X-Ray Structure and Molecular-Packing Analysis of Artemetin

Abstract

5-Hydroxy-3,3' ,4',6,7-pentamethoxyflavone (flavone is 2-phenyl-4H-1-benzopyran-4-one ), C20H20- 08, M,= 388·4, monoclinic, P2/n, a= 7·518 (4), b=13·625(3), C=17·766(5)Á, P=98·52(3) 0 , V = 1803 (l)Á\ Z=4, Dx= 1·430Mgm-J, A.(MoKa) = 0·7107 A, !J = 0·104 mm-I, F(OOO) = 816, room temperature, final wR = 0·063 for 1480 observed reflexions. The benzopyran ring and the attached phenyl ring are quasi-planar. Dihedral angles between least-squares planes through each of the two rings are lower than 2°. An intramolecular 0-H ···O hydrogen bond exists involving hydroxyl and carbonyl groups of the phenyl and pyrone rings. Molecular-packing analysis in the atom-atom approach yields an equilib­ rium configuration in very good agreement with the experimental one.