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  • 11
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 2021-2027 
    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.
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  • 12
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 355-360 
    ISSN: 1434-1948
    Keywords: Gallium ; Indium ; Low-valent compounds ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Tetrakis[bis(trimethylsilyl)methyl]digallane(4) (1) with a Ga-Ga single bond and the corresponding diindane(4) 2 with an In-In single bond were treated with different protic reagents: tert-Butyl alcohol did not react with 1 at all, while phenol gave a mixture of unknown products, which could not be separated. The more acidic pentafluorophenol did not react as an acid, but C-F bonds were cleaved to form almost quantitatively the dimer (R2GaF)2 5, which was characterized by a crystal-structure determination. Water and 1 yielded the dimeric dialkylgallium hydroxide 6. The Ga-Ga bond was also cleaved by the reaction of 1 with durylthiophenol (duryl = 2,3,5,6-tetramethylphenyl), which gave two main products: R2Ga(SDuryl) 7 and RGa(SDuryl)2 8. In contrast, the chelating acid dibenzoylmethane reacted by means of a substituent exchange, with the release of two equiv. of bis(trimethylsilyl)methane for each formula unit of 1, to form 9, in which the Ga-Ga bond is retained and each chelating 1,3-diphenyl-1,3-propanedionato ligand is in a terminal position bonded to only one Ga atom, in more than 80% yield. The Ga-Ga bond is shortened [244.1(1) pm] compared to that in the starting compound tetraalkyldigallane(4) 1. The In-In bond of diindane(4) 2 is, however, cleaved in a similar reaction with dibenzoylmethane, and only the fragmentation product dialkyl(1,3-diphenyl-1,3-propanedionato)indium 10 could be isolated.
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  • 13
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 201-207 
    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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  • 14
    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.
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  • 15
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1661-1665 
    ISSN: 1434-1948
    Keywords: Gallium ; Low-valent compounds ; Macrocycles ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Tetrakis[bis(trimethylsilyl)methyl]digallane(4) 1 reacts with dicarboxylic acids like 1,4-benzenedi(methylcarboxylic) acid, 1,4-cyclohexanedicarboxylic acid, 1,6-hexanedicarboxylic acid, and 1,4-butanedicarboxylic acid (adipinic acid) by the release of two equivalents of bis(trimethylsilyl)methane and the retention of the Ga-Ga bond. Products are formed, in which the very short Ga-Ga bonds (237.7 pm on average) are bridged by two carboxylato groups. Two of these moieties are connected in each compound by two spacers (dimethylbenzene, cyclohexane, hexane, or butane) to form macrocyclic compounds with up to 22 atoms in the resultant heteroatomic rings. The dimeric form is also observed in solution. For comparison, the synthesis and structure of the product of the reaction of 1 with 1-adamantanecarboxylic acid is included, which also has the Ga-Ga bond (239.1 pm) bridged by two carboxylato groups.
    Additional Material: 3 Ill.
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  • 16
    ISSN: 0044-8249
    Keywords: Elektronenmangelverbindungen ; Hauptgruppenelemente ; Indium ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
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  • 17
    ISSN: 0044-8249
    Keywords: Cluster ; Hauptgruppenelemente ; Niedervalente Verbindungen ; Thallium ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
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  • 18
    ISSN: 0044-8249
    Keywords: Dialuminoxan ; Sterische Abschirmung ; π-Wechselwirkungen ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
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  • 19
    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.
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  • 20
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 621 (1995), S. 823-828 
    ISSN: 0044-2313
    Keywords: Al—Al bond ; insertion reaction with tert-butyl isocyanide ; trimeric cyano dialkyl alane ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Crystal Structure of the Trimeric [(Me3Si)2CH]2Al—CNTetrakis[bis(trimethylsilyl)methyl]dialane(4) 1 with an Al—Al bond reacts with tert-butyl isocyanide in the molar ratio of 1:2 within three days to give a mixture of several unknown products, from which the title compound 4 is isolated in a 26% yield by recrystallization from n-pentane. 4 is a trimer in the solid state via Al—C≡N—Al bridges showing a nine-membered Al3C3N3 heterocycle in a boat conformation. In contrary to the reaction with phenyl isocyanide the expected dark red product of the twofold insertion into the Al—Al bond under formation of a carbon-carbon single bond is detected only spectroscopically as a minor by-product.
    Notes: Tetrakis[bis(trimethylsilyl)methyl]dialan(4) 1 mit Al—Al-Bindung reagiert mit tert-Butylisocyanid im Molverhältnis 1:2 im Laufe von drei Tagen unter Bildung eines unübersichtlichen Produktgemisches, aus dem sich in 26% Ausbeute durch Umkristallisieren aus n-Pentan farblose Kristalle der Titelverbindung 4 isolieren lassen. Wie die Bestimmung der Kristallstruktur ergibt, liegt 4 im Festkörper als Trimeres mit Al—C≡N—Al-Brücken vor, und der sich ausbildende neungliedrige Al3C3N3-Heterozyklus weicht leicht von der Planarität unter Ausbildung einer Wannenkonformation ab. Das mit Phenylisontril hauptsächlich gebildete Produkt der zweifachen Insertion in die Al—Al-Bindung unter Knüpfung einer C—C-Einfachbindung wird hier nur in verunreinigter Form spektroskopisch nachgewiesen.
    Additional Material: 2 Ill.
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