Out of curiosity, I've tried to run Am1 on scyllo- and myo-inositol, and if software is any credible, then
- The difference is only 1/4 kcal. If an easy deformation had permitted to go from one to the other, the room temperature would do it.
- Scyllo has indeed a lower heat of formation. This is for one single molecule alone in vacuum, not for a solid, and details like the positions of hydrogens can flip the comparison.
- Oxygens look a tiny bit farther apart with just one axial. Not uncommon, and it sounds rather logic to me.
- A second axial oxygen at para location to the first one and to the other face of the cyclohexane gains 1/2 kcal further.
- Notice that Wiki claims: "myo is more stable in chair", not "myo is more stable than scyllo".
Screenshot attached, log in to see it.