atropisomers

https://doi.org/10.1351/goldbook.A00511
A subclass of conformers which can be isolated as separate chemical species and which arise from restricted rotation about a single bond, e.g. ortho-substituted biphenyl, 1,1,2,2-tetra-tert-butylethane.
See: rotational barrier
Source:
PAC, 1996, 68, 2193. 'Basic terminology of stereochemistry (IUPAC Recommendations 1996)' on page 2200 (https://doi.org/10.1351/pac199668122193)