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  • 1
    ISSN: 0044-2313
    Keywords: Thiooxalates ; 1,1-Dithiooxalate ; 1,1-Dithiooxalic ester ; transition metal complex ; Crystal structures ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 1,1-Dithiooxalic Acid Derivatives as Ligands in Transition Metal Complexes: Structure of O-Methyl-1,1-dithiooxalato-bis(triphenylphosphine)copper(I) and silver(I)Despite O-Alkyl-1,1-dithiooxalates are also tetradentate thioligands their tendency towards the formation of multi-nuclear bridged chelates as found for the basic 1,1-dithiooxalate does practically not exist because of derivatisation. The reaction with triphenylposphinemetal(I)-halogenides yields defined mono-nuclear mixed ligand complexes: O-Methyl-1,1-dithiooxalato-bis(triphenylphosphine)copper(I) (2) and silver(I) (1). X-ray analysis shows that both complexes (1 and 2) are isostructural and crystallize in the monoclinic space group P21/n: (Ph3P)2Ag(S2C2O2Me) (1) with a = 12.794(1), b = 21.314(4), c = 13.560(1) Å, β = 97.983(6)°, and (Ph3P)2Cu(S2C2O2Me) (2) with a = 12.622(1), b = 21.196(2), c = 13.426(1) Å, β = 96.533(7)°. These complexes are the first authentic examples of exclusively end-on coordinated thiooxalate.
    Notes: Obwohl potentiell auch vierzähnig, ist die Tendenz von O-Alkyl(bzw. Aryl)-1,1-dithio-oxalaten zur Ausbildung von Brücken in Mehrkern-Chelaten durch die Derivatisierung gegenüber dem Stammliganden 1,1-Dithiooxalat praktisch nicht mehr vorhanden. Durch Umsetzung mit Triphenylphosphinmetall(I)-halogeniden sind definierte einkernige Gemischtligandenkomplexe zugänglich. O-Methyl-1,1-dithiooxalato-bis(triphenylphosphin)kupfer(I) und -silber(I) konnten mittels Röntgenkristallstrukturanalyse strukturell gesichert werden. Beide Komplexe sind isostrukturell und kristallisieren in der monoklinen Raumgruppe P21/n: (Ph3P)2Ag(S2C2O2Me) (1), mit a = 12,794(1), b = 21,314(4), c = 13,560(1) Å, β = 97,983(6)° und (Ph3P)2Cu(S2C2O2Me) (2), mit a = 12,622(1), b = 21,196(2), c = 13,426(1) Å, β = 96,533(7)°. Diese beiden Komplexe sind die ersten strukturell gesicherten Vertreter mit ausschließlich end-on koordiniertem Thiooxalat.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0044-2313
    Keywords: Chelates, Gadolinium(III) ; Stability Constants ; 1H-NMR Relaxivity ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Chelate Formation of N-Tris(2-aminoethyl)amine-N′,N′,N″,N″,N‴,N‴-hexaacetic Acid (H6TTAHA) and N-(Pyrid-2-yl-methyl)ethylenediamine-N,N′,N′-triacetic Acid (H3PEDTA) with Gadolinium(III) - Syntheses, Stability Constants, and NMR-RelaxivitiesThe chelate formation of N-tris(2-aminoethyl)amine-N′,N′,N″,N″,N‴,N‴-hexaacetic acid (H6TTAHA) and N-(pyrid-2-yl-methyl)ethylenediamine-N,N′,N′-triacetic acid (H3PEDTA) with gadolinium(III) has been studied potentiometrically in aqueous solution at 25°C and μ = 0.1 (KCl). [Gd(TTAHA)]3-: 1gβM/ML = 19.0; {H[Gd(TTAHA)]}2-: 1gKH/MHL = 8.30; [Gd(PEDTA)]: 1gβM/ML = 15.56. Both 1 : 1 gadolinium(III) complexes were isolated as Na2H[Gd(C18H24N4O12)] · 3.5 H2O and [Gd(C14H16N3O6)] · 3 H2O, respectively. Their 1H-NMR relaxivities [1 · mmol-1 · s-1] ({H[Gd(TTAHA)]}2-: 9.5; [Gd(PEDTA)]: 8.8) offer promising applications for 1H-NMR imaging.
    Notes: Die Komplexbildung von N-Tris(2-aminoethyl)amin-N′,N′,N″,N″,N‴,N‴-hexaessigsäure (H6TTAHA) und N-(Pyrid-2-yl-methyl)ethylendiamin-N,N′,N′-triessigsäure (H3PEDTA) mit Gadolinium(III) wurde in wässeriger Lösung bei 25°C und μ = 0,1 (KCl) potentiometrisch untersucht. [Gd(TTAHA)]3-: 1gβM/ML = 19,0; {H[Gd(TTAHA)]}2-: 1gKH/MHL = 8,30; [Gd(PEDTA)]: 1gβM/ML = 15,56. Die 1 : 1-Gadolinium(III)-Komplexe wurden im Fall der H6TTAHA als Dinatriumsalz Na2H[Gd(C18H24N4O12)] · 3,5 H2O, bei der H3PEDTA als Neutralkomplex [Gd(C14H16N3O6)] · 3 H2O erhalten. Ihre NMR-Protonenrelaxivitäten [1 · mmol-1 · s-1] ({H[Gd(TTAHA)]}2-; 9,5; [Gd(PEDTA)]: 8,8) eröffnen Anwendungen als Kontrastmittel für die Kernspintomographie.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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