Wydział Chemii

Piotr J. Chmielewski

Lechosław Latos-Grażyński

1997

Inorganic Chemistry

36

840-845

10.1021/ic9608760

Naukowa

Angielski

Artykuł

One-electron oxidation of nickel(II) 5,10,15,20-tetraaryl-2-aza-21-carbaporphyrin ((CTPP)Ni^II) and nickel(II) 2-methyl-5,10,15,20-tetraaryl-2-aza-21-carbaporphyrin ((MeCTPP)Ni^II) resulted in formation of rare organonickel(III) derivatives. The half-wave potential for the first oxidation of (CTPP)Ni^II and (MeCTPP)Ni^II equals 0.66 V and 0.72 V, respectively (vs SCE, CH₂Cl₂ solution, TBAP). The EPR spectral patterns of the one-electron-oxidized species have been determined at 293 and 77 K. In both temperatures the spectral parameters markedly depend on the axial ligand introduced by oxidants or in methathesis. In each case the spin-Hamiltonian parameters (g_av > 2.1 (77 K) or g_iso > 2.1 (293 K)) reveal a metal-centered oxidation rather than a cation radical formation (g_iso ≈ 2.002). The localization of the one-electron oxidation on the nickel ion has been supported by the observation of ⁶¹Ni hyperfine splitting. The ²H NMR investigations, carried out for pyrrole deuterated derivatives:  (CTPP-d₇)Ni^IIIBr, (CTPP-d₇)Ni^III(NO₃), and (Me-d₃-CTPP)Ni^IIIOH, confirmed independently by the nickel(III) electronic structure.

Electron paramagnetic resonance spectroscopy, Ligands, Macrocycles, Oxidation, Pyrroles

https://doi.org/10.1021/ic9608760

https://www.acs.org/content/acs/en.html