Interactions of thiamine with anions: (Hthiamine)(thiamine) heptaiododimercurate dihydrate and its dimethanol monohydrate

In the title compounds, 3-[(4-amino-2-methyl-5-pyrimidinio)methyl] -5-(2-hydroxyethyl)-4-methylthiazolium(2+) 3-[(4-amino-2-mcthyl-5-pyrimidinyl)methyl]-5-(2-hydroxyethyl)-4-methylthiazolium( 1+) heptaiododimercurate dihydrate, (C12H18N4OS)(C12H17N4OS)[Hg2I7]. 2H(2)O, (I), and its dimethanol monohydrate, (C12H18N4OS)(C12H17N4OS)[Hg2I7]. 2CH(3)OH . H2O (2), a crystallographic centre of symmetry in (1) or a twofold axis in (2) is imposed between the protonated and deprotonated thiamine molecules, resulting in a statistically half-occupied proton attached at N1' of the pyrimidine ring. The Hg2I73- anion, residing on the centre of symmetry in (1) or on the twofold axis in (2), interacts with two thiamine molecules, each through a C2-H ... I ... pyrimidine-ring interaction. This bridging interaction is a characteristic of thiamine in the F conformation.