%0 Journal Article
%T meso-4,4¡ä-Difluoro-2,2¡ä-{[(3aR,7aS)-2,3,3a,4,5,6,7,7a-octahydro-1H-1,3-benzimidazole-1,3-diyl]bis(methylene)}diphenol
%A Augusto Rivera
%A Diego Quiroga
%A Jaime R¨ªos-Motta
%A Monika Ku£¿erakov¨¢
%J Acta Crystallographica Section E
%D 2013
%I International Union of Crystallography
%R 10.1107/s1600536813000305
%X In the crystal structure of the title compound, C21H24F2N2O2, there are two intramolecular O¡ªH...N hydrogen bonds involving the N atoms of the imidazolidine ring and the hydroxy groups. The crystal studied was a meso compound obtained by the reaction of the aminal (2S,7R,11S,16R)-1,8,10,17-tetraazapentacyclo[8.8.1.18,17.02,7.011,16]cosane with 4-fluorophenol. The imidazolidine ring has a twisted conformation with a CH¡ªCH¡ªN¡ªCH2 torsion angle of 44.99 (14)¡ã and, surprisingly, the lone pairs of the N atoms are disposed in a syn isomerism, making the title compound an exception to the typical `rabbit-ear effect' in 1,2-diamines. In the crystal, molecules are linked via C¡ªH...F hydrogen bonds, forming chains along the c-axis direction. These chains are linked via another C¡ªH...F hydrogen bond, forming a three-dimensional network.
%U http://scripts.iucr.org/cgi-bin/paper?S1600536813000305