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  • 1
    Electronic Resource
    Electronic Resource
    Morphological instabilities in pattern formation by precipitation and crystallization processes (1996)
    Springer
    Geologische Rundschau 85 (1996), S. 19-28 
    Details
    ISSN: 0016-7835
    Keywords: Key words Anastomoses ; Crystal zoning ; Snow bands ; Liesegang rings ; Ostwald ripening ; Self organization ; Siderite ; Supersaturation theory ; Zebra rock
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  Morphological instabilities in periodic patterns occurring both in precipitation and crystallization processes (Liesegang rings and crystal zoning) are investigated and compared with similar patterns in geological samples (zebra rocks and mud bands in snow sediments). In classical Liesegang systems, undisturbed parallel or concentric precipitation bands are emanated from even or concentric diffusion sources in homogeneous diffusion matrices of gelatine or other gels. In the case of superposing diffusion sources, sources with undulatory curvatures or local diffusion barriers there may occur several types of instabilities within the sequence of regular patterns: (a) gaps within the bands forming radial alleys free of precipitate, (b) transition from broken bands to speckled patterns and (c) apparent branching of bands linked together by so-called anastomoses. Calculations with a competitive particle growth (CPG) model show that lateral instabilities in Liesegang bands (gaps and radial alleys of gaps) are the result of Ostwald ripening effects taking place after precipitation. Apparent branching of bands or formation of anastomoses can be simulated with a prenucleation model according to Ostwald's supersaturation theory. Similar irregularities can be observed in zebra rocks (e.g. banded siderite) whose bandings are commonly explained by sequential sedimentation processes. A very different mechanism is assumed to be responsible for the origin of mud bands in snow sediments. An initially homogeneous distribution of intrinsic mud in snow sediments can be arranged into parallel bands according to a crystal zoning mechanism which is based on repeated thawing and freezing of the snow sediment due to the daily alternation of sun and darkness.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00192056
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  • 2
    Electronic Resource
    Electronic Resource
    Self-organization of recent rhythmic iron–manganese precipitations in underground mines in the Harz mountains (1996)
    Springer
    Geologische Rundschau 85 (1996), S. 29-37 
    Details
    ISSN: 0016-7835
    Keywords: Key words Banded mineralization ; Harz mountains ; Self-organization ; Iron ; manganese ; ferrihydrite ; birnessite ; Time-series analysis ; Aquatic systems ; Iron bacteria ; Ostwald ripening
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  A recent early diagenetic banded iron–manganese mud has been forming underground in a closed lead–zinc mine for approximately 40 years. The processes leading to the banded structure of the precipitate were studied during a period of 2 years. Therefore, 19 physical and chemical parameters were measured regularly in short intervals. The resulting time series were analysed with respect to the data sets of the monthly chemical analyses of the descendent mine water, the daily rainfall and the mineral content. The results reveal that the precipitated material undergoes internal self-organization due to interaction of redox, colloid-chemical, microbial, electrical and ripening processes, and not exclusively produced by seasonal fluctuations of material input. Thus, the primary banding of the material, caused by externally forced fluctuations of the redox conditions within the mine water, is reorganized after a short time. The finally observed bands are controlled by non-linear coupling of reaction and transport processes within the mud. A genetic model for the banded mineralization was developed and verified by numerical simulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00192057
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  • 3
    Electronic Resource
    Electronic Resource
    Morphological instabilities in pattern formation by precipitation and crystallization processes (1996)
    Springer
    International journal of earth sciences 85 (1996), S. 19-28 
    Details
    ISSN: 1437-3262
    Keywords: Anastomoses ; Crystal zoning ; Snow bands ; Liesegang rings ; Ostwald ripening ; Self organization ; Siderite ; Supersaturation theory ; Zebra rock
