4-AMINO-6-METHOXY-2-METHYLTHIOPYRIMIDINE AND HG(II) SYSTEM - SOLUTIONAND 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 bee n studied by potentiometric methods at 25 degrees C and 0.1 M KCl ioni c strength. By fixing the appropriate pH conditions, solid species wit h 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 coor dinated by a terminal chloride ion, a HL molecule and two bridging chl oride ions. The Hg(II) ion is coordinated to HL via the N(3) endocycli c atom.