Chlorine trifluoride shape

2010-11-05 10:07 pm

Why it is T-shaped?
Can you explain the following. Thanks.
ClF3 is approximately T-shaped, with one short bond (1.598 Å) and two long bonds (1.698 Å). This structure agrees with the prediction of VSEPR theory, which predicts lone pairs of electrons as occupying two equatorial positions of a hypothetic trigonal bipyramid. The elongated Cl-Faxial bonds are consistent with hypervalent bonding.

更新1:

Why it is not trigonal planar with each bond angle = 120 ?

回答 (1)

己式庚辛

2010-11-06 6:12 am

✔ 最佳答案

the lone pair-bond pair repulsion is stronger than the bond pair-bond pair repulsion.

consider the central chlorine atom. for its totally 7 valence electrons, 3 are used to form Cl-F bonds with fluorine, remaining 4 electrons in two lone pairs.

now, 3 bond pairs, 2 lone pairs.
bond angle between axial-equatorial is 90 degrees, bond angle between equatorial-equatorial is 120 degrees.
repulsion due to axial-equatorial will be Greater than repulsion due to equatorial-equatorial.

if it's trigonal planar, then the lone pairs are placed at axial positions.
then, there'll be 6 lone pair-bond pair repulsion at 90 degrees.

if it's T-shape, the the lone pairs are placed at equatorial positions.
then, there'll be 4 lone pair-bond pair repulsion at 90 degrees.

to minimize repulsion, T-shape is preferred and adopted.

👍 0 👎 0