The salts 3-[(2,2,3,3-tetrafluoropropoxy)methyl]pyridinium saccharinate, C9H10F4NO+·C7H4NO3S−, (1), and 3-[(2,2,3,3,3-pentafluoropropoxy)methyl]pyridinium saccharinate, C9H9F5NO+·C7H4NO3S−, (2), i.e. saccharinate (or 1,1-dioxo-1λ6,2-benzothiazol-3-olate) salts of pyridinium with –CH2OCH2CF2CF2H and –CH2OCH2CF2CF3
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 π-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) Å in (1), and 3.409 (3) and 3.458 (3) Å in (2).
3-[(2,2,3,3-四氟丙氧基)甲基]吡啶鎓糖精盐,C9H10F4NO+-C7H4NO3S-,(1)和 3-[(2,2,3,3,3-五氟丙氧基)甲基]吡啶鎓糖精盐,C9H9F5NO+-C7H4NO3S-,(2),即或 1,1-二氧代-1λ6,2-苯并噻唑-3-醇)吡啶鎓的糖精盐,分别带有 -CH2OCH2CF2CF2H 和 -CH2OCH2CF2CF3
元取代基的吡啶鎓盐进行了晶体学研究,以比较它们在固态中与氟有关的弱相互作用。这两种盐都显示了由吡啶阳离子和糖精阴离子形成的稳定合子,其中的七元环显示了双氢键模式。在(2)中,吡啶鎓平面与糖醛酸平面之间的扭曲度为 21.26 (8)°,而在(1)中则为 8.03 (6)°。这两种盐还显示出阳离子-阴离子π相互作用的交替堆叠。从糖醛酸平面的中心点到邻近的吡啶平面(上部和下部)的层间距计算,(1) 中为 3.406 (2) Å 和 3.517 (2) Å,(2) 中为 3.409 (3) Å 和 3.458 (3) Å。