Crystal and molecular structure of syn-periplanar perchlorate of N(9-fluorenyl)-2-isopropyl-4,6-dimethylpyridinium

The structure of (C 23 H 24 N) + ClO 4 #75 is determined from single-crystal diffractometric data (R = 0.075 for 1532 independent reflections). The syn-periplanar conformation of the cation is confirmed. The dihedral angle between the planes of the pyridine ring and the fluorenyl nucleus is 79.4°. Rotation about the single bond C(sp 3 )-N + (sp 2 (bond length 1.51 A) requires serious deformation of the cation