| Structure of Nonactin-Calcium Perchlorate, $C_{40}H_{64}O_{12}.Ca(ClO_{4})_{2}$, and a Comparative Study of Metal-Nonactin Complexes (1983) | |||||||||
Abstract | |||||||||
| $M_r = 975.9$, orthorhombic, Pnna, a = 20.262 (3), b = 15.717 (2), $c = 15.038 (1) \AA$, $V = 4788.97 \AA^3$, z = 4, $D_ x = 1.35 Mg m ^-{3}$, $CuK\alpha$ radiation, $\lambda = 1.5418 \AA$, $\mu = 2.79 mm^{-1}$, F(000) = 2072, T = 293 K, R = 0.08, 3335 observed reflections. The molecular structure and the crystal packing are similar to those observed in the nonactin complexes of sodium thiocyanate and potassium thiocyanate. The eight metal-O distances are nearly the same in the potassium complex whereas the four distances involving carbonyl O atoms are shorter than the remaining four involving the tetrahydrofuran-ring O atoms in the Na and the Ca complexes. This observation can be explained in terms of the small ionic radii of $Na^+$ and $Ca^{2+}$, and leads to a plausible structural rationale for the stronger affinity of nonactin for $K^+$ than for the other two metal ions. | |||||||||
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