First and most important: don't use FIST tool for chemical structures. This tool is faulty when it comes to chemical structure diagrams.
That's why I had to revert most of your edits that popped up on my Watchlist. Chemical structure diagrams are correctly placed in chemical structure (P117) not in image (P18), 3D diagrams should be in molecular model or crystal lattice model (P8224). In most of your edits you have added duplicated images which were already present in correct property.
In (±)-ADBICA (Q15708301) in you've added image that was not present and it was correct. This items describes a group of stereoisomers, your image shows one of the stereoisomers. So: you have to check every time that the image present in the Wikipedia article matches the item. In vinyldithiin (Q11330876) you've added an image that shows chemical reaction – it is not a correct image for an item describing a class of chemical compounds.
So, please (1) don's use FIST for chemistry-related items, (2) if you can't tell whether an image from the Wikipedia article is correct for the WD item, just leave it, there are other things to do here.