homotopic

Atoms or groups of a molecule which are related by an n-fold rotation axis (n = 2, 3, etc.) are called homotopic. For example, chiral tartaric acid ( axis), chloroform ( axis) and cyclohexaamylose (α-cyclodextrin, axis) have respectively two homotopic carboxyl groups, three homotopic chlorine atoms and six homotopic d-glucose residues.