The system phthalocyaninatocobalt(II)·Al2O3, ([Co(pc)]·γ-Al2O3), if contacted with air at high temperatures (70 - 150 °C), has been found to be active to oxygen chemisorption. ESR measurements revealed that the chemisorption is a reversible process, leading to the formation of [Co(pc)O2]·γ-Al2O3 as a paramagnetic intermediate. ESR spectroscopy has also been used to investigate the rate of angular reorientation of O2 absorbed on the [Co(pc)]·γ-Al2O3 surface at a variety of temperatures. Computer simulations of the ESR spectra were compared with spectra obtained experimentally, and correlation times for reorientation and anisotropic g values were calculated. The fitting of the anisotropic g values to a model based on second-order perturbation theory suggests that the ground state of [Co(pc)O2]·γ-Al2O3 is (x2 - y2)2(z2)2(xz or yz)2(yz or xz), with the unpaired electron localized mainly on cobalt. According to this finding, oxygen interacts with cobalt mainly through a π overlap. © 1982.
Barzaghi, M., Beringhelli, T., Morazzoni, F. (1982). OXYGEN-CHEMISORPTION ON GAMMA-AL2O3.PHTHALOCYANINATO-COBALT(II) - COORDINATION OF O-2 BY COMPLEXED COBALT CENTERS - TUMBLING OF MOLECULAR-OXYGEN ON SURFACE COBALT CENTERS. JOURNAL OF MOLECULAR CATALYSIS, 14(3), 357-374 [10.1016/0304-5102(82)80096-5].
OXYGEN-CHEMISORPTION ON GAMMA-AL2O3.PHTHALOCYANINATO-COBALT(II) - COORDINATION OF O-2 BY COMPLEXED COBALT CENTERS - TUMBLING OF MOLECULAR-OXYGEN ON SURFACE COBALT CENTERS
MORAZZONI, FRANCA
1982
Abstract
The system phthalocyaninatocobalt(II)·Al2O3, ([Co(pc)]·γ-Al2O3), if contacted with air at high temperatures (70 - 150 °C), has been found to be active to oxygen chemisorption. ESR measurements revealed that the chemisorption is a reversible process, leading to the formation of [Co(pc)O2]·γ-Al2O3 as a paramagnetic intermediate. ESR spectroscopy has also been used to investigate the rate of angular reorientation of O2 absorbed on the [Co(pc)]·γ-Al2O3 surface at a variety of temperatures. Computer simulations of the ESR spectra were compared with spectra obtained experimentally, and correlation times for reorientation and anisotropic g values were calculated. The fitting of the anisotropic g values to a model based on second-order perturbation theory suggests that the ground state of [Co(pc)O2]·γ-Al2O3 is (x2 - y2)2(z2)2(xz or yz)2(yz or xz), with the unpaired electron localized mainly on cobalt. According to this finding, oxygen interacts with cobalt mainly through a π overlap. © 1982.
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