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  • 1
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 621-627 
    ISSN: 1434-1948
    Schlagwort(e): Nickel ; Oxidation ; Phenols ; Structure ; Dynamic NMR spectroscopy ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The reaction of substituted phenols and dioxygen with Ni(PMe3)4 yields the low-spin tetracoordinate diphenolatonickel compounds Ni(OAr)2(PMe3)2 [ArOH = 2-tert-butylphenol (1), 2-tert-butyl-4-methylphenol (2), 2-tert-butyl-6-methylphenol (3), 2,4-di(tert-butyl)phenol (4), 2-tert-butyl-4-methoxophenol (5), 2-chloro-4-tert-butylphenol (6), 2-isopropylphenol (7), 3-tert-butylphenol (8)]. As is revealed by variable temperature 1H- and 13C-NMR spectroscopy the complexes constitute a mixture of two isomers, each of which can be observed separately at lower temperatures when interconversion is slower. An additional 6-carbaldehyde function transforms the phenolate into a chelating ligand, giving rise to a high-spin hexacoordinate compound Ni(OAr)2(PMe3)2 (9). X-ray crystal-structure determinations of 2 and 3 show a trans square-planar structure, and that of 9 shows a trans octahedral arrangement of donor atoms P2O4. Bulky substituents in the 3- or 4-position, or non-demanding substituents in the 2-position, are less effective in stabilizing molecular diphenolatonickel complexes.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 2027-2032 
    ISSN: 1434-1948
    Schlagwort(e): Nickel(0) ; Oxidation ; Phenols ; Structure ; Ion pairs ; Hydrogen bonds ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Admission of molecular oxygen to a solution containing Ni(PMe3)4 and substituted phenols (ArOH) affords bisphenolatonickel compounds trans-Ni(OAr)2(PMe3)2 [ArOH = 2-chlorophenol (1), 2-bromophenol (2), 2,4,6-trichlorophenol (3)]. In the absence of dioxygen the phenols reversibly protonate the nickel complex to form ionic compounds [NiH(PMe3)4]+ Y- containing hydrogen-bonded anions Y = [H2(2-Cl-C6H4O)3] (4), [H(2-OH-C6H4COO)2] (5). As a side-reaction, formal insertion of nickel to give 2-hydroxyphenylnickel compounds Ni(Ar′)X(PMe3)3 [Ar′ = 2-OH-C6H4; × = Br (6), I (7)], trans-Ni(Ar′)Cl(PMe3)2 [Ar′ = 2-OH-3,5-Cl2-C6H2 (8)] and trans-Ni(OAr)Cl(PMe3)2 [Ar = 2,4,6-Cl3-C6H2 (9)] is observed. An X-ray crystal structure determination of 1 shows a trans square planar arrangement of donor atoms, that of 6shows a distorted square pyramid, while 4 contains tetrahedral nickel cations with a delocalized hydrogen atom and triphenolate anions H2(ArO)3-.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Publikationsdatum: 2021-07-24
    Beschreibung: Substantial changes have occurred in the Arctic Ocean in the last decades. Not only sea ice has retreated significantly, but also the ocean at middepth showed a warming tendency. By using simulations we identified a mechanism that intensifies the upward trend in ocean heat supply to the Arctic Ocean through Fram Strait. The reduction in sea ice export through Fram Strait induced by Arctic sea ice decline increases the salinity in the Greenland Sea, which lowers the sea surface height and strengthens the cyclonic gyre circulation in the Nordic Seas. The Atlantic Water volume transport to the Nordic Seas and Arctic Ocean is consequently strengthened. This enhances the warming trend of the Arctic Atlantic Water layer, potentially contributing to the Arctic “Atlantification.” Our study suggests that the Nordic Seas can play the role of a switchyard to influence the heat budget of the Arctic Ocean.
    Schlagwort(e): 551.46 ; Arctic Ocean ; Atlantic Water ; sea ice decline ; Nordic Seas ; Greenland Sea ; Atlantification
    Sprache: Englisch
    Materialart: article
    Standort Signatur Erwartet Verfügbarkeit
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