title: A study on the nickel II-famotidine complexes.
abstract: Potentiometric studies have shown that Ni(II) forms three pH-dependent complexes with famotidine (L), namely: [NiHL](3+), [NiL](2+) and [NiH(-2)L]. Two of them have been isolated from solution with a Ni/famotidine ratio of 1:1. At pH 6.0, a paramagnetic complex [NiL](2+) with octahedral geometry is formed in which, most likely thiazole N(9) and guanidine N(3) nitrogens are involved in the metal binding. Additionally, two water molecules and two perchlorate anions, ClO(4)(-), fulfil the coordination sphere. The second complex, [NiH(-2)L], that precipitates at pH 8 is diamagnetic and takes square-planar geometry in which four nitrogen donors: N(3), N(9), N(16) and N(20) coordinate to Ni(II). Potentiometric studies, mass spectrometry, FT-IR and Raman spectroscopy are employed to determine and discuss the structure of both complexes. Additionally, 1H, 13C and 15N NMR spectroscopy is used to confirm the binding site in a square-planar complex. The assignment of vibrational bands are made using ab initio HF/CEP-31G method.
authors.affiliation: Faculty of Chemistry, Jagiellonian University, 3 Ingardena Str., 30-060 Cracow, Poland.
authors.forename: Malgorzata
authors.initials: M
authors.lastname: Barańska
authors.forename: Elzbieta
authors.initials: E
authors.lastname: Gumienna-Kontecka
authors.forename: Henryk
authors.initials: H
authors.lastname: Kozlowski
authors.forename: Leonard M
authors.initials: LM
authors.lastname: Proniewicz
mesh_terms: D015738:Famotidine / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D013058:Mass Spectrometry; D009532:Nickel / Q000737:chemistry*; D019906:Nuclear Magnetic Resonance, Biomolecular; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D011199:Potentiometry; D017550:Spectroscopy, Fourier Transform Infrared; D013059:Spectrum Analysis, Raman
chemical_list: D009942:Organometallic Compounds; D015738:Famotidine; D009532:Nickel