Crystal structures of the Teonanácatl hallucinogens. Part I. Psilocybin C12 H17 N2 O4 P

The crystal structure of psilocybin, the major hallucinogenic component of Teonanácatl, the sacred mushroom of Mexico, has been determined in crystals of the monomethanolate. Crystals are monoclinic, space group P21/c, a= 1264(1), b= 2911(2), c= 884·7(6) pm, β= 107·37(2)°, and contain two molecules of psilocybin and two molecules of methanol of solvation per asymmetric unit. Data were collected on a four-circle diffractometer; the structure was solved by direct methods and refined by block-diagonal least squares to R0·049 over 4217 significant reflections. The two independent molecules are both zwitterions, have different conformations, and are involved in a complex hydrogen-bonding scheme in which there are very short phosphate-phosphate hydrogen bonds, and in which the methanol of solution also takes part. Significant deviations of the substituents from the indole plane are apparent. Bond lengths have been determined to a precision of 0·5 pm.