COORDINATING PROPERTIES OF 2-ACETYLPYRIDINE THIOSEMICARBAZONE - PALLADIUM(II) COMPLEXES WITH NEUTRAL AND DEPROTONATED LIGAND - X-RAY STRUCTURE OF BROMO(2-ACETYLPYRIDINE THIOSEMICARBAZONATO) PALLADIUM(II)

The preparation of the complexes PdLX, [Pd(HL)2]X2 and PdL2 (X = Cl, B r; HL and L the neutral and deprotonated ligand) is described. The new complexes have been characterized by elemental analyses, conductivity measurements and spectroscopic (IR and UV-vis) studies and the crysta l and molecular structure of PdLBr has been determined by single-cryst al X-ray diffraction. The palladium atom has a square planar geometry with three donor atoms (NNS) coming from L to form a planar tricyclic ligating system, and one bromide atom. All data are discussed in terms of assigned structural type and the nature of the bonding. The proton ation constants of the ligand, Ka1 and Ka2, were determined by spectro photometry and the logarithms of their values were found to be equal t o 11.43 +/- 0.02 and 3.98 +/- 0.02.