4-Amino-6-methoxy-2-methylthiopyrimidine and Hg(II) system: Solution and solid state studies on metalated and N-coordinated species. Crystal structure of [Hg-2(HL)(2)(mu-Cl)(2)Cl-2]

The acid-base behaviour of the pyrimidine analogue 4-amino-6-methoxy-2-methylthiopyrimidine (HL) and the reactivity with Hg(II) ion have been studied by potentiometric methods at 25 degrees C and 0.1 M KCl ionic strength. By fixing the appropriate pH conditions, solid species with stoichiometries HgLCl . H2O and Hg-2(HL)(2)Cl-4 have been isolated. The spectroscopic study of the solids shows that HgLCl . H2O is a C(5)-organomercurial species, whereas the structure of Hg-2(HL)(2)Cl-4 has been determined by single crystal X-ray diffraction methods. Hg-2(HL)(2)Cl-4 is a binuclear complex with two Hg(II) ions tetrahedrally coordinated by a terminal chloride ion, a HL molecule and two bridging chloride ions. The Hg(II) ion is coordinated to HL via the N(3) endocyclic atom.