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  • 1
    Electronic Resource
    Electronic Resource
    1,2-Azaborolyl-Komplexe, XXIX. Synthese und Eigenschaften von 1,2-Azaborolylboranen (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 73-80 
    Details
    ISSN: 0009-2940
    Keywords: 1,2-Azaborolylboranes ; Iron complexes ; Sandwich complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1,2-Azaborolyl Complexes, XXIX[1].  -  Synthesis and Properties of 1,2-AzaborolylboranesThe Li salts of variously substituted 1,2-azaboroles 1a-1c react with numerous halogenoboranes to give the corresponding mono(1,2-azaborol-3-yl)boranes 2-12. In the case of 11, which is substituted by SiMe3 at C-3, 2,5-dihydro isomers can be observed as intermediates by NMR spectroscopy with a B(Cl)NMe2 group at C-5 and the SiMe3 substituent either at C-4 (11a) or at C-3 (11b). The thermodynamically stable final product 11 is probably formed from 11b via an allylic transition state. The X-ray structure analysis of 11 at ca. 0°C proves the suggested structure. The first and only example of a bis(1,2-azaborol-3-yl)borane 13 was realized by the reaction of (1-tert-butyl-2,3-dihydro-2-methyl-1H-1,2-azaborol-3-yl)-chloro(dimethylamino)borane (3) with 1-tert-butyl-2-methyl-1,2-azaborolyllithium (1a). The X-ray structure analysis of bis(1-tert-butyl-2,3-dihydro-2-methyl-1H-1,2-azaborol-3-yl)-(dimethylamino)borane (13) shows one of the two NMR-spectroscopically observed diastereoisomers with perpendicularly oriented azaborolyl rings. Two iron sandwich complexes were synthesized; 15 is formed via 1-tert-butyl-3-[bis(dimethylamino)boryl]-2-methyl-1,2-azaborolyllithium (14) and FeCl2, whereas the ClB-substituted sandwich complex 16 results from the reaction of 15 with BCl3.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270111
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  • 2
    Electronic Resource
    Electronic Resource
    Synthesis, Structure, Electrochemistry and Reactivity of the Bis(μ-σ-stannanediyl)dinickel Butterfly Cluster [{{(SiMe3)2CH}2Sn-Ni(η5-Cp)}2](Ni2-Sn2) (1999)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 1987-1993 
    Details
    ISSN: 1434-1948
    Keywords: Cluster ; Nickel ; Tin ; Bimetallic complexes ; Electrochemistry ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Addition of stannylene [{(SiMe3)2CH}2Sn:] (2) to the unbridged homobimetallic Ni-Ni bond of [{PEt3Ni(η5-Cp)}2] (1) gives the heterobimetallic, tetranuclear compound [{{(SiMe3)2CH}2Sn-Ni(η5-Cp)}2] (3) with a butterfly arrangement and leaves the Ni-Ni bond of 1 intact. Elimination of both PEt3 ligands from the starting material 1 is observed, probably due to steric restraints. Compound 3 is formally related to the hypothetical closo-borane B4H42-. The Ni-Ni bond in 3 is only slightly elongated [2.454(3) Å] when compared to the starting material 1 [2.41(1) Å]. Compound 3 displays a butterfly arrangement with a hinge angle of 62.5°. An alternative route to 3 is by a direct reaction between nickelocene (5) and Lappert's stannylene [{(SiMe3)2CH}2Sn:] in 63% yield. Treating 3 with water results in the cleavage of an Ni-Sn bond and subsequent opening of the cluster cage of 3 to form the trinuclear compound [(η5-Cp)Ni{Sn(CH(SiMe3)2}2OH] (6) having an Sn-OH-Sn bridge. The hydroxy proton in 6 can be exchanged by deuterium within a few minutes, as determined by 1H-NMR spectroscopy, giving the monodeuterio product, [D1]-6. Compound 6 is reactive towards acetonitrile, leading to cleavage of one Ni-Sn bond, elimination of one [{(SiMe3)2CH}2Sn:] unit, and formation of the organotin hydroxo complex [{(SiMe3)2CH}2(OH)Sn-Ni(η5-Cp)(CH3CN)] (7). In this complex, acetonitrile is coordinated to Ni via its σ lone pair, bearing the OH ligand in a terminal bonding mode to tin.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Synthesis and Structure of 2-Hydro-, 2-Alkyl-, 2-Alkynyl-, and 2-Stannyl-2,3-dihydro-1H-1,3,2-diazaboroles (1999)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 491-497 
    Details
    ISSN: 1434-1948
    Keywords: Boron ; Diazaboroles ; Hydrides ; Tin ; Heterocycles ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1,3-Di-tert-butyl-2,3-dihydro-1H-1,3,2-diazaborole (4a) and 1,3-bis(2,6-dimethylphenyl)-2,3-dihydro-1H-1,3,2-diazaborole (4b) were formed by the reaction of the corresponding 2-bromo or 2-iodo derivatives 1a and 2b with LiAlH4. Treatment of 1a with n-butyllithium afforded 2-n-butyl-1,3-di-tert-butyl-2,3-dihydro-1H-1,3,2-diazaborole (5a), whereas 1,3-di-tert-butyl-2-cyano-2,3-dihydro-1H-1,3,2-diazaborole (3a) was converted into the 2-tert-butyl derivative 6a or the 2-ethynyl-1,3,2-diazaborole 7a by means of tert-butyllithium or by the ethylenediamine adduct of lithium acetylide. Similarly, 1,3-di-tert-butyl-2-trimethylstannyl-2,3-dihydro-1H-1,3,2-diazaborole (8a) and 1,3-bis(2,6-dimethylphenyl)-2-trimethylstannyl-2,3-dihydro-1H-1,3,2-diazaborole (8b) were accessible from 1a or 2b and trimethylstannyllithium. In the complex 9a the compound 3a serves as an η1 ligand towards the [Cr(CO)5] unit via the cyano group. These novel compounds were characterized by 1H-, 11B-, 13C-, and 119Sn-NMR spectroscopy, as well as by X-ray structure analyses of 4b, 8a, and 9a.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Stoichiometric Homo-Aldol Coupling of Acetone, Cyclohexanone, and Acetophenone by the [(η5-CpR)Co] (R = Me5, 1,2,4-tri-tert-butyl) Moiety (2000)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 2000 (2000), S. 713-718 
    Details
    ISSN: 1434-1948
    Keywords: Cobalt ; Sandwich complexes ; Aldol reactions ; Ketones ; C-H activation ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Acetone, cyclohexanone, and acetophenone react with the toluene-bridged triple-decker complexes [{(η5-CpR)Co}2-μ-(η4:η4-toluene)] (R = Me5 3; 1,2,4-tri-tert-butyl 4) by toluene substitution and homo-aldol coupling of two ketone molecules to form the first oxadiene cobalt complexes. These reactions may involve a Csp3-H activation step of the ketones by 14 e- [(η5-CpR)Co] fragments generated from the triple-decker complexes 3 and 4. If no acidic protons are present in the position α to the carbonyl carbon position in the ketone, no Csp3-H activation occurs. In agreement with this, benzophenone does not react with complex 3.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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