Synthesis and crystal structure of the salt of the protonated thiamine cation with the palladium(II) tetrachloride anion [HTA]₂[PdCl₄]Cl₂ · 2H₂O

Abstract

The reaction of thiamine chloride hydrochloride with a solution of palladium chloride in hydrochloric acid gave a protonated thiamine salt [HTA]₂[PdCl₄]Cl₂ · 2H₂O (I) (TA is 4-methyl-3-[(2′-methyl-4′-amino-3′,4′-dihydropyrimidinyl-5′)methyl]-5-(2-hydroxyethyl)thiazolium cation, C₁₂H₁₆N₃O₂S). The crystal structure of I was determined by X-ray diffraction. The crystals are triclinic: a = 11.459(8) Å, b = 12.239(8) Å, c = 6.910(1) Å, α = 103.24(3)°, β = 76.95(3)°, γ = 106.04(3)°, Z = 2, space group P $\bar 1$. The structural units of I are doubly charged [HTA]²⁺ cations, [PdCl₄]²⁻ and Cl⁻ anions, and crystallization water molecules combined by hydrogen bonds and electrostatic interactions. The planar thiazolium and pyrimidine rings are in the F conformation, Φ_t = 1.0°, Φ_p = −86.6°, and the dihedral angle between the planes is 85.5°. The torsion angles of the hydroxyethyl group are as follows: C(9)C(10)C(11)O(1), 175.6°; S(1)C(9)C(10)C(11), 33.2°; it is involved in the hydrogen bond with the free Cl⁻ anion. The sulfur atom forms a short (3.052 Å) intermolecular S-Cl contact with the chlorine atom of the [PdCl₄]²⁻ anion, which forms supramolecular chains.