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  • 1
    ISSN: 1434-4475
    Keywords: Keywords. Density functional study; Silicon compounds; Metal silyl complexes; Anionic metal complexes.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung.  Der Einfluß des Substitutionsmusters des Silylliganden wurde für Komplexe des Typs (CO)4Fe(H)SiR 3 und der korrespondierenden Anionen [(CO)4FeSiR 3]− durch eine Dichtefunktional-Studie untersucht. Schrittweise Substitution von R=H gegen R=Cl führt bei beiden Komplextypen zu einer Verkürzung der Fe-Si-Bindung. Der Substitutionseffekt ist bei den anionischen Komplexen viel größer, was durch die stärkere Rückbindung vom Metallzentrum zum SiR 3-Ligand erklärt wird. Die optimierten Strukturen der Komplexe stimmen gut mit experimentell ermittelten überein. Die Elektronendichteänderungen werden auch in den berechneten Schwingungsfrequenzen der CO-Liganden und den Protonenaffinitäten der anionischen Komplexe widergespiegelt. Zunehmender Elektronenabzug durch die Silylliganden verringert die Protonenaffinität.
    Notes: Summary.  The effect of the substitution pattern at the silyl ligand in complexes of the type (CO)4Fe(H)SiR 3 and the corresponding anions [(CO)4FeSiR 3]− was investigated by a density functional study. Upon successive substitution of R=H for R=Cl, a contraction of the Fe–Si bond takes place in both types of complexes. The effect of the substitution is much larger in the anionic complexes which is explained by a higher degree of back bonding from the metal center to the SiR 3 ligand. The optimized structures of the complexes are in good agreement with related experimental ones. The changes in electron density at the metal center are also reflected in calculated vibrational frequencies of the CO ligands and the proton affinities of the anionic complexes. An increasing electron withdrawal by the silyl ligand lowers the proton affinity.
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  • 2
    ISSN: 1434-4475
    Keywords: Keywords. Hypervalency; Tin compounds; X-Ray structure analysis.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung.  Es wurden neue Organozinnderivate ArNSn(X)RR′ (ArN=2-Me2NCH2C6H4; X=Cl, H, OMe; R,R′=Me, Ph) sowie ArNSnCl2Ph und (ArN)4Sn synthetisiert und hinsichtlich intramolekularer Sn*N-Wechselwirkungen untersucht. Die Bildung der Methoxyderivate ArNSn(OMe)RR′ durch Reaktion von ArNSn(H)RR′ mit Methanol wird mit zunehmender Substitution von Methyl- durch Phenylgruppen schwieriger. Die Molekülstrukturen von ArNSnClMe2, ArNSnCl2Ph und (ArN)4Sn wurden durch Röntgenbeugung bestimmt. ArNSnClMe2 und ArNSnCl2Ph sind trigonal-bipyramidal gebaut, wobei die Sn*N-Wechselwirkung bei ArNSnClMe2 stärker ist als bei ArNSnCl2Ph. Bei (ArN)4Sn findet man in Kristall zwei kristallographisch unterschiedliche Moleküle mit schwachen Sn*N-Wechselwirkungen beider Aminogruppen. Sie unterscheiden sich durch die relative Position der Aminogruppen.
    Notes: Summary.  New organotin derivatives ArNSn(X)RR′ (ArN=2-Me2NCH2C6H4; X= Cl, H, OMe; R, R′=Me, Ph) as well as ArNSnCl2Ph and (ArN)4Sn were prepared and investigated with regard to intramolecular Sn*N interaction. The formation of the methoxy derivatives ArNSn(OMe)RR′ by reaction of ArNSn(H)RR′ with methanol is rendered more difficult by successive replacement of the methyl substituents by phenyl groups. The molecular structures of ArNSnClMe2, ArNSnCl2Ph, and (ArN)4Sn were determined by X-ray diffraction. ArNSnClMe2 and ArNSnCl2Ph have a trigonal bipyramidal structure, the Sn*N interaction being stronger in ArNSnClMe2 than in ArNSnCl2Ph. There are two crystallographically different molecules in crystalline (ArN)4Sn with weak Sn*N interactions of both amino groups. They differ by the relative position of the amino groups.
