(-)-Argemonine hemihydrate [systematic name: (6S,12S)-2,3,8,9-tetramethoxy-
13-methyl-13-azadibenzo[b,f]bicyclo[3.3.1]nona-2,6-diene hemihydrate], C21H
25NO4.0.5H(2)O, is a tertiary pavinane alkaloid. Both partially saturated n
itrogen heterocycles adopt twisted half-chair conformations. The angle betw
een the two aromatic rings is 86.90 (5)degrees.