http://www.arkat-usa.org/get-file/23558/

The structure of 2,3-dihydro-3-(2,4-dioxo-6-methylpyran-3-ylidene)-2-(2-nitrobenzyl)-1,4-benzothiazine and the problem of orthogonal interactions

The structure of the title compound has been determined. The compound crystallizes in the P21/n space group with 4 molecules in the unit cell.  The structure is consistent with previous conclusions based on NMR spectroscopy; moreover it provides new information about the conformation of the thiazine  ring, the nature of the intramolecular hydrogen bond and the sulfur/nitro "orthogonal interaction". This last aspect has been examined through the use of DFT calculations on a simplified model system.