Supramolecular association in proton-transfer adducts containing benzamidinium cations. I. Four molecular salts with uracil derivatives.

摘要: Four organic salts, namely benzamidinidium orotate (2,6-dioxo-1,2,3,6-tetrahydropyrimidine-4-carboxylate) hemihydrate, C(7)H(9)N(2)(+).C(5)H(3)N(2)O(4)(-).0.5H(2)O (BenzamH(+).Or(-)), (I), benzamidinium isoorotate (2,4-dioxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate) trihydrate, C(7)H(9)N(2)(+).C(5)H(3)N(2)O(4)(-).3H(2)O (BenzamH(+).Isor(-)), (II), diliturate (5-nitro-2,6-dioxo-1,2,3,6-tetrahydropyrimidin-4-olate) dihydrate, C(7)H(9)N(2)(+).C(4)H(2)N(3)O(5)(-).2H(2)O (BenzamH(+).Dil(-)), (III), and 5-nitrouracilate (5-nitro-2,4-dioxo-1,2,3,4-tetrahydropyrimidin-1-ide), C(7)H(9)N(2)(+).C(4)H(2)N(3)O(4)(-) (BenzamH(+).Nit(-)), (IV), have been synthesized by a reaction between benzamidine (benzenecarboximidamide or Benzam) the appropriate carboxylic acid. Proton transfer occurs to imino N atom. In all four acid-base adducts, asymmetric unit consists of one tautomeric aminooxo anion (Or(-), Isor(-), Dil(-) Nit(-)) monoprotonated cation (BenzamH(+)), plus one-half (which lies across twofold axis), three two solvent water molecules in (II) respectively. Due presence protonated benzamidine, these complexes form supramolecular synthons characterized N(+)-H...O(-) N(+)-H...N(-) (+/-)-charge-assisted hydrogen bonds (CAHB).