ZN(II) COMPLEXES WITH THIOPYRIMIDINE DERIVATIVES - SOLUTION STUDY, SYNTHESIS AND CRYSTAL-STRUCTURE OF A ZIGZAG CHAIN ZINC(II) COMPLEX WITH THE LIGAND 4,6-DIMETHYL-2-THIOPYRIMIDINE

The acid-base properties of the pyrimidine derivative 4,6-dimethyl-2-t hiopyrimidine (HL) have been determined. The protonation constants of anionic L and neutral HL and the stability constants of the Zn(II) com plexes formed with this ligand were determined by potentiometric measu rements at 25-degrees-C and 0.1 M KCl ionic strength. The molecular st ructure of the solid complex [ZnL2]n has been established by single-cr ystal X-ray diffraction. The crystals of the compound are orthorhombic , of space group P2(1)2(1)2(1), with cell constants a = 7.984(1), b = 13.476(2), c = 13.709(2) angstrom, Z = 4 and D(c) = 1.548 g cm-3. The structure was solved and refined to R = 0.055 (R(w) = 0.051) and consi sts of infinite zig-zag chains running along the a axis. The geometry of each ZnN3S2 chromophore is almost an ideal trigonal bipyramid.