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Morphological instabilities in periodic patterns occurring both in precipitation and crystallization processes (Liesegang rings and crystal zoning) are investigated and compared with similar patterns in geological samples (zebra rocks and mud bands in snow sediments). In classical Liesegang systems, undisturbed parallel or concentric precipitation bands are emanated from even or concentric diffusion sources in homogeneous diffusion matrices of gelatine or other gels. In the case of superposing diffusion sources, sources with undulatory curvatures or local diffusion barriers there may occur several types of instabilities within the sequence of regular patterns: (a) gaps within the bands forming radial alleys free of precipitate, (b) transition from broken bands to speckled patterns and (c) apparent branching of bands linked together by so-called anastomoses. Calculations with a competitive particle growth (CPG) model show that lateral instabilities in Liesegang bands (gaps and radial alleys of gaps) are the result of Ostwald ripening effects taking place after precipitation. Apparent branching of bands or formation of anastomoses can be simulated with a prenucleation model according to Ostwald's supersaturation theory. Similar irregularities can be observed in zebra rocks (e.g. banded siderite) whose bandings are commonly explained by sequential sedimentation processes. A very different mechanism is assumed to be responsible for the origin of mud bands in snow sediments. An initially homogeneous distribution of intrinsic mud in snow sediments can be arranged into parallel bands according to a crystal zoning mechanism which is based on repeated thawing and freezing of the snow sediment due to the daily alternation of sun and darkness.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00192056
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  • 4
    Electronic Resource
    Electronic Resource
    Self-organization of recent rhythmic iron-manganese precipitations in underground mines in the Harz mountains (1996)
    Springer
    International journal of earth sciences 85 (1996), S. 29-37 
    Details
    ISSN: 1437-3262
    Keywords: Banded mineralization ; Harz mountains ; Self-organization ; Iron, manganese, ferrihydrite, birnessite ; Time-series analysis ; Aquatic systems ; Iron bacteria ; Ostwald ripening
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract A recent early diagenetic banded iron-manganese mud has been forming underground in a closed lead-zinc mine for approximately 40 years. The processes leading to the banded structure of the precipitate were studied during a period of 2 years. Therefore, 19 physical and chemical parameters were measured regularly in short intervals. The resulting time series were analysed with respect to the data sets of the monthly chemical analyses of the descendent mine water, the daily rainfall and the mineral content. The results reveal that the precipitated material undergoes internal self-organization due to interaction of redox, colloid-chemical, microbial, electrical and ripening processes, and not exclusively produced by seasonal fluctuations of material input. Thus, the primary banding of the material, caused by externally forced fluctuations of the redox conditions within the mine water, is reorganized after a short time. The finally observed bands are controlled by non-linear coupling of reaction and transport processes within the mud. A genetic model for the banded mineralization was developed and verified by numerical simulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00192057
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  • 5
    Electronic Resource
    Electronic Resource
    Beiträge zur Chemie der Alkylverbindungen von Übergangsmetallen. XX. [1]. Zur Reaktion von NiCl2 · 2PR3 und CoCl2 · 2PR3 mit LiSn(CH2C6H5)3 (1976)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 425 (1976), S. 151-154 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Contributions to the Chemistry of Transition Metal Alkyl Compounds. XX. On the Reaction of NiCl2 · 2 PR3 and CoCl2 · 2 PR3 with LiSn(CH2C6H5)3LiSn(CH2C6H5)3 reacts with NiCl2 · 2 P(n-C4H9)3 in tetrahydrofuran forming benzyl nickel chloride, which could be isolated in form of the bipyridyl complex C6H5CH2-NiCl · dipy. NiCl2 · 2 P(C6H5)3 and CoCl2 · 2 P(C6H5)3 are reduced to complexes of the formula MCl · 2 P(C6H5)3 · 3 THF (M = Ni, Co).
    Notes: LiSn(CH2C6H5)3 reagiert mit NiCl2 · 2 P(n-C4H9)3 in Tetrahydrofuran zu Benzylnickelchlorid, das als Dipyridylkomplex isoliert werden konnte. Bei Einsatz von NiCl2 · 2 P(C6H5)3 und CoCl2 · 2 P(C6H5)3 erfolgt dagegen eine Reduktion zu Komplexen der Zusammensetzung MCl · 2 P(C6H5)3 · 3 THF (M = Ni, Co).
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19764250209
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  • 6
    Electronic Resource
    Electronic Resource
    Beiträge zur Chemie der Alkylverbindugen von Übergangsmetallen. XXIX. Dibenzylmangan - Darstellung und Reaktionen (1979)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 455 (1979), S. 3-12 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Contributions to the Chemistry of Transition Metal Alkyl Compounds. XXIX. Dibenzyl Manganese - Preparation and ReactionsManganese(II) acetylacetonate reacts with tribenzyl aluminium and dibenzyl magnesium forming the yellow complexes 3(C6H5CH2)2Mn · Al(acac)3 and (C6H5CH2)2Mn · Mg(acac)2 Dibenzyl manganese is also formed at the reaction of dibenzyl magnesium or benzyl magnesium chloride with MnCl2 · 1.5 THF and was separated as the dioxan complex (C6H5CH2)2Mn · 2C4H8O2, the ligands of which can be removed to a great extent in vacuum.Dibenzyl manganese reacts with CO2, CS2 and SO2 with insertion into the Mn-C-bonds. The corresponding manganese compounds were isolated and furtherly characterized.
