Spectroscopic Studies and DFT Calculations of Cimetidine Complexes with Transition Metal Ions

The coordination behavior of the antiulcer drug cimetidine (cime) towards transition metal ions was investigated. The synthesis and characterization of [Cr(cime)(2)Cl-2]Cl center dot 3H(2)O, [Co(cime)Cl-2]center dot 5H(2)O, [Co(cime)(3)Cl]Cl center dot 3H(2)O, [Ni(cime)Cl2(H2O)(2)]center dot H2O, [Cu(cime) Cl-2]center dot 2H(2) O, [Cu(cime) 2Cl(H2O)]Cl center dot H2O, [Cu(cime)(3)Cl-2]center dot 3H(2)O, [Cu-2(cime) Cl-4], and [Zn(cime)Cl-2]center dot 1.5H(2)O are discussed, where cime acts as monodentate (imidazole N3) or bidentate ligand (N3 and S8). IR, UV-vis, EPR and NMR spectroscopies, mass spectrometry (FAB+), were employed for the characterization. In order to identify the most reactive areas of cimetidine, the electrostatic potential map of the ligand was calculated; also the structures of minimum energy of the coordination compounds were modeled using DFT (B3LYP/def2-TZVP) calculations.