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  • General Chemistry  (22)
  • 1
    Digitale Medien
    Digitale Medien
    Synthesis, Spectroscopy, and Magnetic Properties of Transition-Metal Complexes with the Diethyl 2-Quinolylmethylphosphonate (2-qmpe) Ligand - Crystal Structures of [Ni(2-qmpe)4(H2O)2](ClO4)2 and [Mn(2-qmpe)4(H2O)2](ClO4)2 Showing Unexpected O-Binding of the qmpe Ligands (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 169-175 
    Details
    ISSN: 1434-1948
    Schlagwort(e): Ligand field spectra ; Phosphonate complexes ; X-ray structures ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The synthesis and characterization of transition-metal coordination compounds containing the ligand diethyl 2-quinolylmethylphosphonate (2-qmpe) is described. Complexes of CoII, MnII, NiII, CdII, and ZnII were found to be mutually isomorphous according to their X-ray powder diffraction patterns and IR spectra. The new coordination compounds were identified and characterized by elemental analysis, magnetic measurements, infrared and ligand-field spectra. The crystal structures of the complexes [M(2-qmpe)4(H2O)2](ClO4)2 (M = Ni, 1; Mn, 2) reveal six-coordinate [M(2-qmpe)4(H2O)2] cations with the qmpe ligand coordinating via the oxygen rather than via the nitrogen atom, as well as lattice perchlorate anions. The metal ion is octahedrally surrounded by the four oxygen atoms of the four organic ligands. The non-participation of the pyridine nitrogen atom is unusual. The two water molecules occupy the fifth and the sixth coordination sites in a trans configuration. The coordinated water molecules are strongly hydrogen-bonded to the pyridine nitrogen atom of the 2-qmpe, further stabilizing the solid-state structure. The geometry of the metal ion can be described as distorted octahedral. For the CuII complex, a hydroxo-bridged dinuclear structure of the type [Cu(2-qmpe)2(OH)(H2O)2]2(ClO4)2 is proposed, based on its spectroscopic and magnetic properties. Ligand-field spectra of the Co and Ni compounds were found to be in agreement with the tetragonally distorted octahedral geometry.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    A Unique Copper-Controlled Template Synthesis of Tetradentate N4-Donor Ligands and Their Propeller-Type Linear Trinuclear CuII Complexes (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 547-549 
    Details
    ISSN: 1434-1948
    Schlagwort(e): Copper ; Trinuclear ; Formamidines ; Magnetism ; Crystal structure ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: In situ reaction of CuII triflate with aminopyridine or aminopyrimidine and triethylorthoformate in ethanol results in unique linear trinuclear CuII complexes with the general formula [Cu3(L-)4](CF3SO3)2(EtOH)x (L = dehydronated ligand N,N′-bis(pyridine-2-yl)formamidine or the new ligand N,N′-bis(pyrimidine-2-yl)formamidine). The structure [Cu-Cu-Cu angle 175.19(2)°] consists of four nearly flat molecules of the ligand which contribute to the propeller-type structure around the Cu-Cu-Cu axis. A strong antiferromagnetic interaction between the CuII ions is observed, resulting in an S = 1/2 ground state below 100 K.
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  • 3
    Digitale Medien
    Digitale Medien
    Spontaneous Assembly of a Novel Tetranuclear Ni-Fe Complex by Complete Reshuffling of Ligands and Oxidation States (1999)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 217-219 
    Details
    ISSN: 1434-1948
    Schlagwort(e): Nickel ; Iron ; Clusters ; Carbonyl complexes ; S ligands ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Upon reaction of the mononuclear nickel dithiolate complex [Ni(dsdm)] (H2dsdm = N,N′-dimethyl-N,N′-bis(2-sulfanylethyl)ethylenediamine) with K[HFe(CO)4] in ethanol a unique reshuffling of ligands and of oxidation states takes place. This results in the formation of a novel tetranuclear complex [FeII(dsdm)Ni0(CO)3]2, in which a linear array of Ni-Fe-Fe-Ni is formed. The inner core of this complex consists of the dinuclear [Fe(dsdm)]2, and two Ni(CO)3 groups are bound at the periphery through one of the thiolate sulfurs.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Calcium Ions Do Accelerate the DNA Binding of New Antitumor-Active Platinum Aminophosphonate Complexes (1999)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 1655-1657 
    Details
    ISSN: 1434-1948
    Schlagwort(e): Calcium ; Platinum Complexes ; Aminophosphonate ; Antitumor agents ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The presence of Ca2+ has a marked effect on the reaction kinetics of platinum phosphonate complexes with d(GpG). Compounds studied are [cis-Pt(NH3)2(bmpaa)] and [Pt(R,S-dach)(ntmp)]. The formation of GG-N7,N7 chelates and the release of the phosphonate ligand as observed by NMR is significantly accelerated by the presence of Ca2+, which is ascribed to its interaction with the phosphato groups in the ligands.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    An Unprecedented, Copper-Mediated, In-Situ Multi-Step Ligand Formation - Synthesis, Structure, and Magnetism of Bis(μ-methoxo)bis[nitrato(2-methoxy- methylamino-3-methylpyridine)copper(II)] (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1577-1579 
