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  • 1
    Electronic Resource
    Electronic Resource
    Aluminium Hydrazides: Reactions of tert-Butylaluminium Chlorides with Dilithium Bis(trimethylsilyl)hydrazide - Formation of Iminoalanes and their Hydrazido Adducts (1999)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 2021-2027 
    Details
    ISSN: 1434-1948
    Keywords: Aluminium ; Hydrazides ; Alanes ; Lithium ; Imino compounds ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Di(tert-butyl)aluminium chloride reacted with dilithium bis(trimethylsilyl)hydrazide with the formation of a novel Al2Li2N4 cage compound 1. Its structure consists of a dimeric iminoalane RAl(μN-SiMe3)2AlR (R = CMe3), which is bridged by a dilithiumhydrazido ligand with an intact N-N bond. A heterocubane-type molecule is formed, in which two vertices are occupied by Al atoms, two by Li atoms and four by N atoms. One face of the cube is strongly distorted due to the short N-N distance of the hydrazido group. A similar compound, 3, was formed with bis(neopentyl)aluminium chloride but it was isolated in very poor yield. The reaction of Li2N2(SiMe3)2 with (Me3C)2AlCl in the presence of THF yielded an adduct 2, in which each Li atom of the cage is additionally coordinated via Li-Cl-Al bridges to the ligand (Me3Al)2Cl·THF. The reaction of dilithium bis(trimethylsilyl)hydrazide with tert-butylaluminium dichloride gave, by complete cleavage of the hydrazido groups, a dimeric iminoalane [Me3C(THF)AlNSiMe3]2 (4), in which each aluminium atom is coordinated to one THF molecule. Its uncoordinated, solvent-free form 5 was obtained by heating solid 4 to 150 °C in vacuo for several hours. It was identified as the tetrameric iminoalane (Me3CAlNSiMe3)4, which does not adopt the expected heterocubane-type structure, but consists of three anellated four-membered Al2N2 heterocycles in a kind of ladder structure. Remarkably, the cage compound 1 could not be obtained by the reaction of an excess of lithium hydrazide with the iminoalanes 4 and 5. All compounds 1-5 were characterized by crystal structure determinations.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    A Methylene-Bridged Dialuminium Compound as a Chelating Lewis Acid: Complexation of Nitrite and Nitrate Anions by R2Al-CH2-AlR2[R = CH(SiMe3)2]⋆ (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 921-926 
    Details
    ISSN: 1434-1948
    Keywords: Aluminium ; Chelates ; Lewis acids ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Sodium nitrite (NaNO2) dissolves readily in THF, when the methylene-bridged dialuminium compound R2Al-CH2-AlR2 [R = CH(SiMe3)2] 1 with two coordinatively unsaturated aluminium atoms is added. Compound 1 reacts as a chelating Lewis acid, and, as shown by a crystal structure deter-mination of the [Na([18]crown-6)(Et2O)]+ derivative 5c, a compound (5) is formed, in which one oxygen atom and the nitrogen atom of the nitrite ion are each coordinated by one aluminium atom to form a five-membered Al2CNO hetero-cycle. The second oxygen atom of the nitrite anion is not affected. Similarly, lithium nitrate (LiNO3) reacts with 1 to yield a THF soluble product (6a). Single crystals were obtain-ed of the [Li(N,N′,N′′-trimethyltriazinane)2]+ derivative 6c, whose structure shows each aluminium atom to be coordinated by one oxygen atom of the nitrate ion to give a six-membered Al2CNO2 heterocycle.
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  • 3
    Electronic Resource
    Electronic Resource
    The Reaction of Diazomethane Derivatives with the Dielement Compounds R2Al-AlR2 and R2Ga-GaR2 [R = CH(SiMe3)2] - Insertion versus Fragmentation (1999)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 201-207 
    Details
    ISSN: 1434-1948
    Keywords: Aluminium ; Gallium ; Low-valent compounds ; Insertion reactions ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Tetrakis[bis(trimethylsilyl)methyl]dialane(4) 1 reacted with trimethylsilyldiazomethane and bis(trimethylsilyl)diazomethane at room temperature by the insertion of the terminal nitrogen atoms into its aluminium-aluminium bond. As shown by a crystal structure determination, one of the aluminium atoms of each product enhanced its coordination number to four by the interaction with the central nitrogen atom of the C=N-N group, which results in the formation of a three-membered AlN2 heterocycle bearing an exocyclic N=C double bond. The reactions of the corresponding gallium compound (2) containing a gallium-gallium single bond needed more drastic conditions. Mixtures of many unknown products were formed, and only on treatment with trimethylsilyldiazomethane two compounds could be isolated after repeated recrystallization in yields below 10%, which were characterized by crystal structure determinations. One was identified as the trimeric dialkylgallium cyanide (8) with a nine-membered Ga3C3N3 heterocycle, and the other one (9) has a dialkylgallium fragment coordinated by both terminal nitrogen atoms of the chelating ligand NH2-N=C(SiMe3)-NH-. Due to the NMR spectroscopic characterization, 8 seems to be tetrameric in solution with an asymmetric structure containing four different gallium atoms. With this unusual structure, the IR spectrum of tetrameric dimethylgallium cyanide could now completely be interpreted, which was published more than 20 years ago.
