My question is that- SF4 forms a see-saw shaped structure coz the 2 F atoms which are vertically bonded to S bent away from the lone pair due to repulsion. Then in ClF3 why don't the 2 vertically bonded F atoms bent away from 2 lone pairs?

Asked by divyakhare | 14th Sep, 2010, 12:00: AM

Expert Answer:

                                              
 
In ClF3, the chlorine atom has five electron-pairs in its outer shell; three of these are in Cl-F bonds, two are non-bonding ("lone") pairs. These(lone pairs) keep as far apart as possible, minimizing repulsion between each of the negatively charged clouds, by adopting T-shaped arrangement as the two lone pairs occupy equatorial positions at an angle of 120° to each other; this gives the lowest energy arrangement of the electron pairs in the molecule because repulsions involving lone pairs are stronger than those involving bond pairs, the F-Cl-F angle is a little under 180° so the molecule has a slightly bent T-shape. and the remaining space get covered by three fluorine atoms.  but that's not the case in the SF4 as only one lone pair and four bond pair are present in it.

Answered by  | 14th Sep, 2010, 08:47: PM

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