ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    ISSN: 1434-1948
    Keywords: Metal complexes ; Template synthesis ; Schiff bases ; Oxaazamacrocycles ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New series of macrocyclic Schiff-base lanthanide(III), yttrium(III), and cadmium(II) complexes, [M(1)]Xn (X = NO3-, M = Y, Ln = La-Yb except Pm and Dy; X = ClO4-, M = Cd, La, Ce, Pr, Sm, Gd, or Er) and [M(3)]Xn (X = NO3-, M = Dy; X = ClO4-, M = Er and Cd), have been prepared by cyclocondensation of O1,O7-bis(2-formylphenyl)-1,4,7-trioxaheptane with O1,O7-bis(2-aninyl)-1,4,7-trioxaheptane (1) or tris(2-aminoethyl)amine (3) in the presence of the appropriate metal salt as a template agent. The Schiff-base macrocycles 1 and 3 are also formed in the absence of a metal ion. Treatment of 1 with NaBH4 in methanol gives the diamine macrocycle 2. The reactions of LnIII, CdII, and YIII ions with 2 have also been investigated. The crystal structures of the monoprotonated ligand 2 and of the complex [Cd(3)](ClO4)2 have been determined by X-ray diffraction analysis.Supporting information for this article is available on the WWW under -//_/_http://www.wiley-vch.de/contents/jc_2005/2000/99352_s.pdf or from the author.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1434-1948
    Keywords: Carbene complexes ; Carboxylato complexes ; Density functional calculations ; Palladium ; Rhodium ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The structures of several complexes arising from the interaction between methylene and palladium and rhodium diformates were optimized through density functional calculations. For palladium, mono-, di-, and trimeric complexes were considered. The results obtained show that in all cases the most stable structures correspond to complexes in which methylene has inserted in one of the M-O bonds, while metal-carbene complexes are energy minima only for monomeric palladium diformate and for rhodium diformate. Trimeric palladium formate is thermodynamically stable upon fragmentation. However, when it reacts with methylene, fragmentation becomes favorable. The role of the resulting monomeric complex in the olefin cyclopropanation mechanism catalyzed by palladium dicarboxylates is discussed.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 1434-193X
    Keywords: Allosterism ; Crown compounds ; Molecular receptors ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The preparation of compounds 1-4 as simple systems to display allostery is described. Transport experiments (bulk liquid membrane) of ammonium cations in the presence or absence of ZnI2 in the receiving and donor phases evidenced strong negative or positive allosteric effects of the metal towards ammonium complexation, which depended on the relative arrangement of crowns with respect to the pyrazole nitrogens.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1507-1516 
    ISSN: 1434-193X
    Keywords: Nucleosides ; Nucleosides ; Radical reactions ; Hydrogen transfer ; CH-π interaction ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---A new approach to the synthesis of nucleoside analogs has been developed, which involves initial chemo- and regioselective cohalogenation of 1-N-vinylpyrimidinediones 10a,b using N-bromosuccinimide in the presence of variously substituted propargylic alcohols. Radical carbocyclization of the resulting β-bromo propargylic ethers 17-22 then leads to 3-methylenetetrahydrofurans 23-26. In such cyclizations, different reactivities have been observed for diastereomers 22a,b obtained by cohalogenation with (R)-1-benzyloxybut-3-yn-2-ol; although the expected anti 3-methylenetetrahydrofurans 27a,b were obtained, the syn diastereomers 28a,b were only the minor constituents of a mixture in which bicyclonucleosides 29a,b were the major components. The formation of 29a,b results from a 1,6-hydrogen transfer followed by cyclization, which might be favored by a CH-π interaction in radical intermediate synII.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...