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  • 1
    Electronic Resource
    Electronic Resource
    Fixation of Carbon Dioxide by Oxalic Amidinato Magnesium Complexes: Structures and Reactions of Trimetallic Magnesium Carbamato and Related Complexes (2000)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 2000 (2000), S. 1055-1064 
    Details
    ISSN: 1434-1948
    Keywords: Carbon dioxide fixation ; Magnesium ; N ligands ; C-C coupling ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of oxalic amidines R1-N=C(NHR2)-C(NHR2)=N-R1 with CH3MgX followed by uptake of CO2 results in the formation of the trimeric carbamato complexes [R1-N=C(NR2-COO)-C(NR2COO)=N-R1]3Mg3(THF)6 (2a: R1 = R2 = Ph; 2b: R1 = R2 = p-tolyl) as the thermodynamically stable final products of the reaction. Their X-ray crystal structures show that the three metal centres are in a linear arrangement. The central magnesium ion is octahedrally surrounded by six O-donor atoms of the μ2-carbamato bridges, while both peripheral magnesium ions are facially coordinated by three O-donor atoms of the carbamato groups and three THF molecules. This coordination sphere can be considered as a structural model for the active centre in the ribulose-1,5-bisphosphate carboxylase/oxygenase enzyme. Compound 2a reacts with ZnCl2 or CoBr2, with CO2 elimination, to form dimeric complexes of the type [X2M(oxalamidinato)MX2][Mg(DMF)6] (M = Zn, Co; X = Cl, Br). X-ray crystal structure analyses show that the d-metals are tetrahedrally coordinated. The magnesium-bromide-containing intermediates in the formation of 2a and 2b are able to transfer CO2 to acetophenone, thus simulating the CO2 activation step in enzymatic biotin-dependent carboxylation reactions.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 2
    Electronic Resource
    Electronic Resource
    Synthesis, Structure and Reactions of the Homoleptic Alkyne Nickel(0) Complex (Alkyne)4Ni3 (Alkyne: 2-methyl-4-trimethylsilyl-3-butyn-2-ol)Dedicated to Professor Walter Siebert on the occasion of his 60th birthday. (1996)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 129 (1996), S. 1457-1461 
    Details
    ISSN: 0009-2940
    Keywords: Nickel(0) ; Alkyne complexes ; Hydrogen bonds ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Treatment of (cdt)Ni (cdt: cyclododeca-1,5,9-triene) with 2 equivalents of 2-methyl-4-trimethylsilyl-3-butyn-2-ol leads to the selective formation of the homoleptic complex (alkyne)4Ni3 (compound 3), which can be isolated in excellent yields. The solid-state structure of 3 exhibits three Ni centers, forming a bent Ni3 chain connected by two bridging alkynes. The other two alkynes are terminally coordinated. Additionally, the trimeric units are stabilized by three intramolecular hydrogen bonds. Two intermolecular hydrogen bonds connect the trimeric units to form a polymer rope. According to the 13C- and 1H-NMR spectra in THF the structure of the complex 3 in solution is very similar to that in the solid state. The reaction of 3 with some alkynediols and with 2,5,5-trimethylhex-3-yn-2-ol affords compounds of the type (alkyne)2Ni. Cot (cot: 1,3,5,7-cyclooctatetraene) converts 3 into [(cot)Ni]2, which in turn reacts with 2,5-dimethylhex-3-yne-2,5-diol to form the dimeric complex (alkyne)2Ni2(cot) 6. X-ray analysis of 6 reveals a very symmetrical structure in which cot connects both Ni(0) centers at opposite sides of the ring system.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19961291210
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  • 3
    Electronic Resource
    Electronic Resource
    Binukleare Nickel(0)-Alkin-Koordinationsverbindungen - Zusammenhang zwischen Ligandperipherie und supramolekularer StrukturProfessor Hans Georg von Schnering zum 65. Geburtstag gewidmet (1996)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 622 (1996), S. 1134-1144 
    Details
    ISSN: 0044-2313
    Keywords: Nickel(0) ; binuclear compounds ; functionalized alkynes ; supramolecular structures ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Binuclear Nickel(0) Alkyne Coordination Compounds - Correlation between Ligand Periphery and Supramolecular StructureReaction of Ni(cdt: 1,5,9-cyclododecatriene) with functionalized alkynes and subsequent reaction with ethylenediamines gives binuclear compounds of the type (diamine)Ni(μ-alkyne)Ni(alkyne). Compounds with alkyne-diols (N⁁N)Ni2(HOR1R2C—C≡C—CR1R2OH)2 show supramolecular structures in which two identical intramolecular and one intermolecular hydrogen bonds are realized. 1 and 2 (chelate ligand in each case N,N,N′,N′-tetramethylethylenediamine, TMEDA, in 1 R1 = R2 = Me, in 2 R1 = R2 = Et) polymer-like chains are built up by connecting the binuclear units. Via two intermolecular hydrogen bonds per organometallic unit in 1 and via one intermoleculare hydrogen bond in 2 the chains are connected to give double chains. By substitution of one methyl group of TMEDA by hydrogen (3: R1 = R2 = Me) a polymerlike network is produced by connecting the polymer-like chains.In compound 4 in which one of the methyl groups of TMEDA is substituted by CH2CH2NMe2 the polymer-like chains remain unconnected. In 5 (diamine = TMEDA, alkyne = (CH3)3C—C≡C—CMe2OH) one intermolecular hydrogen bond per organometallic unit is observed forming again polymer-like chains that are independent of each other.
    Notes: Durch Reaktion von Ni(cdt) (cdt: Cyclododeca-1,5,9-trien) mit funktionalisierten Alkinen und anschließender Umsetzung mit Ethylendiaminen erhält man binucleare Alkin-Nickel(0)-Verbindungen des Typs (diamin)Ni(μ-alkin)Ni(alkin). In Verbindungen mit Alkindiolen (N ⁁ N)Ni2(HOR1R2C—C≡C—CR1R2OH)2 werden supramolekulare Strukturen aufgebaut, die jeweils zwei gleichartige intramolekulare und eine intermolekulare Wasserstoffbrückenbindung aufweisen. In 1 und 2 (Chelatligand jeweils N,N,N′,N′-Tetramethylethylendiamin, TMEDA, in 1 R1 = R2 = Me, in 2 R1 = R2 = Et) bilden sich durch Verknüpfung der binuklearen Einheiten polymere Stränge, die in 1 durch zwei und in 2 durch eine Wasserstoffbrückenbindung pro Organometalleinheit zu Doppelsträngen verknüpft werden. Ersatz einer Methylgruppe in TMEDA durch Wasserstoff (3: R1 = R2 = Me) bewirkt, daß die polymeren Stränge zu einem polymeren Netzwerk verknüpft werden. In Verbindung 4 (R1 = R2 = Me), in der im TMEDA eine Methylgruppe durch CH2CH2NMe2 ersetzt ist, bleiben die zu 1-3 analogen polymeren Stränge untereinander unverknüpft.In 5 (Diamin = TMEDA, Alkin = (CH3)3C—C≡C—CMe2OH) wird pro Organometalleinheit eine intermolekulare Wasserstoffbrückenbindung gebildet, was ebenfalls zu voneinander unabhängigen polymeren Strängen führt.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19966220706
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