# SF3Cl Vsepr Most stable structure

I was asked to " Use VSEPR theory to predict the most stable structure for $\ce{SF3Cl}$ and justify your answer. "

I managed to interpret the structure as seesaw and with a lone pair on the equatorial position. However, I had chosen that the most stable structure was that with Chlorine on the equatorial position because I thought that the Chlorine-Sulfur bond length would be greater than that of Chlorine-Fluorine.

However, the answer key stated the Fluorine was more electronegative, and therefore would be more stable on the axial (with chlorine as equatorial).

I was wondering if the answer key was accurate and if so, how would I compare the effects of electronegativity and bond length? I had considered electronegativity but I had thought it would simply make the bond even shorter, increasing repulsion.

Thanks!

The bond lengths have little to do with the stability of the atom positioning around the central $\ce{S}$ atom. Rather, the relative sizes of the electron clouds are what should be considered when positioning these atoms. An atom of $\ce{Cl}$ has a 8 more electrons than does an atom of $\ce{F}$, so naturally its electron cloud will be larger and therefore more repulsive. The $\ce{Cl}$ should therefore be positioned in the equatorial position for the same reason you predicted that the lone pair would be present in the equatorial position--because these positions offer the least repulsion between the electron clouds of the atoms.