Unique Coordination of Copper in Hexacyanometallates
Within divalent transition metals hexacyanometallates (III) the copper (2+) salts show unique features. To the copper (2+) salts correspond the shortest unit cell edges, the highest (CN) vibration frequencies, the lowest hydration degree and dehydration temperatures, the lowest Mössbauer isomer shif...
| Autores: | , , , , , |
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| Formato: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2006 |
| País: | México |
| Recursos: | Instituto Politécnico Nacional |
| Repositorio: | Repositorio Digital del IPN |
| OAI Identifier: | oai:www.repositoriodigital.ipn.mx:123456789/11230 |
| Acesso em linha: | http://hdl.handle.net/123456789/742 http://www.repositoriodigital.ipn.mx/handle/123456789/11230 |
| Access Level: | acceso abierto |
| Palavra-chave: | Molecular Magnet Mössbauer Prussian Blue Analogues Bonding Properties Porous Material |
| Resumo: | Within divalent transition metals hexacyanometallates (III) the copper (2+) salts show unique features. To the copper (2+) salts correspond the shortest unit cell edges, the highest (CN) vibration frequencies, the lowest hydration degree and dehydration temperatures, the lowest Mössbauer isomer shift value, and the strongest magnetic exchange interaction (J) between the metal centers. Such unique features were attributed to a particularly strong bond of the copper atom to the N ends of the CN groups. The driving force for such behaviour was ascribed to a combined effect where the copper (2+) shows a high ability to receive electrons in its 3d hole favouring an electronic configuration close to 3d10 and the CN group complements such ability donating electrons through its 5 orbital which has certain anti-bonding character. This hypothesis is supported by the obtained structural and spectroscopic data. The occurrence of a cooperative Jahn–Teller effect in this family of materials was discarded. In the pseudo-octahedral coordination for the copper (2+) atom the eg orbital degeneration is initially removed. The collected EPR spectra are characteristic of a cubic environment (isotropic g-values). Analogue evidence was obtained from high resolution X-ray powder patterns recorded in the 12–300 K temperature range. All the patterns correspond to a cubic unit cell. |
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