Hydrogen bonds involving polar CH groups. Part 11. Further confirmation of intramolecular bonds to nitrogen in 2-aminoalkyl-1,3-dithiane 1,1,3,3-tetraoxides by X-ray crystal structure analysis

Abstract

Crystal structures have been determined for 2-(3-dimethylamino-2-methylpropyl)-1,3-dithiane 1,1,3,3-tetraoxide (1) and 2-(2-morpholinoethyl)-1,3-dithiane 1,1,3,3-tetraoxide (2), two compounds having C–H ⋯· N intramolecular hydrogen bonds in solution. Crystals of both are monoclinic, space group P2₁/n, and have unit cell dimensions, a= 19.144(4), b= 9.372(3), c= 16.561(5)Å, β= 108.74(2)°, Z= 8, and a= 9.534(1), b= 20.563(3), c= 6.936(1)Å, β= 99.81(1)°, Z= 4, respectively. Both structures were solved by direct methods, refinements being to R= 0.052 for 3 432 independent reflections in (1), and to R= 0.079 for 2 168 in (2). Two conformations of (1) exist per asymmetric unit, one having an intramolecular C–H ⋯· N hydrogen bond as confirmed by an N ⋯· H distance of 2.41 Å and appropriate geometry about nitrogen; the second is in an open conformation with an intermolecular C–H ⋯· O hydrogen bond (2.39 Å) to a sulphone oxygen of the other molecule. There is some disorder in the side chain. Compound (2) is highly disordered, but the conformation also suggests an intramolecular C–H ⋯· N hydrogen bond with an N ⋯· H distance of 2.57 Å.