title: Vitamin C interaction with cobalt-ammine cations. Synthesis, spectroscopic and structural characterization of cobalt-pentammine and cobalt-tetrammine sugar complexes containing L-ascorbate anion.
abstract: Interaction between [Co(NH3)5Cl]Cl2, [Co(NH3)4Cl2]Cl and L-ascorbic acid has been investigated in aqueous solution and solid complexes of the type [Co(NH3)5 ascorbate]Cl2 X H2O and [Co(NH3)4 ascorbate]Cl2 X H2O have been isolated and characterized by 13C-NMR, FT-IR and electron absorption spectroscopy. Spectroscopic and other evidence suggested that the sugar anion binds monodentately in the [Co(NH3)5 ascorbate]2+ cation via the ionized O3 oxygen atom and bidentately in [Co(NH3)4 ascorbate]2+ through the O1 and O4 oxygen atoms, resulting in a six-coordinate geometry around the Co(III) ion. The intermolecular sugar hydrogen-bonding network is perturbed upon sugar metalation and the sugar moiety shows a similar conformation to that of the sodium ascorbate compound in these series of cobalt-ammine complexes.
mesh_terms: D001205:Ascorbic Acid / Q000031:analogs & derivatives* / Q000138:chemical synthesis; D002236:Carbohydrate Conformation; D003035:Cobalt; D005583:Fourier Analysis; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000138:chemical synthesis*; D013055:Spectrophotometry, Infrared
chemical_list: D009942:Organometallic Compounds; C051856:cobalt-tetrammine-ascorbate complex; C051857:cobalt-pentammine-ascorbate complex; D003035:Cobalt; D001205:Ascorbic Acid