Disorder in the Crystal Structures of Pseudosymmetrical Amino-Phenylbenzothiazoles
摘要
A series of 2α, 2β, 3, 4β polymorphs of 2-, 3-, 4-aminophenylbenzothiazoles (2-pbt, 3-pbt, 4-pbt) is studied by XRD. The polymorphs crystallize in polar space groups. Static orientational disorder in their crystal structures is described. The disorder is a consequence of two factors: 1) presence of pseudosymmetry D2h in the molecules; 2) absence of strong specific intermolecular interactions. The type of symmetry transformation relating disordered positions and the disorder degree are specific to each polymorph. The highest and lowest minor position occupancies are exhibited by 2α (30%) and 2β (2%), respectively. In the case of 2-pbt polymorphs, the assumption of dynamic or static disorder caused by the intramolecular transfer of the amino group′s H atom to the heterocyclic fragment′s N atom is rejected.