CHARACTERIZATION AND PROPERTIES OF MONOAMMINE NITROIMIDAZOLE COMPLEXES OF PLATINUM [PTCL2(NH3)(NO2IM)] - CRYSTAL AND MOLECULAR-STRUCTURE OF CIS-AMMINEDICHLORO(1-((((2-HYDROXYETHYL)AMINO)CARBONYL)METHYL)-2-NITROIMIDAZOLE)PLATINUM(II)

The characterization of monoammine(nitroimidazole)platinum(II) complexes of structure [PtCl2(NH3)(NO2Im)] (NO2Im = 1-{(((2-hydroxyethyl)amino)carbonyl)methyl}-2-nitroimidazole, Etanidazole (I), 1-{2-nitro-1-imidazolyl}-3-methoxy2-propanol, Misonidazole (II), and 1-{2-hydroxyethyl}-2-methyl-5-nitroimidazole, Metronidazole (III)) is reported. Both cis and trans isomers may be isolated for II and III. The crystal structure of cis-amminedichloro(1-{(((2-hydroxyethyl)amino)carbonyl)methyl}-2-nitroimidazole)platinum(II) has been determined by X-ray diffraction. The crystals are orthorhombic, space group Pnab with cell dimensions a = 14.867 (7) angstrom, b = 9.915 (5) angstrom, c = 19.015 (9) angstrom, and Z = 8. The structure was refined to R = 0.062 and R(w) = 0.052. Platinum has the expected square-planar coordination. The Pt-Cl bond trans to the nitroimidazole ligand is shorter (2.269 (3) angstrom) than normal. The dihedral angle between the platinum plane and the imidazole ring is 111-degrees, while the nitro group makes an angle of 31-degrees with the imidazole ring plane. Electrochemistry and Pt-195 NMR data are also reported. The relevance of the chemical properties to their biological properties as radiosensitizers and hypoxic cytotoxins is discussed.