Question

Consider X, molecules for which X = B, C, N, O and F. Which of the following observations provides
experimental evidence for the so-called o-n crossover?
Select one:​

Answer 1

* The question was incomplete. Below you will find the missing content.*

Q. Consider X₂ molecule for which X = B, C, N, O and F. Which of the following observations provides experimental evidence for the so-called σ-π crossover?

a) N₂ is diamagnetic

b) F₂ is diamagnetic

c) B₂ is paramagnetic

d) O₂ is paramagnetic

ANSWER:

B₂ is paramagnetic.

EXPLANATION:

• B₂ molecule is formed by overlapping of 2 boron atom.
• two boron atom are bonded by covalent bond.
• Energy level of boron molecule= { (σ2s)² (σ*2s)² (π2px)¹ (π*2py)¹.
• Boron has one 2s orbital and three 2p orbital.
• The 2s orbital will overlap and form 2sσ and 2sσ* orbitals.
• 2px orbital will overlap and will form 2pσ and 2pσ* orbital.
• 2py and 2pz will overlap to form pairs of 2pπ and 2pπ*.
• The order of energy will be :

2sσ < 2sσ* < 2pπ < 2pσ <2pπ* < 2pσ*

• no. of antibonding orbital = 2 and bonding orbital = 4, therefore Bond order = 1
• Since (π2px) and (π*2py) has unpaired electron therefore B₂ is paramagnetic.

CONCLUSION

option (c). B₂ is paramagnetic is correct.

#SPJ2