Question

examine the molecule sf4 in the real molecules screen to check your prediction from question c. which interactions (bond-bond repulsion, lone-pair bond repulsion, lone pairlone pair repulsion) are more important in determining where the lone pair will go?

Answer 1

The lone pair on the sulfur atom in SF4 is placed in an equatorial position to minimize repulsions, resulting in a seesaw molecular structure, based on the principles of trigonal bipyramidal electron-pair geometry in which the lone pair occupies more space than bonding pairs.

Step-by-step explanation:

The molecular structure of sulfur tetrafluoride (SF4) is determined by the arrangement of electron pairs around the sulfur central atom. When examining SF4, we find that it has five regions of electron density which gives us a trigonal bipyramidal electron-pair geometry. There are four bonding pairs (BP) associated with the fluorine atoms and one lone pair (LP). In such structures, lone pairs take up more space than bonding pairs. This leads to greater lone pair-lone pair (LP-LP) and lone pair-bonding pair (LP-BP) repulsions.

Considering these repulsions, in a trigonal bipyramidal structure, it is most favorable to place the lone pair in an equatorial position rather than an axial one to minimize repulsive interactions. This results in two LP-BP repulsions at 90° in the equatorial position, compared to three at 90° if the lone pair were placed in the axial position. Therefore, the lone pair in SF4 occupies one of the equatorial positions, leading to a seesaw molecular structure.