Highly efficient electron-transfer processes over thermally activated alkaline earth oxides. Monolayer anion radical formation with nitrobenzene--MgO and high concentrations of CO radicals over MgO, CaO, SrO, BaO, and ThO/sub 2/

Journal Article · Fri Sep 01 00:00:00 EDT 1978 · Inorg. Chem.; (United States)

DOI:https://doi.org/10.1021/ic50187a064· OSTI ID:6896930

Klabunde, K J; Kaba, R A; Morris, R

Authors have attempted to determine quantitatively whether electron-transfer processes are of major importance on the surface of alkaline earth oxides and what types of sites are involved. Purified, powdered magnesium oxide was heat treated in vacuo overnight at 600/sup 0/C. Total MgO/surface MgO molecules ratio was determined to be 9.4. Sample was treated with nitrobenzene. Color change from white to brown; radical formation was allowed to proceed for about 1 week. Spectra recorded during this period showed that maximum radical concentration was reached in 1 to 2 days at 25/sup 0/C. Spin counts indicated that 20 to 25 surface molecules are necessary for the formation of the anion radical. Electron-transfer process appears to be extremenly important on the surface even in a stoichiometric sense. Essentially, a monolayer of nitrobenzyl radical is formed on the surface of the MgO. Carbon monoxide studies were conducted. Maximum radical production was attained in 30 to 60 days. Evidence showed that the CO radical formation was much more selective process than the nitrobenzyl formation. Ca 15% of the CO adsorbed eventually formed radical species. The authors believe that the radical forming processes are not due to artifacts or to impurities, which could not possibly account for the number of radical species formed. They have concluded that coordination defects on the MgO surface are responsible for the reactivity. Further studies with other alkaline earth oxides are being conducted.

• Research Organization: Univ. of North Dakota, Grand Forks
• OSTI ID: 6896930
• Journal Information: Inorg. Chem.; (United States), Vol. 17:9
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
CARBON MONOXIDE
CHEMICAL REACTIONS
MAGNESIUM OXIDES
NITROBENZENE
CHEMICAL REACTION YIELD
COMPARATIVE EVALUATIONS
CRYSTAL DEFECTS
ELECTRON TRANSFER
HEAT TREATMENTS
RADICALS
STOICHIOMETRY
SURFACE AREA
TIME DEPENDENCE
ALKALINE EARTH METAL COMPOUNDS
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
CRYSTAL STRUCTURE
MAGNESIUM COMPOUNDS
NITRO COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
SURFACE PROPERTIES
YIELDS
400201* - Chemical & Physicochemical Properties