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On the Oxidation of Gallium and Indium: Characterization of the Cyclic and Linear GaO 2 and InO 2 Molecules Generated by the Spontaneous and Photoinduced Reaction of Ga and In Atoms with O 2 and Determination of the Reaction Mechanism
Author(s) -
Köhn Andreas,
Gaertner Benjamin,
Himmel HansJörg
Publication year - 2005
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200500137
Subject(s) - chemistry , isomerization , molecule , matrix isolation , gallium , raman spectroscopy , bond length , atom (system on chip) , indium , linear molecular geometry , isotopomers , biochemistry , physics , organic chemistry , computer science , optics , embedded system , catalysis
In this work, the spontaneous and photolytically activated reactions of Ga and In atoms (M) with O 2 (in Ar and solid O 2 ) are studied with the aid of the matrix‐isolation technique and the use of IR, Raman, and UV/Vis spectroscopy in combination with detailed quantum‐chemical calculations. Vibrational spectra were recorded for several different isotopomers ( 69 Ga, 71 Ga, 16 O 2 , 18 O 2 , 16 O 18 O). The results show that the spontaneously formed cyclic MO 2 molecules photoisomerize to give the linear OMO molecules. The collected vibrational data were then used to characterize the bond properties of the linear OMO molecules in detail. The results are compared to those obtained for CO 2 + and neutral OEO compounds, where E is an element of Group 14. Quantum‐chemical calculations were carried out at various levels of theory for GaO 2 . These calculations indicate that linear OMO is slightly more stable than its cyclic isomer. These calculations were also used to obtain information about the reaction mechanism, and show that the formation of the cyclic isomer from Ga atoms and O 2 occurs without a significant barrier. Abrupt changes of the dipole moment and the OO bond length during the approach of the O 2 molecule toward the Ga atom mark the point on the potential energy surface at which one electron jumps from the Ga atom onto the O 2 unit. The isomerization of cyclic GaO 2 to the linear global minimum structure is accompanied by a significant barrier, which explains why this reaction requires photoactivation.