Showing papers by "Carlo Preti published in 1980"

Osmium Carbodithioato Derivatives synthesis and spectroscopic studies

Abstract: Several new dithiocarbamate complexes of osmium(III) and osmium(II) have been synthetized and characterized by i. r. and electronic spectra, magnetic susceptibilities and conductivity measurements. The dithio ligands show a bidentate behaviour in all the complexes. From the electronic absorption spectra the values of the ligand field parameters were determined; the nephelauxetic parameter is indicative of a strong covalency in the metal-ligand bond as confirmed by the Dq values. All the complexes of osmium (III) and osmium(II) were octahedral, distorted owing to the presence of two molecules of coordinated water the metal(II) derivatives; the room temperature magnetic susceptibility values show that the complexes are of low-spin type: the osmium(III) derivatives have one unpaired electron, while the osmium (II) ones were diamagnetic. Osmium-Carbodithioato-Derivate. Darstellung und spektroskopische Untersuchungen Mehrere neue Dithiocarbamatkomplexe des OsIII und OsII werden dargestellt und durch IR- und UV-VIS-Spektren, magnetische Suszeptibilitaten und Leitfahigkeitsmessungen charakterisiert. Die Dithioliganden zeigen ein zweizahniges Verhalten in allen Komplexen. Aus den Elektronenspektren wurden die Ligandenfeldparameter bestimmt; der nephelauxetische Parameter deutet auf eine starke Kovalenz der Metall-Ligand-Bindung, was durch die Dq-Werte bestatigt wird. Alle Komplexe des OsIII und OsII sind oktaedrisch, bei den Metall(II)-Derivaten ver-zerrt infolge von zwei Molekulen koordiniertem Wasser. Die Werte der magnetischen Suszeptibilitaten bei Raumtemperatur zeigen, das die Komplexe vom Low-spin-Typ sind: Die Osmium(III)-Derivate haben ein ungepaartes Elektron, wahrend die Osmium(II)-Komplexe diamagnetisch sind.

The reactivity of areneseleninato complexes. new zinc(ii) benzeneseleninato derivatives with 1,10-phenanthroline as bidentate nitrogen donor ligand

Abstract: Treatment of the O,O′-seleninatodiaquozinc(II) derivatives of the type [Zn(H2 O)2 (X[sbnd]C6 H4 SeO2)2] (X=H, p-Cl, m-Cl, p-Br, m-Br, p-Me, p-NO2) with 1,10-phenanthroline produces 1 : 2 or 1 : 3 complexes, depending on the metal: o-phen stoichiometrical ratio. The 1 : 2 complexes were non-conducting and of the O-seleninato type, whereas the triscomplexes behaved as 1 : 2 electrolytes; the nitrogen donor ligand is always bidentate. The newly prepared complexes are characterized by far-I.R. and near-I.R. spectroscopy, as well as conductivity measurements. The possible stereochemistries of the complexes are discussed.

Cycloserine derivatives as ligands. cobalt(ii), nickel(ii), copper(ii), zinc(ii) and cadmium(ii) halide complexes of n 4,n′ 4-tereftal-bis(cycloserine)

Abstract: Transition metal(II) complexes of the cycloserine derivative, N 4,N′ 4-tereftalbis(cycloserine) or Terizidone, were prepared and investigated by means of magnetic measurements, electronic and infrared spectroscopy and conductivity measurements. The magnetic moments and electronic spectra of the Co(II) compounds are consistent with pseudotetrahedral and pseudooctahedral symmetries, whereas the Ni(II) complexes had a pseudotetrahedral geometry. The various ligand field parameters Dq, B′ and β have been evaluated; the B′ values suggest a strong covalency in the metal-ligand σ bond and the Dq values show a medium-strong ligand field. The position and multiplicity of the metal-halide stretching frequencies are discussed and used as a guide to the stereochemistry. Tetrahedral and octahedral structures are present in the zinc(II) and cadmium(II) complexes. The ligand was monodentate O-bonded or bidentate O,O′-bonded through the oxygen of the keto groups. We have never observed a metal-induced cycloserin...

