Crystal structure of the supramolecular system of indole-2,3-dione 1-(2-oxopropyl)-3-ethylene ketal and its thiosemicarbazone

Abstract

The crystal structure of a supramolecular system consisting of indole-2,3-dione 1-(2-oxopropyl)-3-ethylene ketal (I) and indole-2,3-dione 1-(2-oxopropyl)-3-ethylene ketal thiosemicarbazone (II) molecules that are linked together by hydrogen bonds is determined using X-ray diffraction. The crystal is monoclinic, and the unit cell parameters are as follows: a = 12.8360(3) A, b = 10.7330(3) A, c = 19.4610(3) A, β = 99.566(1)°, space group P21/c, and Z = 4 (C27H29N5O7S). In molecules I and II, the indole-2,3-dione 3-ethylene ketal fragments have a virtually identical structure. The pyrrole and dioxolane fragments are spiro-linked through the carbon atom with a dihedral angle close to 90°. The adjacent pyrrole and benzene rings are coplanar to within 4.4°. In molecule II, the oxygen atom of the dioxolane fragment and the terminal nitrogen atom of the thiosemicarbazide fragment are involved in the N-HiO intramolecular hydrogen bond [3.294(2) A]. The key role in the formation of the crystal structure is played by intermolecular hydrogen bonds of the N-H⋯dO, C-H⋯O, C-H⋯N, and N-H⋯S types.