BY GORAN FALKENBERG
Department of Medical Physics, Karolinska Institutet, S-104 01 Stockholm, Sweden(Received 9 March 1972)
Department of Medical Physics, Karolinska Institutet, S-104 01 Stockholm, Sweden(Received 9 March 1972)
The hallucinogenic indole alkylamine, (N,N)-dimethyltryptamine, crystallizes in two modifications having the same monoclinic space group, P2/a and P21/c (Z= 8). For the latter, which has two molecules in the asymmetric unit, data were collected on an automatic diffractometer. Unit-cell dimensions area= 12.99, b= 12.08, c= 18.38/~, and fl= 127"85 °. The structure was determined by the symbolic addition procedure and refined by the method of full-matrix least squares to R = 0.048 for 2080 observed reflexions. The molecular structures of the two molecules are almost identical. The indole nuclei are planar, and the ethylamine side chain is almost fully extended (torsion angle z2= 176 and 188 ° for molecules A and B respectively) and lies near a plane which is approximately perpendicular to that of the indole(rl= 102 and 90°). Relatively strong N-H...N hydrogen bonds join A-molecules (2.92 A,) and B-molecules (2.89/%,) separately in two different helically fashioned hydrogen-bonding systems around screw axes.