Inorganic Chemistry> phosohorous pentachloride...

In PCl5 axial bonds are longer than equitorial bonds not in PF5. why?

deeksha sharma , 15 Years ago

Grade 11

5 Answers

aditya suman

Last Activity: 15 Years ago

in pcl5 the axial bonds suffer repulsion from the equatorial bonds so they become long and weak but in pf5 the axial and equatorial bonds are of nearly equal length because the repulsion between the bonds tries to make axial bonds longer but fluorine being most electronegative makes the P-F bond shorter as a result axial bonds become nearly equal to equatorial bonds.

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pradeep

Last Activity: 10 Years ago

i disagree with the answers posted already as far as i know in case of PF5 axial F atoms exchange their positions with equitorial F atoms which is not the case for PCl5 hence in PCl5 due to different repulsions for axial and equitorial Cl atoms their bond length changes while for PF5 as axial and equitorial F atoms exchange their positions frequently so their bond length remains same, similar to the concept of resonance in which we have hybrid structure with all bond lengths same.

Anujay Singh

Last Activity: 8 Years ago

All bonds of the molecule PF₅ are equal because of Berry Pseudorotation. All the F atoms interchange among each other continuously at a very fast speed so the bond lengths are considered to be equal.

Atul

Last Activity: 7 Years ago

According to NMR studies it is proved that axial and equatorial bond are equal and this research is done on very microscopic level

Rishi Sharma

Last Activity: 5 Years ago

Dear Student,
Please find below the solution to your problem.

In pcl5 the axial bonds suffer repulsion from the equatorial bonds so they become long and weak but in pf5 the axial and equatorial bonds are of nearly equal length because the repulsion between the bonds tries to make axial bonds longer but fluorine being most electronegative makes the P-F bond shorter as a result axial bonds become nearly equal to equatorial bonds.

Thanks and Regards