to permit refinement in Pn21a. In the straight channel an approximate mirror plane through N and the channel axis, perpendicular to the crystallographic mirror plane, exists. The tetrapropylammonium ion lies at the intersection of the straight and sinusoidal channels in two different orientations. The two orientations, populated in a ratio of 3:2, are nearly related by the approximate mirror plane. Contrary to literature data the propyl-N-propyl fragments pointing into the sinusoidal and straight channel, respectively, both have CNCC torsion angles around 60 °. No evidence is obtained for the tetrapropylammonium ion breaking the rn symmetry and extra disorder around rn is assumed. The mean C-C and C-N distances and mean CCC, CCN and CNC angles, averaged over both ions, are 1.55 and 1.57 A and 109, 113 and 109 °, respectively. Contact distances smaller than 4.0/~, between terminal C atoms of adjacent template ions, are in the range 3.56 (7)-3.75 (2) ~.

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