W0067

Experimental Determination of the Charge Density of Mesulergine, A Dopamine Agonist. Cheryl L. Klein Stevens and Naijue, Zhu, Dept. of Chemistry, Xavier Univ. of Louisiana, New

Orleans, LA 70125 and Edwin D. Stevens, Dept. of Chemistry, Univ. of New Orleans, New Orleans, LA 70148.

Mesulergine is a dopamine agonist belonging to the ergoline class of compounds. Dopamine agonists are potentially useful in the treatment of Parkinson’s disease. A total of 52,508 reflections were measured on a Bruker SMART 1K CCD X-ray diffractometer at 120(2) K to a 2__max of 72.6_. Integration of these intensities resulted in 9,418 unique reflections with R_int = 0.0474. Unit cell dimensions were determined to be a = 12.1281(3) Å, b = 6.1357(2) Å, c = 13.5935(4) Å, _ = 105.6310(10)_ for space group P2₁. A conventional refinement of 26 non-hydrogen atoms and 27 hydrogen atoms resulted in R = 0.044. A fit of the data to a monopole model gave an R = 0.047 while a full multipole refinement gave R = 0.032. Preliminary deformation density maps that resulted from this study are excellent and clearly show a buildup of electron density in the electron rich areas of the molecule. A deformation density map of the sulfone shows a buildup of electron density in the S=O bonds with some deformation density associated with the oxygen lone pairs. Preliminary molecular electrostatic potential maps have been calculated and show a region of negative potential associated with a region of reactivity near a nitrogen atom.

(Support from the NIH/MBRS-SCORE grant is gratefully acknowledged S06 GM08008.)