Molecular structures of 3-[(2,2,3,3-tetrafluoro-propoxy)methyl]- and 3-[(2,2,3,3,3-pentafluoro-propoxy)methyl]pyridinium saccharinates

摘要

The salts 3-[(2,2,3,3-tetrafluoropropoxy)methyl]pyridinium saccharinate, C_9H_10-F_4NO~+·C_7H_4NO_3S~-, (1), and 3-[(2,2,3,3,3-pentafluoropropoxy)methyl]pyri-dinium saccharinate, C_9H_9F_5NO~+·C_7H_4NO_3S~-, (2), i.e. saccharinate (or 1,1-di-oxo-1λ~6 ,2-benzothiazol-3-olate) salts of pyridinium with -CH_2OCH_2CF_2CF_2H and -CH_2OCH_2CF_2CF_3 meta substituents, respectively, were investigated crystallographically in order to compare their fluorine-related weak interactions in the solid state. Both salts demonstrate a stable synthon formed by the pyridinium cation and the saccharinate anion, in which a seven-membered ring reveals a double hydrogen-bonding pattern. The twist between the pyridinium plane and the saccharinate plane in (2) is 21.26 (8)° and that in (1) is 8.03 (6)°. Both salts also show stacks of alternating cation-anion pi-interactions. The layer distances, calculated from the centroid of the saccharinate plane to the neighbouring pyridinium planes, above and below, are 3.406 (2) and 3.517 (2) A in (1), and 3.409 (3) and 3.458 (3) A in (2).