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  • 1
    Electronic Resource
    Electronic Resource
    Metal Ion Binding by Amino Acids. Potassium Hydrogen L-Glutamate Monohydrate K(L-GluH)·H2O (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 1001-1004 
    Details
    ISSN: 0009-2940
    Keywords: Amino acid complexes ; L-Glutamate complexes ; Hydrogen L-glutamate complexes ; Potassium hydrogen L-glutamate ; Hydrogen bonding ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title compound is obtained by neutralization of aqueous solutions of L-glutamic acid with potassium hydroxide, and crystallization from aqueous methanol. The compound shows a pH of 7 in water at ambient temperature and an optical rotation [α]20D of -4.30 (c = 3.0). In the crystal (orthorhombic, space group P212121) the potassium ion is in a distorted trigonal-prismatic environment of six oxygen atoms of four different amino acids and of the water molecule. No nitrogen coordination is observed. Through the bridging function of some of the α-carboxylate oxygen atoms (O1, O2) and through complexation of the metal through the γ-carboxylate groups (O3), a layer-coordination polymer, with strings of potassium ions running parallel, is formed. The layers are cross-linked by hydrogen bonds involving the ammonium and γ-carboxylate functions as well as the water molecule.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19901230512
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  • 2
    Electronic Resource
    Electronic Resource
    Metal Ion Binding by Dipeptides: Structure of the Product Generated in “Aspartame” Hydrolysis, Sodium cyclo(L-α-Aspartyl-L-phenylalanine) Tetrahydrate, Na[c(L-Asp-L-Phe)] 4H2O (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2743-2746 
    Details
    ISSN: 0009-2940
    Keywords: L-α-Aspartyl-L-phenylalanine, cyclisation of ; Dipeptides, cyclic ; Metal complexation by cyclic dipeptides ; Hydrogen bonding ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ester cleavage of aspartame (L-α-aspartyl-L-phenylalanine methyl ester, 1) by equimolar quantities of NaOH is accompanied by intramolecular cyclisation to sodium 3-benzyl-6-(carboxylatomethyl)-2,5-dioxopiperazine (2). The solid-state structure of the crystalline tetrahydrate has been determined by single-crystal X-ray diffraction analysis. The cations are arranged in strings, and each sodium atom is in a distorted octahedral environment of six oxygen atoms, including a β-carboxylato (O1) and an oxo function (O4) of two different dioxopiperazines and four water molecules. No nitrogen coordination is observed. Through the ligand bridging (O1, O4) of the metals and a set of hydrogen bonds involving the amide and carboxylate groups and all water molecules a three-dimensional network is established.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911241216
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  • 3
    Electronic Resource
    Electronic Resource
    The supramolecular structures of complex tri[gold(I)]sulfonium cations (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 2387-2391 
    Details
    ISSN: 0009-2940
    Keywords: Gold(I) complexes ; Sulfonium salts ; Trigoldsulfonium salts ; Au-Au interactions ; Supramolecular aggregation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Tris[(trimethylphosphane)gold(I)]sulfonium tetrafluoroborate (1) has been prepared from the corresponding oxonium salt [(Me3P)Au]3O+ BF-4 and bis(trimethylsilyl) sulfide, (Me3Si)2S. The analogous triisopropylphosphane and methyldiphenylphosphane complexes (2, 3) have been obtained in a similar way. The products are stable crystalline solids, the structure of which has been determined by X-ray methods. They are composed of independent tetrafluoroborate anions and pyramidal tri(gold)sulfonium cations, which are aggregated to form dimeric units (as in 3) or even strings of dimers (as in 1). It is only in complex 2 that steric effects, originating from the bulky phosphane ligands, prevent the building of supra-molecular (supracationic) aggregates. In the independent pyramidal cations of 2 only short intracationic Au…Au contacts have been detected. These are complemented by intercationic gold-gold contacts of similar length in the structures of 1 and 3. - In the preparation of complex 1, the species [(Me3P)Au]4S2+ (BF-4)2 (4) with hypercoordinate sulfur atoms has also been detected by mass spectroscopy.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941271208
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  • 4
    Electronic Resource
    Electronic Resource
    Preparation and Crystal Structures of Gold(I) Complexes of a Series of Benzenethiolates: Pair Formation by Gold-to-Gold Interactions of (Benzenethiolato)(triphenylphosphane)gold(I) (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 605-610 
    Details
    ISSN: 0009-2940
    Keywords: Gold(I) complexes ; Gold(I) thiolates ; Thiolato complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chloro(triphenylphosphane)gold(I) reacts readily with benzenethiol C6H5SH and a series of sterically hindered (2,4,6-trialkylbenzene)thiols 2,4,6-R3C6H2SH in the presence of NEt3 to yield stable gold(I) complexes Ph3PAu(S - 2,4,6-C6H2R3) [R=H (1), Me (2), Et (3), iPr (4)]. The crystal structures of these complexes have been determined by single-crystal X-ray diffraction analysis. In all compounds the gold atoms are linearly two-coordinate with very similar bond lengths and angles. - While complexes 2 - 4 with bulky thiolate ligands are monomeric in the crystal lattice, complex 1 has been found to form pairs of molecules with intermolecular gold - gold contacts of 313.5(5) pm. The Mössbauer spectra of the complexes exhibit large isomer shifts (I.S.), ranging from 3.06 to 3.72 mm s-1, and quadrupole splittings (Q.S.), ranging from 7.90 to 8.68 mm s-1. These data can be attributed to the strong electron-donating properties of the benzenethiolate ligands. The gold - gold contacts in complex 1 lead to I.S. and Q.S. values which are slightly smaller than those of 2 - 4. The Au - S distances do not show a major influence of the S - Au - P pairing in complex 1 as compared to complexes 2 - 4.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260310
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