title: A monoclinic polymorph of (R,R)-4,4'-dibromo-2,2'-[cyclo-hexane-1,2-diylbis(nitrilo-methanylyl-idene)]diphenol.
abstract: The title compound, C(20)H(20)Br(2)N(2)O(2), a tetra-dentate Schiff base, is the enanti-omerically pure R,R-diastereomer of four possible stereoisomers. The mol-ecular structure reveals two strong intra-molecular O-H⋯N hydrogen bonds between the hy-droxy O atom and the imino N atom, which each generate S(6) rings. In the crystal, mol-ecules are stacked in columns along the a axis; when viewed down the b axis, successive columns are stacked in the opposite direction. The structure reported herein is the monoclinic polymorph of the previously reported ortho-rhom-bic form [Yi & Hu (2009 ▶). Acta Cryst. E65, o2643], in which the complete mol-ecule is generated by a crystallographic twofold axis.
authors.affiliation: School of Applied Chemical Engineering, The Research Institute of Catalysis, Chonnam National University, Gwangju 500-757,  Republic of Korea.
authors.forename: Kwang
authors.initials: K
authors.lastname: Ha