Repozytorium
Wyszukaj
Kolekcje
Inne
Monomeric and trimeric manganese(III) complexes of 2-hydroxy-5,10,15,20-tetraphenylporphyrin. Synthesis and characterization.
Autorzy
Rok wydania
1996
Czasopismo
Numer woluminu
35
Strony
4812-4818
DOI
10.1021/ic951663y
Kolekcja
Język
Angielski
Typ publikacji
Artykuł
The hydrolysis of the monomeric five-coordinate (2-BzO-TPP)MnIIICl complex has been investigated.1 Evidence for the formation of the cyclic trimeric complex [(2-O−TPP)MnIII]3 is presented. The 1H NMR spectroscopic evidence indicates that the trimeric manganese(III) complex has a head-to-tail cyclic trimeric structure with the pyrrolic alkoxide groups forming bridges from one macrocycle to the manganese(III) ion in the adjacent macrocycle PMn−O−PMn−O−PMn−O. The three manganese(III) porphyrin subunits are not equivalent. The characteristic upfield shift of the 3-H pyrrole resonance (−111.5 ppm at 291 K) was determined and considered as the diagnostic feature for the high-spin d4 manganese(III)−pyrrole alkoxide coordination. The strong upfield shift of the 3-H resonance has been accounted for by the donation of the electron density from the filled orbital of the 2-O atom on the half-occupied dz2 orbital of the external manganese(III) ion. The other pyrrole resonances produce the complex multiplet at the typical −5 to −40 ppm region. The 1H NMR spectra of the series of monomeric 2-substituted manganese(III) 5,10,15,20-tetraphenylporphyrin complexes (2-X-TPP)MnIIICl have been obtained and analyzed. The pattern of the assigned seven pyrrole resonances reflects the asymmetry imposed by 2-substitution and has been used as a 1H NMR spectroscopic probe to map the spin density distribution. The electronic effect is strongly localized at the β-substituted pyrrole. The upfield shift of the 3-H resonance increases in the order (2-NO2-TPP)MnIIICl < (2-BzO-TPP)MnIIICl < (2-OCH3-TPP)MnIIICl < (2-OH-TPP)MnIIICl < (2-NH2-TPP)MnIIICl < [(2-O-TPP)MnIII(OH)]- following the increasing electron-donating properties of the β-substituent
Słowa kluczowe
Pyrroles, Ions, Transition metals, Nuclear magnetic resonance spectroscopy, Resonance structures
Adres publiczny
https://doi.org/10.1021/ic951663y
Strona internetowa wydawcy
Podobne publikacje
H1 NMR investigations of triphenylporphyrin metal complexes and electronic interactions in iron(III) complexes of meso-meso-linked 5,5'-bis(10,15,20-triphenylporphyrin).
Wojaczyński Jacek, Latos-Grażyński Lechosław, Chmielewski Piotr J., Van Calcar P., Balch Alan L.
Iron complexes of C- and N-methylated 2-aza-21-carbaporphyrin: NMR studies.
Rachlewicz Krystyna, Gorzelańczyk Dominik, Latos-Grażyński Lechosław
Remarkable paramagnetically shifted 1H and 2H NMR spectra of iron(II) complexes of 2-aza-21carbaporphyrin: an evidence for agostic interaction.
Rachlewicz Krystyna, Wang S.-L., Peng C.-H., Hung Chen-Hsiung, Latos-Grażyński Lechosław