    Details
    ISSN: 1434-1948
    Schlagwort(e): Copper ; Methoxo-bridged complexes ; Crystal structure ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A novel chelating ligand, synthesized in situ within the coordination sphere of CuII from 2-amino-3-methylpyridine, MeOH, and dioxygen from the air, is found to form a strongly coupled, dinuclear methoxo-bridged CuII compound with the formula [Cu(L)(CH3O)(NO3)]2 (L = 2-methoxymethylamino-3-methylpyridine). The geometry around the copper atom is square pyramidal and the Cu-Cu distance within the dinuclear unit is 3.011(2) Å with an Cu-O-Cu angle of 103.13(8)°. Synthesis, X-ray crystal structure, and magnetism are reported.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    A Dimeric Tetranuclear Copper(II) Compound Assembled through Pentacoordinating Carbonate Anions (1999)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 505-507 
    Details
    ISSN: 1434-1948
    Schlagwort(e): Macrocycle ; Pyrazole ; N-Heterocycle ; Carbonate ; Copper ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The 22-membered macrocycle, spanning four endocyclic pyrazole groups, viz. 1,4,9,14,17,22,27,28,29,30-decaaza-5,13,18,26-tetramethylpentacyclo[24.2.1.14,7.111,14.117,20]triacontane-5,7(28),11(29),12,18,20(30),24(27),25-octaene (22Pz), rendered the tetranuclear compound [Cu4(22Pz)2(CO3)2(MeOH)2](ClO4)4(MeOH)4. The copper(II) ions are in distorted octahedral N3O3 environments. All four pyrazole groups of each macrocycle participate in the coordination of the copper(II) ions. The cationic part of this compound is in fact a dimer of two macrocyclic ligands, each containing two copper(II) ions bridged by two carbonate ions in the highly unusual pentacoordinating fashion.Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2005/1999/98332_s.pdf or from the author.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    A Tetranuclear Platinum Compound Designed to Overcome Cisplatin Resistance (1999)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 1429-1433 
    Details
    ISSN: 1434-1948
    Schlagwort(e): Antitumor drugs ; Platinum ; DNA ; Dendrimers ; L1210 Mouse leukemia ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The synthesis and characterisation of the first generation of a poly(propyleneimine) dendrimer DAB(PA)4, substituted with four trans-diamminechloroplatinum moieties is reported. The compound DAB(PA-tPt-Cl)4 was designed to overcome two problems often associated with cisplatin resistance in cancer cells: (i) deactivation of the platinum species by intracellular thiolates and (ii) improved repair of crosslinks with DNA. The four-armed molecule can be expected to form crosslinks with DNA that are very different from the adducts formed by cisplatin. Also, the tetranuclear compound has four leaving groups, while cisplatin has only two. Therefore, DAB(PA-tPt-Cl)4 would be less susceptible towards inactivation by reaction with intracellular thiolates. A reaction with an excess of the model nucleobase guanosine 5′-monophosphate (GMP) confirmed that the tetranuclear compound is capable of binding a maximum of four nucleobases. Therefore, the inactivation of one or two arms would still leave the molecule with enough reactivity to form crosslinks with DNA. Cytotoxicity tests were performed on two mouse leukemia L1210 cell lines, both sensitive and resistant towards cisplatin, and in seven human tumor cell lines. In all cell lines, the tetranuclear compound showed a low cytotoxicity. It is suggested that the low activity is related to the structure of the compound. Probably the high charge (+6) at physiological pH and its branched structure hamper the molecule in crossing the cell membranes.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Synthesis, Structure, Spectroscopy, and Magnetism of Unique Propeller-Type Linear Trinuclear CuII Complexes with In-situ Prepared Formamidine Ligands (1999)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 2269-2275 
    Details
    ISSN: 1434-1948
    Schlagwort(e): Copper ; Trinuclear complexes ; Formamidines ; Magnetism ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Three new copper(II) linear trinuclear compounds are reported, all of which were synthesized in-situ, with the general formula [Cu3(L)4](CF3SO3)2(Y)x, where L is the dehydronated ligand: N,N′-bis(pyridine-2-yl)formamidine (abbreviated as Hpdf), N,N′-bis(pyrimidine-2-yl)formamidine (abbreviated as Hpmf) and N,N′-bis(5-methylpyridine-2-yl)formamidine (abbreviated as Hmpdf), Y = EtOH or H2O and x = 0.5-1.5. The compounds were characterized by X-ray diffraction, IR, LF, and EPR spectroscopy and by magnetic susceptibility down to 4 K. The structure of the compound [Cu3(pmf)4](CF3SO3)2(H2O)1/2 was determined by X-ray crystallography; it was found to crystallise in the triclinic space group P-1 with a = 8.529(5), b = 15.760(5), c = 19.639(5) Å, α = 101.793(5), β = 101.263(5), γ = 102.389(5)°, Z = 2. The structure [Cu-Cu-Cu angle 174.96(11)°] consists of four nearly flat molecules of the ligand, which contribute to the propeller-type structure around the Cu-Cu-Cu axis. A strong antiferromagnetic interaction between the CuII ions is observed with calculated J values, based on the Hamiltonian H = -2J(S1·S2 + S2·S3) - 2J′·S1·S3, of -174(1) cm-1, -120(1) cm-1, and -167(1) cm-1 for the compounds studied with L = pdf, pmf, and mpdf, respectively. These values are in agreement with an S = 1/2 ground state below temperatures of 120-160 K.