THIAMIN THIOTHIAZOLONE ACETONE SOLVATE, C12H16N4OS2.0.5C3H6O

The structure of thiamin thiothiazolone {TTT; 5-(2-hydroxyethyl)-4-met hyl-2(3H)-thiazolethione}, originally known as a transition-state anal ogue of thiamin, is quite different from that of its congener thiamin thiazolone (TT). TTT assumes the S conformation [phi(T) = +/- 83 (1)-d egree; phi(P) = +/- 176 (1)-degree], while TT assumes the V conformati on [phi(T) = +/- 104 (1)-degree; phi(P) = +/- 74 (1)-degree] with an i ntramolecular N-H...O hydrogen bond. The conformations of the hydroxye thyl side chains are also different, so that TTT has a close delta+S.. .O(delta-) electrostatic interaction while TT does not. Crystal packin g consists of a three-dimensional hydrogen-bonding network formed by t hree unique hydrogen bonds. There are two kinds of hydrogen-bonded mol ecular dimer. The acetone molecule is statistically disordered in the cavity formed by the two centrosymmetrically related pyrimidine base p airs.