CIS-5-HYDROPEROXY-6-HYDROXY-5,6-DIHYDROTHYMINE - CRYSTAL-STRUCTURE AND THEORETICAL INVESTIGATIONS OF THE ELECTRONIC-PROPERTIES BY DFT

The structure of cis-5-hydroperoxy-6-hydroxy-5,6-dihydrothymine was ob tained using X-ray crystallography [space group P2(1)/n (Z = 4) with a = 11.428(2) Angstrom, b = 6.284(1) Angstrom, c = 11.882(2) Angstrom a nd beta = 110.56(3)degrees]. Electronic properties of the thymine hydr oxyhydroperoxide were determined, both in the solid state form and in the free molecule form, using LSD-DFT theory calculations. Only slight differences between the crystal structure and the optimized geometry are observed. On the other hand, the two structures exhibit significan t differences in their electronic properties. In particular? the dipol e moment of the crystal structure is larger than that of the theoretic al geometry. This is probably due to the occurrence of hydrogen bonds in the crystal, A large hydrogen bond network, as well as unusual coul ombic interactions between the different molecules in the crystal, are responsible for the molecular packing. These observations lead to a b etter understanding of the structural changes that occur during the hy droxyl radical-mediated decomposition of thymine, (C) 1998 Elsevier Sc ience B.V.