[1,4]Ditellurino[2,3-b:5,6-b′]dipyrazine

Abstract

[1,4]Ditellurino[2,3-b:5,6-b′]dipyrazine represents the first reported [1,4]chalcogena[2,3-b:5,6-b′]dipyrazine containing a heavy chalcogens The asymmetric unit consists of three molecules. In contrast to its sulfur analog, which is planar [Lynch et al. (1994) Cryst. Struct. Commun. 50,1470–1472], C8H4N4Te2 is folded along the Te...Te axis to accommodate the larger chalcogenide atoms. The dihedral angle between the two Te2C2 rings of the central ring is 57.9° (mean of three). C—Te bond lengths range from 2.1105 (16) Å to 2.1381 (17) Å, in good agreement with those predicted by their covalent radii. All Te atoms are involved in intermolecular Te...N contacts, with distances in the range 2.894 (2) to 2.963 (2) Å. These result in a spiral supramolecular assembly, forming helical columns.