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    Synthesis, X-ray Crystal Structure and Magnetism of [NiCl2{(bis(2-benzimidazolyl)propane}]2 · (C2H5OH)2 - A Second Example of a Ferromagnetically Coupled Five-Coordinated High-Spin Dichloro-Bridged Nickel(II) Dimer (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1337-1341 
    Details
    ISSN: 1434-1948
    Schlagwort(e): Crystal structures ; Nickel complexes ; Dinuclear complexes ; Magnetism ; Far-infrared ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The ligand bis(2-benzimidazolyl)propane coordinates to NiII with chloride as an anion, thereby forming a dinuclear compound with the formula: [NiCl2(tbz)2]2(C2H6O)2. This compound crystallizes in the space group P21/c. Each five-coordinated NiII ion has a distorted trigonal bipyramidal environment which consist of two asymmetrically bridging Cl anions with distances of 2.3556(17) and 2.4275(16) Å, a terminal Cl anion with a distance of 2.3496(17) Å and two nitrogen atoms of the ligand with distances of 2.022(4) and 2.000(4) Å. The Ni-Ni distance is 3.5891(12) Å, while the Ni-Cl-Ni angle is 97.23(6)°. The magnetic properties of the compound, as studied in the range 5-280 K, have been fitted with a zero-field splitting parameter D (-14.3 cm-1) and a ferromagnetic exchange between the Ni ions in the dinuclear unit (J = +2.5 cm-1). The title compound appears to be the second example for a five-coordinated ferromagnetic dinuclear NiII compound of this type, and its magnetic properties appear to correlate with the ligand structure. With the availability of an increasing number of examples of such species it appears that antiferromagnetic exchange is found for all cases with the chromophore N2ClNiCl2NiClN2 where the MN2 ring is 5-membered. In the case, where this ring is six-membered, the exchange is ferromagnetic.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    Two Examples of Novel and Unusual Double-Layered, Two-Dimensional CuII Compounds with Bridging 1,3-Bis(1,2,4-triazol-1-yl)propane (2000)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 2000 (2000), S. 121-126 
    Details
    ISSN: 1434-1948
    Schlagwort(e): Polymeric copper complexes ; Group-subgroup relationships ; 2D-sheets ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The synthesis and characterisation of two new polymeric CuII complexes is described, i.e. {[Cu(btp)2(CH3CN)(H2O)](CF3SO3)2}n (1) and {[Cu(btp)2(CH3CN)2](ClO4)2}n (2), in which btp = [1,3-bis(1,2,4-triazol-1-yl)propane]. Compound 1 crystallizes in space group P21/c with a = 11.9337(15) Å, b = 20.108(6) Å, c = 12.748(6) Å, β = 92.247(14)°, and Z = 4. Compound 2 crystallizes in space group Pna21 with a = 18.770(8) Å, b = 12.648(8) Å, and c = 12.019(8) Å. The structures refined to R1 values of 0.0683 for 1 and 0.0846 for 2. In both structures the CuII ions are linked by the bridging ligands, resulting in two-dimensional networks. Two such curved layers are arranged on top of each other with center-to-center of layer distances of 2.12 Å in 1 and 1.98 Å in 2. Such double layers are separated from each other by 10.05 Å in 1 and 9.385 Å in 2. The space between the double layers is occupied with interstitial anions. No significant interaction between CuII ions is observed by EPR and magnetic susceptibility measurements. The compounds form a new class of a lattice engineered system held together by the CuII ions. - The coordination geometry of the copper ions is distorted octahedral, with the equatorial plane formed by the N4 nitrogens of the four triazole groups and the axial sites occupied by solvent molecules; acetonitrile and water in structure 1 and two acetonitrile molecules in structure 2. The two structures are related by a group-subgroup relationship, which appears to be the first such case in supramolecular chemistry. - The Cu-N vibrations in the FIR region are found at 274 cm-1 for 1, and at 276 cm-1 for 2. The ligand-field maxima are observed at about 16·103 cm-1, with a shoulder at about 12·103 cm-1. The νCN stretching vibrations of the acetonitrile molecules are found at 2303 and 2261 cm-1 for 1, and at 2313, 2294, 2278, and 2260 cm-1 for 2.Supporting information for this article is available on the WWW under -//_/_http://www.wiley-vch.de/contents/jc_2005/2000/99211_s.pdf or from the author.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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