    Additional Material: 3 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Diazomethane Derivatives Bearing Dialkylaluminium or DialkylgalliumSubstituents - The Isomeric Diazomethane and Nitrile Imine Structures Realized by the Different Coordination Behavior of Aluminium and Gallium (1999)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 771-776 
    Details
    ISSN: 1434-1948
    Keywords: Aluminium ; Gallium ; Diazo compounds ; Dimerization ; Coordination modes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Lithium trimethylsilyldiazomethanide Li(SiMe3)CN2 reacted with the dialkylaluminium or -gallium halides R2AlCl and R2GaBr [R = CH(SiMe3)2] by the elimination of lithium halide and the formation of the corresponding aluminium or gallium diazo compounds. As shown by a crystal structure determination, the gallium derivative 1 adopts the nitrile imine structure, in which the gallium atom is coordinated by the terminal nitrogen atom of the diazo group. The N-N-C-Si moiety is almost ideally linear with N-N and C-N bond lengths of 125.5 and 115.9 pm on average. In contrast, the diazomethane structure was formed with dialkylaluminium chloride, and the aluminium atom in 2 is attached to the carbon atom of diazomethane. The almost linear N-N-C group (174.1°) has N-N and N-C distances of 120.0 and 126.4 pm, respectively, inverse to that of the gallium derivative. The bonding situations can best be described by the resonance structures R-C≡N+-N--GaR2 for 1 and R2Al-(R)C=N+=N- for 2. The nitrile imine isomer of the aluminium compound could be detected by NMR spectroscopy as a by-product. Both compounds gave dimers in the solid state, a Ga2N2 four-membered heterocycle was formed of 1, while an eight-membered Al2C2N4 heterocycle resulted with 2.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Aluminium Atoms at High Connectivity Sites in Polyhedral Polyborane Analogous Clusters: From Aluminaboranes to Carbaalanes (2000)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 2000 (2000), S. 1-11 
    Details
    ISSN: 1434-1948
    Keywords: Carbaalanes ; Cluster compounds ; Electron deficiency ; Aluminium ; Boron ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cluster chemistry in the third main group has long been restricted to compounds of the lightest element boron. However, about 30 years ago the first compounds were synthesized and characterized in which single aluminium atoms adopted positions of high connectivity in polyhedral borane or carbaborane clusters. The next successful step in these efforts to establish a chemistry analogous to that of the polyboranes with the heavier elements of the third main-group was the synthesis of closo-dodecaaluminate [Al12iBu12]2- at the beginning of the nineties, which was the first homonuclear aluminium analogue of a polyborate anion and had a core exclusively formed by aluminium atoms. Another class of interesting new aluminium compounds was formed by the carbaalanes, which were synthesized and characterized for the first time only recently. They have clusters of aluminium and carbon atoms, and are similar to the carbaborane analogues in that their structures seem to be determined by the number of electron pairs in their molecular centers in accordance with the Wade rules.
    Additional Material: 9 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Die Reaktionen von R2Al—AlR2 und R2In—InR2 mit Benzoesäure - Synthese und Kristallstruktur von R2Al(μ-H)(μ-O2C—C6H5)AlR2 und RIn(μ-O2C—C6H5)4InR [R = CH(SiMe3)2]Professor Joachim Strähle zum 60. Geburtstag gewidmet (1997)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 623 (1997), S. 883-891 
    Details
    ISSN: 0044-2313
    Keywords: Aluminium ; indium ; Al—Al bond ; In—In bond ; benzoato bridges ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The Reactions of R2Al—AlR2 and R2In—InR2 with Benzoic Acid - Synthesis and Crystal Structure of R2Al(μ-H)(μ-O2C—C6H5)AlR2 and RIn(μ-O2C—C6H5)4InR [R = CH(SiMe3)2]Tetrakis[bis(trimethylsilyl)methyl]dialane(4) 1 reacts with benzoic acid by the oxidative cleavage of the Al—Al bond: The Al atoms are inserted into the O—H bond of the acid and the proton is reduced to a hydride anion. As shown by a crystal structure determination, the product 4 shown an unprecedented structure with both dialkylaluminium fragments unsymmetrically bridged by the hydrogen atom and a benzoato group. 4 can be described as a model compound for the first step of the hydrolysis of compounds with low-valent Al atoms as well as elemental aluminium itself. The diindane(4) analogue of 1 (2) and benzoic acid yield, however, elemental indium and mixed alkyl benzoato indium derivatives, from which bis(trimethylsilyl)methyldi(benzoato)indium 9 has been characterized by a crystal structure determination. 9 consists of a dimer with a remarkable cage structure, in which both monoalkylindium groups are interconnected by four benzoato-O,O′ bridges.
    Notes: Tetrakis[bis(trimethylsilyl)methyl]dialan(4) 1 reagiert mit Benzoesäure unter oxidativer Öffnung der Al—Al-Bindung, wobei sich formal die Al-Atome in die O—H-Bindung der Säure einschieben und das Proton zu einem Hydridion reduzieren. Die beiden Dialkylaluminium-Fragmente des daraus erhaltenen Produkts 4 werden, wie durch Kristallstrukturbestimmung gezeigt wird, in bisher unbekannter Weise durch das Wasserstoffatom und eine Benzoatogruppe unsymmetrisch miteinander verbrückt. 4 läßt sich als Modellverbindung für die erste Stufe der Hydrolyse von Derivaten mit niederwertigen Al-Atomen und elementarem Aluminium beschreiben. Das zu 1 analoge Diindan(4) 2 ergibt dagegen mit Benzoesäuren unter Abscheidung von elementarem Indium gemischte Alkyl-benzoatoindium-Verbindungen. Bis(trimethylsilyl)methyl-di(benzoato)indium 9 wird kristallstrukturanalytisch untersucht; es liegt als Dimeres mit einer Käfigstruktur vor, in der zwei Monoalkylindium-Reste über vier Benzoato-O,O′-Brücken miteinander verbunden werden.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.199762301139
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