# S-O bond length in SO2 and SO3 [duplicate]

Question: which molecule out of $\ce{SO2}$ and $\ce{SO3}$ has larger $\ce{S-O}$ bond length?
Both are $sp^2$ hybridised. Since $\ce{SO3}$ has more bond pair - bond pair repulsions, shouldn't $\ce{SO3}$ have more $\ce{S - O}$ bond length so it can reduce repulsion?
• I looked it up and $\ce{SO3}$ does have a slightly shorter bond than $\ce{SO2}$ which is indeed unusual. You should maybe add that fact to your question and you might draw a little more attention because your reasoning seems good to me. – jheindel Nov 12 '15 at 8:24
• Also related: molecular orbitals of $\ce{SO3}$ – Jan Nov 12 '15 at 9:42