Jm. Harrowfield et al., ALKYLAMMONIUM CATION INTERACTIONS WITH CALIXARENE ANIONS .2. STRUCTURAL CHARACTERIZATION OF A SALT OF 2-3 CATION - CALIXARENE STOICHIOMETRY, Perkin transactions. 2, (1), 1994, pp. 5-9
A room temperature single crystal X-ray structure determination on the
tetramethylammonium 'salt' of calix[4]arene ([1.1.1.1]metacyclophane-
7,14,21,28-tetraol) has revealed an unusual stoichiometry and unusual
structure for this compound. Crystals of salt are tetragonal, space gr
oup P4/nnc, a = 18.230(4), c = 22.897(6) angstrom, Z = 4 f.u.; the str
ucture was refined to a residual of 0.087 for 1471 'observed' [I > 3si
gma(I)] reflections. The solid has the composition LH4.2[NMe4]+[LH3]-.
H2O (LH4 = calix[4]arene) and contains the cation, 'C', in two distinc
t environments, both involving inclusion within the calixarene units b
ut one involving simple inclusion by a single calixarene ('A') and the
other encapsulation by a facing pair of symmetry-related calixarene e
ntities ('B'). Interaggregate spacings by lattice water molecules, W,
result in the 'A' moieties being stacked up the 4 axis ... WACCAW ...
while the 'B' moieties are stacked along the 2 axes in the ab diagonal
, ... W'BCBW'.