While the barriers of rotation of the sp and ap rotamers of 9-(o-methylphenyl)fluorene, C(20)H(16), are sufficiently similar to permit them to equilibrate, both being observed (NMR) in solution, crystallization provides the sp rotamer, (I), exclusively. Although in the sp conformation the intramolecular distance between adjacent C atoms of the phenyl and fluorene rings is small [3.382 (4) A, within 0.02 A of the sum of the van der Waals radii], in the ap conformation the distance between the adjacent o-CH(3) group on the phenyl ring and C atom of the fluorene ring would be much closer, based on that exhibited in the crystalline ap progenitor 9-(o-methylphenyl)-9-fluorenol. The angle between the fluorene and 9-aryl planes of (I) is 75.82 (10) degrees.
Key indicatorsSingle-crystal X-ray study T = 296 K Mean '(C±C) = 0.004 A Ê R factor = 0.041 wR factor = 0.134 Data-to-parameter ratio = 14.6For details of how these key indicators were automatically derived from the article, see
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