ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Analytical Chemistry and Spectroscopy  (2)
  • 1
    ISSN: 0749-1581
    Keywords: 1H NMR ; 2H NMR ; Iron ; Porphyrin ; Isoporphyrin ; Tetraphenylporphyrin ; N-Phenyltetraphenylporphyrin ; Aryl Grignard reagents ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Addition of aryl Grignard reagents to an iron(III) tetraphenylporphyrin π cation radical, [(TPP⋅)FeIIICl] (SbCl6), in dichloromethane solution at 202 K yields a mixture of σ-phenyl iron(IV) tetraphenylporphyrin, [(TPP)FeIV(Ph)] (SbCl6), and σ-phenyl iron(III) tetraphenylporphyrin, (TPP)FeIIICl. A σ-phenyliron(III) complex is also formed by nucleophilic addition to the tetraphenylporphyrin macrocycle accompanied by σ-phenyl axial coordination. The complexes formed were identified by 1H NMR spectroscopy. A new route for generating σ-aryl iron(IV) porphyrin species from the iron(III) porphyrin π cation radical was established. The characteristic 1H NMR pattern of the low-spin iron(III) porphyrin ring modified species reflects its Cs symmetry and includes four upfield-shifted pyrrole resonances (2.31, -10.40, 20.39 and -20.87 ppm, 202 K) accompanied by a set of σ-phenyl resonances (ortho, -188.4; p-H, -102.5; p-CH3 for σ-p-tolyl, 162.3 ppm). Analysis of the paramagnetic shifts of the σ-phenyl (σ-p-tolyl) ligand of the new species indicates a high π spin density consistent with the electronic structure of low-spin iron(III) and the contribution of a σ-delocalization mechanism via donation from a filled σ-phenyl orbital to an empty dz2; orbital. The formation of a low-spin σ-phenyliron(III) isoporphyrin or low-spin σ-phenyl N-arylporphyrin is considered. The meso substitution can be accounted for by a mechanism which emphasizes the radical nature of the reaction substrate and involves the formation of σ-transient forms.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 30 (1992), S. 163-168 
    ISSN: 0749-1581
    Keywords: ESR ; Iminoxy radicals ; Diethyl phosphonate ; 31P hyperfine interaction ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Iminoxy radicals of a new type, having the general formula RC(=NO·)P(O)(OEt)2, were synthesized and characterized by means of ESR spectroscopy. The presence of two isomers due to the different position of the C=NO· fragment with respect to the R substituent and the P atom, and the relative stability of the isomers, was established. The influence of the R substituent on the relative population of the isomers was found. The nitrogen hyperfine constants for the isomers differ by about 10%, while the phosphorus hyperfine constant for the less populated isomer is about six time greater, reaching a value of 60 G. A linear correlation was found between the values of this hyperfine constant and Dimroth-Reichardt ET(30)solvent parameters. The solvent dependence of the 31P hyperfine constant was shown to be stronger than the dependence found for the 14N hyperfine constant of nitroxides and iminoxyls.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...