5.14.2 Interaction with Oxygen
Co.ϒAl 2 O 3 was contacted with O 2 at room temperature for 5 min. The X band ESR
spectrum of the sample is reported in Fig. 5.12, line e.
The resonance lines in (e) g ‖ = 2.034 and g † = 2.00 indicate the presence of the
Al
3+ -O 2
− species.
Rh ϒAl 2 O 3 treated by O 2 shows asymmetric resonance lines, g 1 = 2.09,
g 2 = 2.03, g 3 = 2.00; these suggest that the unpaired electron occupies a O 2 p*
orbital with a small contribution of a d p Rh orbital (line c).
Rh ZrO 2 reveals the presence of the same species as on Rh ϒAl 2 O 3 together
with the species Zr
4+ -O 2
− .
Co ZrO 2 did not show resonances.
(a)
(b)
(c)
Fig. 5.11 X band ESR
spectra of a ϒAl 2 O 3 and
b Rh.ϒAl 2 O 3 from pyrolysis
of [Rh 4 (CO) 12 ] ϒAl 2 O 3 at
150 °C, c Rh.ϒAl 2 O 3 from
pyrolysis of [Rh 4 (CO) 12 ]
ϒAl 2 O 3 at 250 °C [12]
5.14 Discussion of the Case
99
Co.ϒAl 2 O 3 was contacted with O 2 at room temperature for 5 min. The X band ESR
spectrum of the sample is reported in Fig. 5.12, line e.
The resonance lines in (e) g ‖ = 2.034 and g † = 2.00 indicate the presence of the
Al
3+ -O 2
− species.
Rh ϒAl 2 O 3 treated by O 2 shows asymmetric resonance lines, g 1 = 2.09,
g 2 = 2.03, g 3 = 2.00; these suggest that the unpaired electron occupies a O 2 p*
orbital with a small contribution of a d p Rh orbital (line c).
Rh ZrO 2 reveals the presence of the same species as on Rh ϒAl 2 O 3 together
with the species Zr
4+ -O 2
− .
Co ZrO 2 did not show resonances.
(a)
(b)
(c)
Fig. 5.11 X band ESR
spectra of a ϒAl 2 O 3 and
b Rh.ϒAl 2 O 3 from pyrolysis
of [Rh 4 (CO) 12 ] ϒAl 2 O 3 at
150 °C, c Rh.ϒAl 2 O 3 from
pyrolysis of [Rh 4 (CO) 12 ]
ϒAl 2 O 3 at 250 °C [12]
5.14 Discussion of the Case
99