species and predicting their magnetic behavior.