[Oasis]

Could someone please explain to me what the enantiomers of 2,2-dichlorobicyclo[2.2.1]heptane would look like? Part of the question in my textbook was to determine the number of chirality centres, and I can understand that there are two, but then I can't seem to figure out what the enantiomers would look like. I know that two chirality centres would allow for a maximum of four stereoisomers, and the textbook says that there are only two because a trans arrangement of the one carbon bridge would be structurally impossible. I've made a model of the molecule, and I can't understand what a trans arrangement of the bridge would even look like, and I don't know how to connect it differently to make the two possible enantiomers. I think the enantiomer I have is the 1S, 4R enantiomer. If I try to manipulate the model to make the hydrogen atoms at the chirality centres point in the other direction, the model just snaps apart...I'm not sure if this occurrence is just a limitation of the model, or if it shows that the actual molecule couldn't be like that due to strain. It feels like the relative positions of the substituents must necessarily be in the form I have them in to maintain the ring and the bridge. Any help in describing what the enantiomers should look like would be appreciated.

[fledarmus]

Build two models, not just one. Make a model of the structure you have, then make a model of its mirror image. Now try to overlap them.

And no, a six membered ring is too small to bridge in a trans fashion, so there are only two possible stereoisomers of this compound.

If this doesn't answer the question, let me know and I will send a picture.