Alkali-Metalated Forms of Thiacalix[4]arenes

The alkali metal salts [TCALi4] (1), [TCANa4] (2), and [TCALK4] (3) of fully deprotonated p-tert-butyltetrathiacalix[4]arene (H4TCA) are readily available from the reactions of thiacalix[4]arene and n-BuLi, NaH, or KH as deprotonating
reagents. Crystals of the sodium salts 2 and the potassium salt 3 suitable for X-ray diffraction were obtained in the
form of the pyridine solvates [(TCA)2Na8·8py] (2·8py) and [(TCA)2K8·8py] (3·8py). These molecules are dimers in
the solid state but are structurally not related. In addition, the reaction of H4TCA and lithium hydroxide afforded the
structurally characterized complex [(TCA)Li5(OH)·4THF] (4). The molecular structure of 4 as well as the structures
of 2·8py and 3·8py reveal a close relationship to the corresponding alkali metal salts of the calix[4]arenes.