    Notes: Mangan(II)-acetylacetonat reagiert mit Tribenzylaluminium bzw. Dibenzylmagnesium zu den gelben Komplexen 3(C6H5CH2)2Mn · Al(acac)3 bzw. (C6H5CH2)2Mn Mg(acac)2. Dibenzylmangan entsteht auch bei Einwirkung von Dibenzylmagnesium oder Benzyl magnesiumchlorid auf MnCl2 · 1,5 THF; eine Abtrennung von den Magnesiumsalzen gelingt in Form des 1,4-Dioxankomplexes (C6H5CH2)2Mn · 2C4H8O2, dessen Ligandenmoleküle im Vakuum weit gehend entfernt werden können.Dibenzylmangan reagiert mit CO2, CS2 und SO2 unter Insertion in die Mn-C-Bindungen. Die entsprechenden Mangansalze wurden isoliert und näher charakterisiert.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19794550101
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  • 7
    Electronic Resource
    Electronic Resource
    Beiträge zur Chemie der Alkylverbindungen von Übergangsmetallen. XXXVII. Zur Existenz von 1-Norbornylverbindungen des Wolframs und Molybdäns (1984)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 508 (1984), S. 50-54 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Contributions to the Chemistry of Transition Metal Alkyl Compounds. XXXVII. About the Existence of 1-Norbornyl Compounds of Tungsten and MolybdenumReactions of WCl6, WCl4, WO2Cl2, WOCl4, MoCl5, and MoO2(acac)2 with 1-Norbornyl lithium (1-NorLi1)) are described. From WCl6 and WCl4 [(1-Nor)2W]n is formed, whereas in dependence of the solvent WO2Cl2 and WOCl4 are transformed into the complexes Li2[1-NorWOCl4] · THF, Li[WOCl4], Li[WO2Cl2], and Li2[WO2Cl2]. MoCl5 and MoO2(acac)2 are reduced with formation of Li[MoCl5], Li[MoO2(acac)2] and Li2[MoO2(acac)2].  -  Stable (1-Nor)4M-derivatives of molybdenum and tungsten, comparable those of 3d-metals (M = Ti—Co) seem not to exist.
    Notes: Es wird über Reaktionen von WCl6, WCl4, WO2Cl2, WOCl4, MoCl5 und MoO2(acac)2) mit 1-Norbornyllithium (1-NorLi1)) berichtet. Ausgehend von WCl6 und WCl4 wird [(1-Nor)2W]n gebildet, während WO2Cl2 und WOCl4 je nach Lösungsmittel Komplexe der Formeln Li2[1-NorWOCl4] · THF, Li[WOCl4], Li[WO2Cl2] und Li2[WO2Cl2] ergeben. MoCl5 und MoO2(acac)2 werden zu Li[MoCl5], Li[MoO2(acac)2] und Li2[MoO2(acac)2] reduziert. - Den stabilen (1-Nor)4M-Derivaten der 3d-Metalle (M = Ti—Co) vergleichbare Verbindungen des Molybdäns und Wolframs scheinen nicht zu existieren.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19845080108
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  • 8
    Electronic Resource
    Electronic Resource
    Beiträge zur Chemie der Alkylverbindungen von Übergangsmetallen. XXXIX. Über 3(N, N-Dimethylamino)propyllanthanoid-Verbindungen (1985)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 521 (1985), S. 57-60 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Contributions to the Chemistry of Transition Metal alkyl Compounds. XXXIX. About 3(N,N-Dimethylamino) propyl Lanthanide CompoundsLaCl3, PrCl3, and ErCl3 react with dimethylaminopropyl lithium (RLi) in tetrahydro-furan as a solvent with formation of complexes of the type Li3[LnR3Cl3]. In a similar way the Li3[CeR6] derivative is formed from CeCl3.The organolanthanide complexes were characterized by elementary analysis, hydrolysis and thermolysis products, the effective magnetic moments and the i.r. spectra.
    Notes: LaCl3, PrCl3, und ErCl3 reagieren mit Dimethylaminopropyllithium (RLi) in Tetrahydrofuran als Lösungsmittel zu Komplexen des Typs Li3[LnR3Cl3]. Die entsprechende Reaktion mit CeCl3 führt dagegen zum Li3[CeR6]-Derivat.Eine nähere Charakterisierung der Verbindungen erfolgte durch Elementaranalysen, ihre Hydrolyse- und Thermolyseprodukte, die effektiven magnetischen Momente und ihre IR-Spektren.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19855210208
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  • 9
    Electronic Resource
    Electronic Resource
    Beiträge zur Chemie der Alkylverbindungen von Übergangsmetallen. XLIX. Reaktionen von Cerium(IV)-acetylacetonat mit Lithium- und Magnesiumorganylen (1986)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 543 (1986), S. 192-198 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Contributions to the Chemistry of Organo Transition Metal Compounds. XLIX. Reactions of Cerium(IV) Acetylacetonate with Organolithium and Organomagnesium CompoundsReacting Ce(acac)4 with lithium organyls RLi (R = CH3 1-Nor1), ((CH3)2NCH2CH2CH2) in the molar ratio 1:1 the cerium compound is reduced with formation of Li[Ce(acac)4]. Using a molar ratio of Ce:Li = 1:4 organocerium complexes of the composition R3Ce · 3 Li(acac) or Li3[R3Ce(acac)3] are formed. From reactions with excess CH3Li (Ce: Li = 1:7) Li3[Ce(CH3)6] · 3 Li(acac) could be isolated.All cerium complexes are characterized by elementary analysis, hydrolysis products, i.r. spectra, and molecular weight determination.