Synthesis and characterization ofpara- andmeta-substituted benzeneseleninato complexes of tin(II), silver(I) and iron(II)

Abstract: New complexes of tin(II), silver([) and iron(II) withpara- andmeta-substituted benzeneseleninic acids are reported and studied by chemical analyses, spectroscopic methods, conductivity and magnetic measurements. The complexes, of the type Sn(XC6H4SeO2)2, Ag(XC6H4SeO2) and Fe(H2O)2(XC6H4SeO2)2, were obtained by reaction of SnCl2, · 2 H2O. AgNO3 and Fe(NH4)2(SO4)2·6 H2O with the sodium benzeneseleninates, XC6H4SeO2Na (X = H.p-Cl,m-Cl,p-Br,m-Br orp-Me). The i.r. spectral data suggest that the silver and iron complexes contain RSeO 2 − ligands which act as bidentates in O,O′-seleninato complexes. All the iron complexes have a distorted octahedralD 4h symmetry. The number of bands in the i.r. spectra of the tin derivatives indicates that there is no equivalence in the manner in which the two seleninato ligands are bonded. We could suggest that the tin atoms are intermolecularly O.O′-bonded via one RSeO 2 − group, whereas the second ligand is coordinated to the metal via one oxygen atom forming polymeric Ψ-tetrahedral derivatives.

Metal-ligand bonding in benzeneseleninato complexes of p- and d- block metals

Abstract: New complexes of lead(II) and zirconium(IV) withmeta-andpara-substituted benzeneseleninic acids are reported and characterized by chemical analyses, spectroscopic methods and conductivity and magnetic measurements The complexes are of the Pb(XC6H4SeO2)2 and ZrO(XC6H4SeO2)2 type; for zirconium(IV), working with a 1:4 metal:ligand stoichiometrical ratio, invariably the oxy derivative was obtained The ir spectral data suggest that the complexes contain RSeO2− ligands acting as bidentate in O,O′-seleninato complexes, Where possible, a tentative stereochemistry for the complexes is discussed on the basis of the results obtained

Mass spectral investigations on benzeneseleninic acid

Abstract: The mass spectra of benzeneseleninic acid and of diphenyl diselenide have been examined and a full analysis is reported. The fragmentation patterns and the fragment ions are discussed. A molecular-ion peak was not observed for benzeneseleninic acid; instead the ion with highest mass number appeared in a multiplet, with the most intense peak at m/e 314, having a general shape typical of the presence of two selenium atoms and corresponding to the diphenyl diselenide (C6H5–Se–Se–C6H5) ion.

Synthesis and characterization of para- and meta-substituted benzeneseleninato complexes of tin(ii), silver(i) and iron(ii)

Abstract: New complexes of tin(II), silver([) and iron(II) withpara- andmeta-substituted benzeneseleninic acids are reported and studied by chemical analyses, spectroscopic methods, conductivity and magnetic measurements. The complexes, of the type Sn(XC6H4SeO2)2, Ag(XC6H4SeO2) and Fe(H2O)2(XC6H4SeO2)2, were obtained by reaction of SnCl2, · 2 H2O. AgNO3 and Fe(NH4)2(SO4)2·6 H2O with the sodium benzeneseleninates, XC6H4SeO2Na (X = H.p-Cl,m-Cl,p-Br,m-Br orp-Me). The i.r. spectral data suggest that the silver and iron complexes contain RSeO2− ligands which act as bidentates in O,O′-seleninato complexes. All the iron complexes have a distorted octahedralD4h symmetry. The number of bands in the i.r. spectra of the tin derivatives indicates that there is no equivalence in the manner in which the two seleninato ligands are bonded. We could suggest that the tin atoms are intermolecularly O.O′-bonded via one RSeO2− group, whereas the second ligand is coordinated to the metal via one oxygen atom forming polymeric Ψ-tetrahedral derivatives.

Mass spectral investigations on benzeneseleninic acid

Abstract: The mass spectra of benzeneseleninic acid and of diphenyl diselenide have been examined and a full analysis is reported. The fragmentation patterns and the fragment ions are discussed. A molecular-ion peak was not observed for benzeneseleninic acid; instead the ion with highest mass number appeared in a multiplet, with the most intense peak at m/e 314, having a general shape typical of the presence of two selenium atoms and corresponding to the diphenyl diselenide (C6H5–Se–Se–C6H5) ion.