Chemistry of torasemide. Molecular and crystal structure of new polymorph N

It is known from literature that torasemide, generic name for N-1 isopropyl -N-3-[4-(3-methylphenylamino)-3-pyridylsulphonyl]urea can have two polymorp hic forms, denoted as T-I and T-II. A novel, third polymorph N of torasemid e, T-N has been discovered and fully characterised. It crystallises in the centrosymmetric monoclinic space group P2(1)/c with two crystallographicall y independent molecules, which differ primarily in their different phenyl r ing and N-1-isopropyl side chain orientations. Both independent molecules, i.e. conformations, can adopt a zwitter-ionic structure. The new polymorph of torasemide is characterised by a considerably complex three-dimensional hydrogen-bonding network that spans all over the crystal unit cell. The cry stal packing of T-N is rather crowded, dense and compact. It is pointed out that the degree of crystal structure diversity of the existing torasemide polymorphs is considerably high, with different conformational properties o f distinct torasemide molecules in its asymmetric unit.