CRYSTAL-STRUCTURES OF 2 N-SUBSTITUTED 2-THIOXO-1,3-DITHIOLE-4-CARBOXAMIDES

The two closely related compounds N,N-dimethyl 5-(methylthio)-2-thioxo -1,3-dithiole-4-carboxamide 1 and N-(p-methoxy-phenyl)-N-methyl 5-(met hylthio)-2-thioxo-1,3-dithiole-4-carboxamide 2 have been characterized by X-ray crystal structure determination, Crystal data for 1: triclin ic, P ($) over bar 1, a = 6.767(1), b = 12.594(2), c = 6.648(1) Angstr om, alpha = 101.38(1), beta = 93.37(2), gamma = 79.62(1)degrees, V = 5 46.2 Angstrom(3), Z = 2. Crystal data for 2: monoclinic, Cc, a = 19.83 6(4), b = 6.057(1), c = 15.860(3) Angstrom, beta 127.61(3)degrees, V = 1509.5 Angstrom(3), Z = 4. The molecular structures of 1 and 2 show r emarkable differences concerning the conformational behavior. These di fferences are related to the nature of the substituents at the nitroge n atom. The presence of an aromatic system in 2 leads to an almost pla nar arrangement of the alpha-oxoketene dithioacetal moiety. This effec t is accompanied by a short intramolecular S ... O contact of 2.648(2) Angstrom. In the absence of an aromatic system, as is the case for co mpound 1, neither a resonance effect along the alpha-oxoketene dithioa cetal fragment nor a short S ... O distance is observed.