A new coordination complex, aqua bis(o-phenanthroline) cadmium(II) sulfate cyanoguanidine pentahydrate, [Cd(o-phen) 2 (SO 4 )(H 2 O)](cnge) Á 5H 2 O, was synthesized and characterized. The crystal structure was solved by X-ray diffraction methods. It crystallizes in the monoclinic space group P2 1 /n with a ¼ 13.7650(2) A ˚, b ¼ 10.2796(2) A ˚, c ¼ 21.4418(3) A ˚, ¼ 90.106(2) , and Z ¼ 4 molecules per cell unit. The cadmium(II) is in a distorted octahedral environment coordinated to two nearly planar and mutually perpendicular o-phenanthrolines, one oxygen atom of sulfate, and a water molecule. Non-bonded and planar cyanoguanidine and five crystallization water molecules complete the asymmetric unit. Vibrational (FT-IR and FT-Raman) spectroscopies and thermogravimetric determinations support this structure. Intensity enhancement of the fluorescence spectrum may be a demonstration of the interaction of the metal with phenanthroline. In solution the coordination behavior is rather different, and the speciation studies point to coordination of both cnge and phenanthroline to cadmium. The improvement of the antibacterial activity of cadmium upon complexation has been determined.

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An octahedral Zn complex with o-phenanthroline (o-phen) and cyanoguanidine (cnge) has been synthesized and characterized. The crystal structural data show the formation of a ZnN 5 O core where the metal coordinates to two mutually perpendicular o-phenanthrolines as bidentate ligands [Zn-N bond lengths in the 2.124(2)-2.193(2) Å range], the cyanide nitrogen of a cnge [d(Zn-N) ¼ 2.092(2) Å , ff(Zn-N-C) ¼ 161.1(2) ], and a water molecule [d(ZnOw) ¼ 2.112(2) Å ]. Spectral data (FT-IR, Raman, and fluorescence) and speciation studies are in agreement with the structure found in the solid state and the one proposed to exist in the solution. To evaluate the changes in the microbiological activity of Zn, antibacterial studies were carried out by observing the changes in minimum inhibitory concentration of the complex, the ligands, and the metal against five different bacterial strains. The antibacterial activity of Zn improved upon complexation in three of the tested strains.