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  • 1
    Electronic Resource
    Electronic Resource
    Novel coordination compounds of quinic acid. X-ray diffraction study of copper(II) complexes where the metal ion was a chiral centre (1994)
    Springer
    Transition metal chemistry 19 (1994), S. 575-581 
    Details
    ISSN: 1572-901X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The synthesis and characterization of the following coordination compounds derived from quinic acid (quin) (1): [Cu(quin)Cl(H2O)]n·(H2O)n(2); [Ni(quin)Cl(H2O)]n·(2H2O) n (3); [Co(quin) Cl(H2O)]n·(2H2O)n(4); [Cu(quin) (NO3)(H2O)]n·(2H2O)n(5); [Cu(quin)(AcO)(H2O)]n· (2H2O)n(6); [Cu(quin)H2O]2·2H2O(7); [Co(quin)2]n (8); [Zn(quin)2](9); [Cd(quin)2](10) and [Hg(quin)2]· 4H2O (11) is presented. All of the compounds were characterized by i.r. and u.v. spectroscopy; in addition, (9) and (10) were analysed by n.m.r., and (2), (5) and (7) by X-ray crystallography. Due to the polyfunctionality of quinic acid diverse structures were obtained: (2) –(6) and (8) were polymeric, (7) was dimeric and (9) –(11) were spiranic. In compound (2) the Cu had a distorted octahedral structure; it was a chiral centre with six different substituents and an optically active ligand. Only one stereoisomer (OC-6-25-A) of the 30 possible was observed in the crystal. Compound (5) was also polymeric, the hexacoordinated Cu atom was a chiral centre (OC-6-53C) and only one stereoisomer was observed. It was bonded to three quinic acid ligands in three different coordination modes and each quinic acid was in turn bonded to three different Cu atoms. Each chain was linked to another two chains giving a net structure. Compound (7) was a dimer with two square pyramidal Cu atoms. Two apical water molecules were found in acis arrangement. Each quinic acid ligand was bonded to two Cu atoms which were linked by two oxygen bridges and each Cu atom was bonded to two quinic acid moieties.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00980406
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  • 2
    Electronic Resource
    Electronic Resource
    Coordination behaviour of 2-guanidinobenzimidazole towards cobalt(II), nickel(II), copper(II) and zinc(II). An experimental and theoretical study (1996)
    Springer
    Transition metal chemistry 21 (1996), S. 31-37 
    Details
    ISSN: 1572-901X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The following coordination compounds derived from 2-guanidinobenzimidazole (2GB) (1); [Ni(2GB)2]Cl2· H2O, (2); [Ni(2GB)2]Br2·3H2O, (3); [Ni(2GB)2-(NO3)2, (4); [Ni(2GB)2](OAc)2, (5); [Cu(2GB)Cl2], (6); [Cu(2GB)Br2], (7); [Cu(2GB)2]Br2·2H2O, (8); [Cu(2GB)2](NO3)2·H2O, (9); [Cu(2GB)2](OAc)2· H2O, (10); [Zn(2GB)Cl2]·H2O, (11); [Zn(2GB)Br2]·H2O, (12); [Co(2GB)Cl2(H2O)2]·5H2O, (13); [Co-(2GB)2Cl2]·3H2O, (14); [Co(2GB)2(H2O)2](NO3)2· 4H2O, (15); and [Co(2GB)2(H2O)2](OAc)2, (16) have been synthesized and characterized by i.r. and electronic spectroscopy. In addition (6)–(10) were analysed by e.p.r. The X-ray diffraction structure of compound (4) was obtained. It crystallizes in the monoclinic system, C2/c (a = 22.511(7), b = 6.735(6) and c= 15.345(5)Å, β =115.31(3)°, Z = 4, final R = 0.0360 and R w = 0.0388 for 1167 observed independent reflections). The nickel(II) atom coordinates two ligands in a square-planar geometry through the imidazolic N(3) and the guanidino N(12). The probable ligand isomers involved in the coordination were determined by theoretical calculations, and the possible structures of the coordination compounds were investigated in order to verify that the experimentally proposed structures were stable. Two different types of coordination compounds were found. One, where the ligand is chelating through the imidazolic N(3) and the guanidino N(12), which is the case for most of the complexes [(2)–(13)]. With only one ligand in the coordination sphere, the structure was either tetrahedral (copper and zinc chloride and bromide complexes) or octahedral (cobalt). With two chelating 2GB units a square-planar geometry was stabilized [(2)–(5) and (8)–(10)]. The second type of coordination behaviour was observed in the cobalt compounds [(14)–(16)]. Here the ligand coordinates monodentate through the imidazolic N(3); the structure is tetrahedral.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00166009
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  • 3
    Electronic Resource
    Electronic Resource
    Transition metal compounds of the purinic isomer allopurinol. Part 1 (1990)
    Springer
    Transition metal chemistry 15 (1990), S. 434-438 
    Details
