Interactions of thiamine monophosphate (TMP) with one- and two-dimensional polymeric halogenomercurate anions. Crystal structures of (TMP)(Hg 2Br 5)·0.5H 2O and (TMP) 2(Hg 3I 8)

Abstract

An investigation into the interactions between thiamine monophosphate (TMP) and anions has resulted in the preparation and X-ray characterization of the compounds (TMP)(Hg 2Br 5)·0.5H 2O ( 1) and (TMP) 2(Hg 3I 8) ( 2). In each compound the TMP molecule exists as a monovalent cation in the usual F conformation. The halogenomercurate anions occur in two-dimensional (2-D) network in 1 or one-dimensional (1-D) chain in 2. In both 1 and 2, the structures consist of alternating cationic sheets of the hydrogen-bonded TMP molecules and anionic sheets of the polymeric halogenomercurate anions. The TMP molecule binds to the polymeric anions through the characteristic ‘anion bridge I’, C(2)H⋯X⋯pyrimidinium (X=Br in 1 and I in 2), and electrostatic interactions between electropositive S(1) and halogen atoms. The ‘anion bridge II’ of the type N(4′1)H⋯X⋯thiazolium (X=phosphate group) plays a role in stabilizing the molecular conformation. The biological implication of the host–guest-like complexation between TMP and polymeric anions is discussed.