3-Methyl-4,5,6,7,8,9-hexahydrocycloocteno-1,2,3-selenadiazolium iodide–trichloromethane (4/1)

Abstract

The title solvated salt, 4C 9 H 15 N 2 Se + Á4I À ÁCHCl 3 , co-crystallizes with chloroform. The asymmetric unit contains four very similar ion pairs and one solvent molecule. In the crystal, layers of parallel chloroform-filled channels formed by two different ion pairs alternate with layers formed by the other two ion pairs. Disorder is observed for some C and H atoms in two of the cations with occupancy ratios of 0.68:0.32 and 0.62:0.38. Structure description1,2,3-Selenadiazoles are useful precursors for strained cycloalkynes (Bissinger et al., 1988;Detert & Meier, 1997). Cycloocteno-1,2,3-selenadiazole, first prepared by Meier & Voigt (1972), reacts with iodomethane to yield the 3-methyl-substituted selenadiazolium iodide. Crystals with this cation have been obtained with a 2/1 mixture of iodide and triiodide anions (Schollmeyer & Detert, 2016). Here, the only anion is iodide, but the compound co-crystallizes with 1/4 chloroform molecules per ion pair. The molecular geometries of the cations reported here and in the previous article are nearly identical.The asymmetric unit (Fig. 1) is composed of four slightly different ion pairs of the title compound and one chloroform molecule. The cations A, B, and C are very similar, differing from cation D. All cations adopt an l-type shape, but the conformation at C6-C7 of the hexamethylene tether is inverted in D. All heterocyclic rings are identical, with a maximum deviation of 0.02 Å at N2(A) from the mean plane.In all ion pairs, the shortest distance between the iodide and the cation is to atom N2 of the selenadiazolium ring: N2AÁ Á ÁI2 = 3.869 (9) Å , N2B Á Á ÁI1= 3.287 (9) Å , N2CÁ Á ÁI3 = 3.754 (8) Å and N2DÁ Á ÁI4 = 3.768 (9) Å . Only N1C has a comparable distance to the next iodide: N1CÁ Á ÁI3 = 3.784 (9) Å . The shortest spacing between iodide ions are I1Á Á ÁI4 = 6.042 (1) Å and I4Á Á ÁI4 = 5.940 (2) Å .