cis-PtCl(hp)(PPh3)2.py.EtOH (I; Hhp = 2-hydroxypyridine) and cis-Pt(hp)2(PPh3)2.2H2O (II) were prepared Their crystal structures have been determine by x-ray diffraction. In the two complexes the Pt(II) ion has an irregular square-planar stereochem. and the hp ligands coordinate to the Pt(II) through N in the pyridonate form. Crystal data for I: triclinic, space group P1, Z = 2, R = 0.051, Rw = 0.053; II, monoclinic, space group P21/n, Z = 4, R = 0.049, Rw = 0.058.

Key words: CRYSTAL STRUCTURE DETERMINATION, PYRIDINE P, PLATINUM COMPLEX, TRIPHENYLPHOSPHINE, ANION, TAUTOMERISM, COORDINATE CHEMISTRY, COORDINATION, HYDROXYL COMPOUNDS