    ISSN: 1572-901X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The synthesis, spectral and magnetic properties of a series of new compounds of CoII, NiII and CuII with the purinic isomer allopurinol (L) are reported. The counterions employed were Cl−, Br−, NO 3 − , SO 4 2− , ClO 4 − and MeCO 2 − . The metal:ligand stoichiometries found for the compounds range from 1∶1 to 1∶3. Allopurinol exhibits two classes of coordination behaviour: neutral monodentate (MII=Co, Ni and Cu; X−=Cl or Br) and monoanionic bidentate for the compound [CuL(OH)]n. The latter was obtained when the counterion used in the syntheses was NO 3 − , SO 4 2− , ClO 4 − or MeCO 2 − . The coordination behaviour of theN-pyrazolic ring atoms may relate to the interaction mode of this heterocyclic fragment with the xanthine oxidase metalloenzyme.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01040771
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  • 4
    Electronic Resource
    Electronic Resource
    Organometallic tin complexes derived from 2-guanidinobenzimidazole (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Heteroatom Chemistry 9 (1998), S. 637-641 
    Details
    ISSN: 1042-7163
    Keywords: Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Coordination compounds derived from 2-guanidinobenzimidazole 1 and R2SnCl2 (2 R = Me, 3 R = Bu, 4 R = Ph), and SnCl4 7 were prepared and their structures investigated by 1H, 13C, 119Sn, 15N NMR, mass spectrometry (FAB or EI), infrared, and elemental analysis. The NMR data suggest pentacoordinated (5 and 6) or hexacoordinated tin atoms 2-4 and 7. In all cases, 2-guanidinobenzimidazole acts as a bidentate ligand. In the solid state, 2-4 and 7 are associated by bridging chlorine atoms in polymeric chains. © 1998 John Wiley & Sons, Inc. Heteroatom Chem 9: 637-641, 1998
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Versatile behavior of 2-guanidinobenzimidazole nitrogen atoms toward protonation, coordination and methylation (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Heteroatom Chemistry 8 (1997), S. 397-410 
    Details
    ISSN: 1042-7163
    Keywords: Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The structure, dynamic behavior, protonation, methylation, and coordination sites of 2-guanidinobenzimidazole 1a were investigated. Structures of compounds [2-guanidinium-1,3,10-trihydrobenzimidazole]sulfate 1b, [2-guanidinium-1,3-dihydro-benzimidazole]sulfate 1c-1d, [2-guanidinium-1,3-dihydro-benzimidazole]tetrafluoroborate 1e, [2-guanidinium-1,3-dihydro-benzimidazole]chloride 1f, [2-guanidinium-1,3-dihydro-benzimidazole] perchlorate 1g, 2-guanidino-1-methyl-benzimidazole 2a, [2-guanidinium-1,3-dimethyl-benzimidazole]iodide 2b, [2-guanidinium-1-methyl-3-hydro-benzimidazole]chloride 2c, [2-guanidinium-1,10-dihydro-benzimidazole]acetate 3, 2-guanidino-1-hydro-3-borane-benzimidazole 4a, 2-guanidino-1-methyl-3-borane-benzimidazole 4b, (2-guanidino-benzimidazole)dimethyltin 5, [bis(2-guanidino-10-hydro-benzimidazole)nickel(II)] 6, and [bis(2-guanidino-1,10-dihydro-benzimidazole)zinc(II)]nitrate 7 were determined based on 1H, 13C, and 15N NMR spectroscopy. The X-ray diffraction structures of 2a, 2b, 3, 6, and 7 were obtained. The results show that 1a has an open structure without an intramolecular hydrogen bond in DMSO or DMF. The imidazolic N-3 is the preferred basic site in solution for protonation, methylation, and coordination and not N-10 as was suggested from semiempirical calculations. Under strong acidic conditions, diprotonation occurs at N-3 and N-10. In the solid state, 3 and 6 were protonated preferently at N10 rather than at N-1. © 1997 John Wiley & Sons, Inc. Heteroatom Chem 8: 397-410, 1997
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    1H, 13C, 15N, 113Cd, 2D 15N—1H and solid-state 13C CP/MAS NMR of Hg and Cd complexes of 4(1H)-quinazolinone-2,3-dihydro-2-thioxo (1993)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 31 (1993), S. 832-835 
    Details
    ISSN: 0749-1581
    Keywords: 1H, 13C, 15N and 113Cd NMR ; Two-dimensional NMR ; CP/MAS NMR ; Hg and Cd complexes 4(1H) -Quinazolinone-2,3-dihydro-2-thioxo ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Cd(II) and Hg(II) complexes of 4(1H)-quinazolinone-2,3-dihydro-2-thioxo (1) and the free ligand were studied by 1D and 2D multinuclear magnetic resonance in solution and 13C cross polarization magic angle spinning NMR in the solid state. Compound 1 adopts only one of five possible tautomeric structures in solution, namely the thiouracyl-like structure. It was found that the metal atom is linked to two molecules of deprotonated 1 by N-1 and coordinated by the sulphur atom. The compounds retain the same structure in the solid state and in dimethyl sulphoxide solution.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260310908
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