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Influence of the nature of ligands in iridium complexes with C 60 fullerene and · P(O)(OPr i ) 2 , · CMe 3 , and · CCl 3 radicals on regioselectivity of addition and stability of spin-adducts formed: an EPR study

Gasanov, R. ; Tsikalova, M. ; Martynova, E. ; Chistyakov, A. ; Stankevich, I. ; Novikov, Yu.

Russian Chemical Bulletin, 2007, Vol.56(7), pp.1351-1358 [Periódico revisado por pares]

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  • Título:
    Influence of the nature of ligands in iridium complexes with C 60 fullerene and · P(O)(OPr i ) 2 , · CMe 3 , and · CCl 3 radicals on regioselectivity of addition and stability of spin-adducts formed: an EPR study
  • Autor: Gasanov, R. ; Tsikalova, M. ; Martynova, E. ; Chistyakov, A. ; Stankevich, I. ; Novikov, Yu.
  • Assuntos: metallofullerenes ; EPR spectroscopy ; steric and electronic effects ; phosphoryl, -butyl, and trichloromethyl radicals ; regioselectivity ; rate constants for addition
  • É parte de: Russian Chemical Bulletin, 2007, Vol.56(7), pp.1351-1358
  • Descrição: The addition of · P(O)(OPr i ) 2 (R 1 ), · CMe 3 (R 2 ), and · CCl 3 (R 3 ) radicals to metallofullerenes (η 2 -C 60 )IrH(CO)(CNBu t ) 2 ( o -HCB 10 H 9 CCH 2 PPh 2 -B,P) ( 1 ), (η 2 -C 60 )IrH(CO)(DIOP) (DIOP is (4 R ,5 R )-(+)-4,5-bis(diphenylphosphinomethyl)-2,2-dimethyl-1,3-dioxolane, 2 ), and (η 2 -C 60 )IrH(CO)(PPh 3 ) 2 ( 3 ) was studied by EPR spectroscopy. A stability study of spin adducts (SAs) of R 1 radicals with complexes 1 and 2 showed that when the reactions are initiated by illumination with 366-nm light, the EPR spectra exhibit only signals of those isomers that are formed upon attack of the R 1 radicals on the carbon atoms of the cis-1 and cis-2 bonds ( i.e. , carbon atoms of the fullerene hemisphere to which the metallofragment is attached). Investigations of the reactions of R 2 and R 3 radicals with complexes 1–3 initiated with 366-nm light made it possible to detect (i) regioisomers formed by adding these radicals to carbon atoms of the cis-n bonds and (ii) SAs formed by adding the radicals to carbon atoms of other bonds in complexes 1–3 . The hyperfine structure of the EPR spectrum essentially depends on the spatial structure of substituents at the metal atom and allows individual regioisomers of not only phosphoryl radicals, but also carbon-centered radicals R 2 and R 3 with metallofullerenes 1–3 to be identified. The rate constants for addition of R 2 and R 3 radicals to complexes 2 and 3 were determined.
  • Idioma: Inglês

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