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  • 3
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 57 (2001), S. m475-m477 
    ISSN: 1600-5368
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The attempt to crystallize CuIBr(bpy)2, where bpy is bipyridine, from an acetonitrile solution in a glove-box led unexpectedly to a dimeric carbonato-bridged CuII precipitate, viz. μ-carbonato-bis[bis(bipyridine)copper(II)] dibromide diacetonitrile monohydrate, [Cu2(C10H8N2)4(CO3)]Br2·2CH3CN·H2O. The μ2-carbonato ligand is probably the result of an oxidation of traces of CO2 by CuI. The resulting structure contains two square-pyramidally coordinated CuII atoms bridged by a CO32− unit.
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  • 4
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 57 (2001), S. m365-m367 
    ISSN: 1600-5368
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The title compound, di-μ-hydroxo-bis[(1,1,4,7,7-pentamethyldiethylenetriamine)copper(II)] dibromide acetonitrile disolvate, [Cu2(OH)2(C9H23N3)2]Br2·2CH3CN, is the reaction product of CuBr with 1,1,4,7,7-pentamethyldiethylenetriamine (pmdeta) in water-containing acetonitrile. The cation is the dimer of an asymmetrically hydroxo-bridged complex of copper(II) coordinated by 1,1,4,7,7-pentamethyldiethylenetriamine. The centrosymmetric structure contains distorted square-pyramidally coordinated Cu atoms.
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  • 5
    ISSN: 1434-1948
    Keywords: Oxo clusters ; Titanium ; Metal alkoxides ; Sol-gel processes ; Carboxylato complexes ; Solid-state structures ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ti9O8(OPr)4(methacrylate)16 was obtained by the reaction of Ti(OPr)4 with an excess of methacrylic acid and analyzed by X-ray diffraction. The compound consists of a ring of nine [TiO6] octahedra linked by six μ2- and only two μ3-oxide bridges.
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  • 6
    ISSN: 0009-2940
    Keywords: Clusters ; Zirconium ; Metal alkoxides ; Sol-gel processes ; Carboxylato complexes ; Oxo complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The crystalline oxozirconium methacrylate clusters Zr6(O-H)4O4(OMc)12 and Zr4O2(OMc)12 were obtained by reaction of Zr(OnPr)4 with an excess of methacrylic acid and analysed by X-ray diffraction. The oxide and hydroxide groups are in a μ3- bridging mode in both structures, and the methacrylate ligands are chelating or bridging. The zirconium atoms in Zr6(OH)4O4(OMc)12 form an octahedron the cluster having crystalographic C3v symmetry. Each metal atom is square-antiprismatically coordinated by eight oxygen atoms. In Zr4O2(OMc)12, the zirconium atoms have a distorted butterfly arrangement; their coordination geometry is square-antiprismatically coordinated by eight oxygen atomes. In Zr4O2)OMc)12, the zirconium atoms have a distorted butterfly arrangement; their coordination geometry is square-antiprismatic or capped octahedral.
    Additional Material: 6 Ill.
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  • 7
    ISSN: 0009-2940
    Keywords: Stannyl complexes ; Plumbyl complexes ; Tungsten complexes ; Molybdenum complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Transition-Metal Stannyl Complexes, 10 - Molybdocen and Wolframocen Derivatives with Two Different Main-Group-4 LigandsReactions of Li[Cp2MSnPh3] (M = Mo, W) with CH3I, BuBr, PhCH2Br, PhC(O)Cl or Br(CH2)nBr (n = 4,5) yield Cp2M(R)SnPh3 [R = CH3, Bu, CH2Ph, C(O)Ph, (CH2)nBr], while tBuBr or CH3C(O)Cl give the hydrido complexes Cp2M(H)SnPh3. A silyl stannyl complex is only obtained from Li[Cp2WSnPh3] and Me3SiOSO2CF3, but not with Me3SiCl or from the anionic Mo complex. In contrast, the reactions of chlorostannanes provide the bis(stannyl) complexes Cp2M(SnR′3)SnPh3 or Cp2M(SnR′2Cl)SnPh3. R/Cl exchange at the tin atom is observed when an excess of the chlorostannane is used. Upon reaction of Li[Cp2MSnPh3] with Ph3PbCl only Cp2M(PbPh3)SnPh3 is formed, while a mixture of Cp2M(PbMe3)SnPh3 and Cp2M(PbMe2Cl)SnPh3 is obtained with Me3PbCl due to redistribution reactions. The structures of Cp2W(SnPh3)C(O)Ph, Cp2W(SnPh3)SntBu2Cl and Cp2W(SnPh3)PbMe2Cl were determined by X-ray structure analyses.
    Additional Material: 1 Tab.
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