title: Two-dimensional hydrogen-bonded networks in 1-(diaminomethylene)thiouron-1-ium nitrate and bis[1-(diaminomethylene)thiouron-1-ium] phosphonate monohydrate.
abstract: Crystals of the title compounds, C(2)H(7)N(4)S(+).NO(3)(-), (I), and 2C(2)H(7)N(4)S(+).HPO(3)(2-).H(2)O, (II), are built up from 1-(diaminomethylene)thiouron-1-ium cations and nitrate anions in (I), and from phosphonate anions and water molecules in (II). In both crystals, the cations and anions are linked together via N-H...O hydrogen bonds. The 1-(diaminomethylene)thiouron-1-ium cations exhibit a twisted conformation. Both arms of the cations are planar and are turned in opposite directions around the C-N bond involving the central N atom. Hydrogen-bonding interactions join oppositely charged units into layers in the nitrate salt and into double layers in the phosphonate monohydrate salt. In addition, the structures are stabilized by pi-pi interactions between the delocalized pi bonds of the cations. The significance of this study lies in the illustration of the differences between the supramolecular aggregations in the nitrate and phosphonate salts of a small organic molecule. The different geometries of the counter-ions and their different potential for hydrogen-bond formation results in markedly different hydrogen-bond arrangements.
authors.affiliation: Institute of Low Temperatures and Structures Research, Polish Academy of Sciences, PO Box 1410, 50-950 Wrocław, Poland. j.janczak@int.pan.wroc.pl
authors.forename: Jan
authors.initials: J
authors.lastname: Janczak
authors.forename: Genivaldo Julio
authors.initials: GJ
authors.lastname: Perpétuo