Metal-catalysed oxidation processes in thiosemicarbazones: new complexes with the ligand N-{2-([4-N-ethylthiosemicarbazone]methyl)phenyl}-p-toluenesulfonamide.
The coordination behaviour of a new thiosemicarbazone Schiff-base building block, N-{2-([4-N-ethylthiosemicarbazone]methyl)phenyl}-p-toluenesulfonamide, H2L1 (1), incorporating a bulky tosyl group, towards Mn II, Fe II, Co II, Ni II, Cu II, Zn II, Cd II, Ag I, Sn II, and Pb II has been investigated by means of an electrochemical preparative procedure. Most metal complexes of L1 have the general formula [M(L1)]2.nX (M=Mn, Fe, Co, Ni, Cu, Cd, Pb; n=0-4, X=H2O or CH3CN), as confirmed by the structure of [Pb(L1)]2 (15), in which the lone pair on lead is stereochemically active. This lead(II) complex shows an intense fluorescence emission with a quantum yield of 0.13. In the case of silver, the complex formed was found to possess a stoichiometry of [Ag2(L1)]2.3H2O. During reactions with manganese and copper metals, interesting catalysed processes have been found to take place, with remarkable consequences regarding the ligand skeleton structure. In synthesising the manganese complex, we obtained an unexpected dithiolate thiosemicarbazone tosyl ligand, H2L2, as a side-product, which has been fully characterised, including by X-ray diffraction analysis. In the case of copper, the solid complex has the formula [CuL1]2, but the crystallised product shows the copper atoms coordinated to a new cyclised thiosemicarbazone ligand, H2L3, as in the structures of the complexes [Cu(L3)]2.CH3CN (8) and [Cu(L3)(H2O)]2.CH3CN.H2O (9). The zinc complex [Zn(L1)]4 (12) displays a particular tetranuclear zeolite-type structure capable of hosting small molecules or ions, presumably through hydrogen bonding.
Pedrido
Rosa
R
Departamento de Química Inorgánica, Facultade de Química, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Spain.
Romero
María J
MJ
Bermejo
Manuel R
MR
González-Noya
Ana M
AM
García-Lema
Iria
I
Zaragoza
Guillermo
G
D002384:Catalysis; D018360:Crystallography, X-Ray; D004563:Electrochemistry; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D013058:Mass Spectrometry / Q000379:methods; D019216:Metals, Heavy / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D010084:Oxidation-Reduction; D013050:Spectrometry, Fluorescence / Q000379:methods; D013055:Spectrophotometry, Infrared / Q000379:methods; D013056:Spectrophotometry, Ultraviolet / Q000379:methods; D013449:Sulfonamides / Q000138:chemical synthesis / Q000737:chemistry*; D013882:Thiosemicarbazones / Q000737:chemistry*; D014050:Toluene / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry
D008024:Ligands; D019216:Metals, Heavy; C527509:N-(2-((4-N-ethylthiosemicarbazone)methyl)phenyl)-p-toluenesulfonamide; D009942:Organometallic Compounds; D013449:Sulfonamides; D013882:Thiosemicarbazones; D014050:Toluene