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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 799-805 
    ISSN: 1434-1948
    Keywords: Aminoalcohol ligands ; Hydrogen bonds ; Magnetic properties ; Oxo complexes ; Vanadium ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The aminoalcohol ligands diethanolamine (H2dea) and triethanolamine (H3tea) react with [VO(acac)2] to yield the tetranuclear oxovanadium(IV) complexes [{VO(dea)}2{VO(acac)}2(μ2-OMe)2] (1) and [{VO(Htea)}2{VO(acac)}2(μ2-OMe)2] (2). In the case of the potentially bridging aminoalcohol ligands N,N,N′,N′-tetrakis(2-hydroxyethyl)ethylenediamine (H4edte) and N,N,N′,N′-tetrakis(2-hydroxypropyl)ethylenediamine (H4edtp) the corresponding oxovanadium(IV) complexes could not be isolated. Instead after air oxidation the ligand supported binuclear oxovanadium(V) complexes [{VO(acac)}2(edte)] (3) and [{VO(acac)}2(edtp)] (4) are obtained. The reaction of the ligand H4edtp with ammonium meta-vanadate in methanol solution leads to the methoxy bridged binuclear oxovanadium(V) complex [(VO)2(edtp)(μ2-OMe)2] (5). The tetranuclear oxovanadium(IV) complexes can be isolated as crystalline compounds 1 · 2 MeOH and 2 · 2 MeOH and have been characterized by IR, UV/Vis, and ESR spectroscopy as well as cyclic voltammetry and magnetic susceptibility measurements. Single-crystal diffraction studies reveal that the complexes 1 and 2 contain a tetranuclear {(VO)4(μ3-OR)2(μ2-OR)4}2+ core composed of three different types of edge-shared binuclear units, whereas the oxovanadium(V) complexes 3, 4, and 5 posses binuclear structures, that are either ligand supported as in the case of 3 and 4 or contain a μ2-methoxy bridged{(VO)2(μ2-OR)2}4+ core as in the case of 5. ESR and magnetic data indicate a singlet ground state for 1 · 2 MeOH and 2 · 2 MeOH, although competing ferromagnetic exchange interactions are operative within the tetranuclear core structure. In the solid state compounds 1 · 2 MeOH and 2 · 2 MeOH hydrogen bridged supramolecular structures are found. The hydrogen bonding scheme of both compounds leads to the formation of a similar chain arrangement of the tetranuclear complexes 1 and 2.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0044-2313
    Keywords: Crystal Structure ; Electronic Structure ; Spectroscopic Data ; Tris(trimethylsilyl)phosphane Complexes ; Vanadium ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis, Crystal Structure, Electronic Structure, Spectroscopic and Magnetic Properties of [VOCl2{P(SiMe3)3}2]: A Phosphane Complex with a Disordered VOCl2 GroupVOCl3 reacts with P(SiMe3)3 to form blue green crystals of [VOCl2{P(SiMe3)3}2] (1). The X-ray crystal structure analysis of 1 (cubic space group P213: a = 1541.4(1) pm, Z = 4) reveals a slightly distorded trigonal bipyramidal coordination environment for the disordered vanadium(IV) center. Density functional calculations on the compound [VOCl2{P(SiH3)3}2] (2) are in accord with this observation. 1 has been characterized by ESR, vibrational (IR and Raman) and electronic absorption spectroscopy and magnetic measurements. The ESR spectra of 1 in a toluene solution (293 K and frozen solution at 6 K) exhibit hyperfine interactions of the unpaired electron with the 51V center (I = 7/2) and the 31P centers (I = 1/2) of the two equivalent phosphane ligands. The ligand-field transitions of the VOCl2{P}2 chromophore observed in the electronic absorption spectrum have been assigned on the basis of density functional calculations on 2.
    Notes: Bei der Umsetzung von VOCl3 mit P(SiMe3)3 werden blaugrüne Kristalle von [VOCl2{P(SiMe3)3}2] (1) erhalten. Die Kristallstrukturanalyse von 1 (kubische Raumgruppe P213: a = 1541,4(1) pm; Z = 4) zeigt für das fehlgeordnete Vanadium(IV)-Zentrum eine leicht verzerrte, trigonalbipyramidale Umgebung, die durch Dichtefunktionalrechnungen an der Stammverbindung [VOCl2{P(SiH3)3}2] (2) bestätigt wird. Zur Charakterisierung von 1 wurden ESR-, Schwingungs- (IR und Raman) und Elektronenanregungsspektren aufgenommen und die magnetische Suszeptibilität bei Zimmertemperatur bestimmt. Die ESR-Spektren einer Lösung von 1 in Toluol (293 K und gefrorene Lösung bei 6 K) zeigen neben der Hyperfeinwechselwirkung des ungepaarten Elektrons mit dem 51V-Zentrum (I = 7/2) auch eine entsprechende Wechselwirkung mit den 31P-Zentren (I = 1/2) der beiden äquivalenten Phosphanliganden. Die Banden des VOCl2{P}2-Chromophors im Elektronenanregungsspektrum von 1 lassen sich mit Hilfe von Dichtefunktionalrechungen an 2 entsprechenden elektronischen Übergängen zuordnen.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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