Chimie générale avancée I

We are aware that the solution for exercise 7.2(b) has caused some confusion.

According to what you have learned in the lectures, the most stable lewis structure is with all the charges minimised, and sulfur can expand it’s octet, so the most stable lewis structure would be O=S:=O (bent). 

There is also a resonance structure O-S:=O, with a negative charge on oxygen and positive charge on sulfur. From experimental observation of bond lengths, we can see that these resonance structures actually predominate. This is because of the increased electron delocalisation which lowers the energy of the structure.

HOWEVER, it would be impossible to predict this without experimental data or computation. Therefore ignore this question and it will not come up in the exam, stick to the methods you learnt in class to determine lewis structures. The question will be removed from next year's exercises.

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