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  • (Arene)chromium complexes  (1)
  • Chelates  (1)
  • 1
    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.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 2
    Electronic Resource
    Electronic Resource
    Diastereoselective Ring Expansion Rearrangements of (Benzocyclobutenone)-and (Benzocyclobutenedione)chromium Complexes: Syntheses of Substituted 1-Indanone and 1,3-Indandione Complexes (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 823-835 
    Details
    ISSN: 1434-193X
    Keywords: (Arene)chromium complexes ; α-Ketol rearrangement ; Vinylcyclobutene-cyclohexadiene rearrangement ; Benzocyclobutenes ; Indanone derivatives ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -Organolithium and Grignard reagents add to the oxo group of (benzocyclobutenone)tricarbonylchromium(0) (1) diastereoselectively from the exo face of the organic ligand. If acyl anion equivalents are used as nucleophiles, deprotection of the carbonyl functions of the adducts causes ring expansion reactions to occur. Among these a rare example of an anion-accelerated 1-vinylcyclobutenol-cyclohexadienol rearrangement is reported which results, after isomerization, in a naphthol complex. Other ring expansion reactions gave coordinated substituted indanone derivatives. The facial differentiation by the tricarbonylchromium moiety allows for the first time the determination of the distereoselectivity of these reactions. The 1-oxoindan-2-ol derivatives obtained can undergo an α-ketol rearrangement with formation of the corresponding 2-oxoindan-1-ol complexes. Some of these reactions were performed with nonracemic starting material in order to determine how far chirality transfer from the planar chiral starting material to C-2 in the indanone system was possible. The ring expansion was also feasible with the benzocyclobutenedione complex as a starting compound, the reaction giving substituted 1,3-indandione complexes. Crystal structure analyses of three of the complexes prepared are reported.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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