16561-17-4Relevant academic research and scientific papers
Structure and Electrochemical Properties of the New Triply Bridged Molybdenum(V) Complex 2
Cervilla, Antonio,Llopis, Elisa,Ramirez, Jose A.,Domenech, Antonio,Palanca, Pedro,et al.
, p. 175 - 184 (1994)
The reaction of molybdate ions with an excess of thioglycolic acid has been studied in aqueous solution at room temperature by UV/VIS and NMR spectroscopy.As previously observed, spectroscopic data suggest initial formation of the complex (2-) 1, which is subsequently reduced by the excess of acid.Two molybdenum(V) complexes are formed in equilibrium in this redox reaction.The main product has been isolated as an orange-red solid with the formula 2*2H2O 2.It crystallizes in the monoclinic space group P21/a with a = 20.761(8), b = 17.441(7), c = 14.587(6) Angstroem, β = 101.08(6) deg, and Z = 4.The structure contains two cofacial Mo(V)O2(SCH2CO2)2 distorted octahedra sharing one oxygen atom and one thioglycolate ligand on a pseudo-symmetry plane (Ot-Mo 1.677, Mo-Mo 2.643, Mo-St,b 2.489, Mo-Ot,b 2.337, Mo-Ob 1.929 Angstroem, Mo-St,b-Mo 64.1, Mo-Ot,b-Mo 68.9, Mo-Ob-Mo 86.5 deg; t = terminal, b = bridging).Cyclic voltammetry shows that complexes 1 and 2 undergo a two-electron irreversible reduction at -1.27 and -1.38 V vs. the saturated calomel electrode, respectively, in methanol.In both reduction processes the monooxomolybdenum(IV) species (2-) and are generated.A reaction mechanism for the oxidation of thioglycolic acid by molybdate ions is proposed from the combined analysis of spectrophotometric, NMR, structural, and voltammetric data.Dimeric molybdenum(V) products are generated from reaction of the above monooxomolybdenum(IV) species with the starting dioxomolybdenum(VI) complex 1.A particularly remarkable supporting feature is the formation of Me2S when the reaction is carried out in the presence of Me2SO.
Nuclear magnetic resonance studies of the solution chemistry of metal complexes. 20. Ligand-exchange kinetics of methylmercury(II)-thiol complexes
Rabenstein, Dallas L.,Reid, R. Stephen
, p. 1246 - 1250 (2008/10/08)
The kinetics of the exchange of methylmercury, CH3HgII, between thiol ligands in aqueous solution was studied by 1H NMR spectroscopy over a range of pH values. Exchange of CH3HgII between two different mercaptoacetic acid ligands and between mercaptoacetic acid and cysteine, penicillamine, or glutathione was found to be by displacement of complexed thiol by free thiol at pH >1. The exchange rate is pH dependent due to the effect of protonation of the ligand. For the amino acid and peptide ligands, exchange at physiological pH is predominantly via displacement of complexed mercaptoacetic acid by the amino-protonated, thiol-deprotonated form of the displacing ligand. At pH 3HgII with free thiol. The second-order rate constants for displacement of complexed thiol by free thiol are consistent with an associative mechanism, in which the exchange rate constant is determined by the free energy difference between the two complexes.
