Interactions in molecular crystals, 146 - The crystal structure of N,N '-ditosyl-p-phenylenediamine, density functional theory calculations of conformations and hydrogen bond motifs in sulfonamides

In a study preceeding the investigation of a novel class of inclusion compo unds, the low-temperature crystal structure of the host-molecule N,N'-ditos yl p-phenylenediamine has been determined. It crystallizes in the monoclini c space group P2(1)/n with two formula units in the unit cell, forming laye rs of hydrogen-bonded molecules. The essential subunits are rigid phenyl ri ngs and flexible sulfonamide linkages C-N(H)-S(O-2)-C, the conformations of which are discussed by comparison with data from the Cambridge Structural Database and based on density functional theory (DFT) as well as semiempiri cal PM3 calculations for the selected model compounds. N-methyl-methane-, N -methyl-benzene- and N-phenyl-methane-sulfonamide. The torsion angle depend ent energy and enthalpy profiles allow estimates of the rotational barriers around the C-S-N-C bonds. In addition, potential hydrogen bonding by the h ost molecule is discussed in comparison to analogous carbonic acid derivati ves.