Reactivity of fluoro-substituted bis(thiocarbonyl) donors with diiodine: an XRD, FT-Raman, and DFT investigation.

The reactions of 1,3,8,10-tetrakis(4'-fluorophenyl)-4,5,6,7-tetrathiocino[1,2-b:3,4-b']diimidazolyl-2,9-dithione (4) and molecular diiodine afforded spoke adducts with stoichiometries 4·I2 and 4·3I2 , isolated in the compound 4·3I2·xCH2Cl2·(1-x)I2 (x=0.70), and characterized by single-crystal XRD and FT-Raman spectroscopy. The nature of the reaction products was investigated under the prism of theoretical calculations carried out at the DFT level. The structural data, FT-Raman spectroscopy, and quantum mechanical calculations agree in indicating that the introduction of fluorophenyl substituents results in a lowering of the Lewis basicity of this class of bis(thiocarbonyl) donors compared with alkyl-substituted tetrathiocino donors and fluorine allows for extended interactions that are responsible for solid-state crystal packing.

Delta-sulfanilamide.

The delta polymorph of sulfanilamide (or 4-aminobenzenesulfonamide), C(6)H(8)N(2)O(2)S, displays an overall three-dimensional hydrogen-bonded network that is dominated by a two-dimensional substructure with R(2)(2)(8) rings; these result from dimeric N-H...O interactions between adjacent sulfonamide groups. This study shows how the polymorphism of sulfanilamide is linked to its versatile hydrogen-bonding capabilities.

Polymorph VI of sulfapyridine: interpenetrating two- and three-dimensional hydrogen-bonded nets formed from two tautomeric forms.

Polymorph VI of 4-amino-N-(2-pyridyl)benzenesulfonamide, C(11)H(11)N(3)O(2)S, is monoclinic (space group P2(1)/n). The asymmetric unit contains two different tautomeric forms. The structure displays N-H...N and N-H...O hydrogen bonding. The two independent molecules form two separate two- and three-dimensional hydrogen-bonded networks which interpenetrate. The observed patterns of hydrogen bonding are analogous to those in polymorph I of sulfathiazole.