Crystal structures of the 2:2 complex of 1,1′-(1,2-phenylene)bis(3-m-tolylurea) and tetrabutylammonium chloride or bromide

Abstract

The title compounds, tetrabutylammonium chloride–1,1′-(1,2-phenylene)bis(3-m-tolylurea) (1/1), C16H36N+·Cl−·C22H22N4O2 or [(n-Bu4N+·Cl−)(C22H22N4O2)] (I) and tetrabutylammonium bromide–1,1′-(1,2-phenylene)bis(3-m-tolylurea) (1/1), C16H36N+·Br−·C22H22N4O2 or [(n-Bu4N+·Br−)(C22H22N4O2)] (II), both comprise a tetrabutylammonium cation, a halide anion and an ortho-phenylene bis-urea molecule. Each halide ion shows four N—H...X (X = Cl or Br) interactions with two urea receptor sites of different bis-urea moieties. A crystallographic inversion centre leads to the formation of a 2:2 arrangement of two halide anions and two bis-urea molecules. In the crystals, the dihedral angle between the two urea groups of the bis-urea molecule in (I) [defined by the four N atoms, 165.4 (2)°] is slightly smaller than that in (II) [167.4 (2)°], which is probably due to the smaller ionic radius of chloride compared to bromide.

Keywords

• crystal structure
• phenylene bis-urea
• tetrabutylammonium chloride
• tetrabutylammonium bromide
• anion binding