X-RAY-INVESTIGATION OF GLYOXIME DERIVATIVES .5. 2 ISOMERS OF 2(THIENYL)GLYOXIME - A DATABASE STUDY OF THE GEOMETRY AND HYDROGEN-BONDING OF THE OXIME GROUP

The crystal structures of two isomers of 2-(thienyl)glyoxime, 2-thienylethanedial dioxime, C6H6N2O2S, E,E [orthorhombic, Pbca, a = 11.074(5), b = 9.152 (3), c = 14.660 (4) Angstrom, V = 1185.84 Angstrom(3), D-x = 1.522 g cm(-3), Z = 8, R = 0.058 for 1276 reflections with I > 3 sigma(I)] and E,Z [monoclinic, P2/c, a = 12.189 (3), b = 3.865 (3), c = 16.022 (5) Angstrom, beta = 90.79 (2)degrees, V = 754.8 Angstrom(3), D-x = 1.498 g cm(-3), Z = 4, R = 0.032 for 1154 reflections with I > 3 sigma(I)] have been determined. An analysis, based on the structures of the title compounds and on other glyoxime derivatives showed that the E,E-configuration is the preferred form. A statistical study on the geometry of the oxime group and on hydrogen bonding in the oximes was performed using the Cambridge Structural Database.