Spectroscopy of cobalt–ethylenediamine–oxygen adducts in the supercages of zeolites
- 1 January 1981
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in J. Chem. Soc., Dalton Trans.
- No. 4,p. 914-922
- https://doi.org/10.1039/dt9810000914
Abstract
The complex [Co(en)3]2+(en = ethylenediamine) can be synthesized in the supercages of faujasite-type zeolites by adsorption of gaseous en. On dehydrated cobalt–zeolites additional heating is necessary to enhance the mobility of Co2+ from the small cages to the supercages. Upon heating, [Co(en)3]2+ decomposes to [Co(en)2]2+ and to [Co(en)]2+. The mono and tris complexes are not capable of binding O2 whereas the bis complex forms the 1 : 1 superoxo-complex [Co(en)2(O2)]2+ and the 2 : 1 monobridged peroxo-complex [{Co(en)2}2(O2)]4+ with O2. The former is preferentially formed when not more than one cobalt atom is in each supercage, the latter when more than one cobalt, statistically, is in each supercage. The 1 : 1 superoxo-complex is unstable, and its formation is only partially reversible. The amount of electron transfer from cobalt to O2 is estimated to be 0.46 e, indicating a weak σ-donor ligand trans to O2 – in the complex. When [Co(en)3]2+ and physisorbed en are present in the supercages the interaction with O2 is complex and involves oxidation of en with formation of water.Keywords
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