The stereochemical basis of anticonvulsant drug action. I. The crystal and molecular structure of diphenylhydantoin, a noncentrosymmetric structure solved by centric symbolic addition

Abstract

To investigate relationships between the molecular shape and biological activity of anticonvulsant drugs we have determined the molecular structure of diphenylhydantoin. The compound crystallizes in the orthorhombic system with cell dimensions a=6.230, b=13.581, c=15.532A,, space group Pn2~a. A total of 1210 independent reflections to 20= 50 ° for Mo K~ radiation was measured on a fourcircle diffractometer. The structure was solved by centrosymmetric phasing techniques, utilizing Sayre's equation for direct sign determination in space group Pnma. This technique proved successful because the 7-atom hydantoin group lies in a plane only 2.40 ° from (010) with the two phenyl rings on each side of the plane. Thus, the structure approximates the situation that would exist for special position (e) of Pnma, and many reflections have phases close to 0 or 7r. The plane of the hydantoin ring forms angles of 113 and 114 ° with the planes through the two phenyl rings. The phenyl-phenyl angle is 90 °. Final R index is 0-052.