Can the following molecules be called meso compounds (cyclic structures which usually exist in non-planar forms)? In the planar form the following molecules have one plane of symmetry.However in
  the chair-form (the most stable form) for the first molecule and the non-planar form for the second molecule there is no plane of
  symmetry.Will the molecules still be called meso?


BTW I do not think the molecules ever attain completely planar form.

 





Just for quick reference I'm adding the non-planar forms of the two molecules.
These molecules can never be planar. There are no internal symmetry planes and therefore they are not meso.