    Notes: Ce(acac)4 reagiert mit Lithiumorganylen RLi (R = CH3, 1-Nor1), ((CH3)2NCH2CH2CH2) im Molverhältnis 1:1 unter Reduktion zum Cerium(III)-Komplex Li[Ce(acac)4]. Wählt man ein Molverhältnis von 1:4, so entstehen Organocerium(III)-Komplexe der Zusammensetzung R3Ce · 3 Li(acac) bzw. Li3[R3Ce(acac)3]. Donormoleküle bewirken keine Abspaltung des Li(acac), sondern werden zusätzlich addiert unter Bildung von Komplexen des Typs Li3[R3Ce(acac)3] · n D (D = THF, n = 2; D = DME, TMED2), n = 1. Bei Reaktionen mit überschüssigem CH3Li (Ce:Li = 1:7) wurde Li3[Ce(CH3)6] · 3 Li(acac) isoliert.Bei Umsetzungen von Ce(acac)4 mit Dibenzyl- und Bis(1-naphthylmethyl)magnesium wurden Cerium(III)-Komplexe der Zusammensetzung Ce(acac)3 · RMg(acac) gebildet.Alle erhaltenen Verbindungen wurden durch ihre Elementaranalysen, Hydrolyseprodukte, IR-Spektren und durch Molmassebestimmungen charakterisiert.Ce(acac)4 reacts with dibenzyl and bis (1-naphthylmethyl) magnesium with formation of complexes of the type Ce(acac)3 · RMg(acac).
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19865431223
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  • 10
    Electronic Resource
    Electronic Resource
    Beiträge zur Chemie der Alkylverbindungen von Übergangsmetallen. 57. 2-(Dimethylaminomethyl)ferrocenyl-Verbindungen von 3d-ElementenProfessor Rudolf Taube zum 60. Geburtstage gewidmet (1991)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 606 (1991), S. 133-139 
    Details
    ISSN: 0044-2313
    Keywords: 2-(Dimethylaminomethyl)ferrocenyl 3 d metal compounds ; preparation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Contributions to the Chemistry of Transition Metal Alkyl Compounds. 57. 2-(Dimethylaminomethyl)ferrocenyl Compounds of 3 d Elements[2-(Dimethylaminomethyl)ferrocenyl]lithium, (FcN)Li (I), reacts with MCl2 · xTHF to (FcN)2Mn (II), (FcN)2Co (III), Li2[Fe(FcN)2Cl2] (IV) as well as with FeCl3 to (FcN)3Fe (V). In the same way the complex (C5H5)2V(FcN) (VI) was obtained from (C5H5)2VCl. When I is reacted with M(acac)3 (M = Cr, Co) only a partial ligand exchange took place  -  independently from the molar ratio of the reactants  -  with formation of (FcN)Cr(acac)2 (VII) and (FcN)Co(acac) (VIII).An intensive characterization of II-VIII was achieved by elementary analysis, determination of molecular weights, IR-, UV-VIS- and 1H-NMR spectra as well as determination of effective magnetic moments.
    Notes: [2-(Dimethylaminomethyl)ferrocenyl]lithium, (FcN)Li (I), reagiert mit MCl2 · xTHF zu (FcN)2Mn (II), (FcN)2Co (III), Li2[Fe(FcN)2Cl2] (IV) sowie mit FeCl3 zu (FcN)3Fe (V). Auf gleiche Weise wurde aus (C5H5)2 VCl der Komplex (C5H5)2V(FcN) (VI) erhalten. Bei der Einwirkung von I auf M(acac)3 (M = Cr, Co) erfolgte unabhängig vom Molverhältnis der Reaktanten nur ein partieller Ligandenaustausch unter Bildung von (FcN)Cr(acac)2 (VII) und (FcN)Co(acac) (VIII).Eine eingehende Charakterisierung von II-VIII erfolgte durch Elementaranalysen, Molmassebestimmungen, IR-, UV-VIS- und 1H-NMR-Spektren sowie Bestimmung der effektiven magnetischen Momente.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19916060114
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