Difficult in grasping "the extent/limit of conformational space of a compound until it change its stereochemistry"

I have heard that a conformational landscape encompasses all conformers that a compound has for *a specific stereoisomer*. I think it makes sense *verbally*, because if all conformers of a stereoisomer include all conformers for all stereoisomers and one (mistakenly) designates those all stereoisomer conformations to be conformers for a specific stereoisomer, it will require an interconversion (or change in permutational position) of one or multiple bonds to be broken to make a different stereoisomer.


While it seems to make *verbal* sense to me, my visual thinking is really against this. Searching on Google, "stereoisomer conformation" and "conformer" are always treated as two different realms having no connection in between.


I feel there should be an image (or someone has done a research article about this) showing a conformational landscape with a functional group bonded to a particular atom, showing differences in spatial 3D position. It suffices to show that "this coordinate position is still the same stereoisomer" but that if the functional group is extended, whether freely translated or rotated in drawing to somewhere, it will make a different stereoisomer and *it is convincing enough that its stereochemistry interconversion will have to break some bonds first.*


Any example would be fine, but I prefer the case of cis-trans conversion of a cyclohexane in its chair conformation with few functional groups, because my visualization is that *its functional group stereochemistry interconversion still does not need bond breaking (but why it would have a different stereoisomer though?).*


Thus, here is the general question. **What is the extent or limit of conformational space of a molecule (or specifically, a particular stereoisomer) that is spatially unique to it, but if further extended to all random positional permutations will change its stereochemistry so that it will have to break some bonds first to let that interconversion happen?**




You have the right idea that conformational space can be partitioned by configurational isomers. The clearest cases are where you have to break bonds to end up with another configurational isomer, but that is actually not always the case. Atropisomerism also gives rise to different configurational isomers, even though they are just separated by a bond rotation with a very high barrier.


Your example with cyclohexane is actually a clear-cut case, since you really need to break bonds to switch from *cis* to *trans*. I visualized all possible chair conformations and the partitioning into configurational subspaces. There are [more conformers](https://chemistry.stackexchange.com/questions/32970/conformations-of-cyclohexane) that I left out for simplification.


[![Conformational space partitioning for cyclohexane-1,2-d2](https://i.stack.imgur.com/aE4AA.png)](https://i.stack.imgur.com/aE4AA.png)


If you still don't see why you need bond breaking, I recommend playing around with a molecular model kit.


In summary, the partitioning of conformers into distinct configurational isomers happens when they are interconverted by a process with a high barrier (*i.e.* bond breaking, hindered rotations, polytopal rearrangements, *etc.*).


 1