Question

Identify the incorrect statement.

• A. \( \text{PEt}_3 \) and \( \text{AsPh}_3 \) as ligands can form \( d\pi \)-\( d\pi \) bond with transition metals
• B. The \( \text{N} - \text{N} \) single bond is as strong as the \( \text{P} - \text{P} \) single bond
• C. Nitrogen has unique ability to form \( p\pi \)-\( p\pi \) multiple bonds with nitrogen, carbon and oxygen
• D. Nitrogen cannot form \( d\pi \)-\( p\pi \) bond as other heavier elements of its group

Answer 1

The Correct Option is B

To identify the incorrect statement, let's analyze each option with respect to chemical bonding concepts:

1. \( \text{PEt}_3 \) and \( \text{AsPh}_3 \) as ligands can form \( d\pi \)-\( d\pi \) bond with transition metals:
   • \( \text{PEt}_3 \) and \( \text{AsPh}_3 \) are known to act as ligands due to their ability to donate lone pairs from phosphorus and arsenic atoms respectively. They can participate in back-bonding with the \( d \)-orbitals of transition metals, facilitating \( d\pi \)-\( d\pi \) interactions.
   • This statement is correct because such phosphorus and arsenic ligands are capable of forming \( d\pi \)-\( d\pi \) bonds with transition metals.
2. The \( \text{N} - \text{N} \) single bond is as strong as the \( \text{P} - \text{P} \) single bond:
   • Nitrogen forms single bonds that are generally weaker than phosphorus single bonds due to nitrogen's smaller size, leading to greater electron-electron repulsion and less effective orbital overlap.
   • The \( \text{N} - \text{N} \) bond dissociation energy is about 163 kJ/mol, while the \( \text{P} - \text{P} \) bond is stronger at around 201 kJ/mol.
   • This statement is incorrect as it incorrectly compares the bond strengths.
3. Nitrogen has unique ability to form \( p\pi \)-\( p\pi \) multiple bonds with nitrogen, carbon, and oxygen:
   • Nitrogen can form strong \( p\pi \)-\( p\pi \) bonds due to its small atomic size and high electronegativity, facilitating overlap of \( p \)-orbitals. This is evident in structures like \( \text{N}_2 \), \( \text{C} \equiv \text{N} \), and \( \text{N}=\text{O} \).
   • This statement is correct as nitrogen's ability to form such bonds is well-documented.
4. Nitrogen cannot form \( d\pi \)-\( p\pi \) bond as other heavier elements of its group:
   • Nitrogen lacks readily available \( d \)-orbitals for \( d\pi \)-\( p\pi \) bonding, unlike its heavier congeners like phosphorus which can utilize \( d \)-orbitals.
   • This statement is correct since nitrogen’s typical electronic configuration does not allow \( d\pi \)-\( p\pi \) bonding.

Conclusion: The incorrect statement is "The \( \text{N} - \text{N} \) single bond is as strong as the \( \text{P} - \text{P} \) single bond."