Structural and EPR Studies of Pyrophosphate-Bridged Dinuclear CuII Complexes
Two new pyrophosphate-bridged copperII complexes, [Cu(dpa)(H2O7P2)]21 and [Cu2(terpy)2(HO7P2)·(H2O4P)·(H3O4P)·(H2O)] 2 (dpa = 2,2′-dipyridylamine and terpy = 2,2′:6′,2″-terpyridine) were isolated and their crystal structures determined by single-crystal X-ray diffraction. The compounds are triclinic...
| Autores: | , , , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2014 |
| País: | Argentina |
| Institución: | Consejo Nacional de Investigaciones Científicas y Técnicas |
| Repositorio: | CONICET Digital (CONICET) |
| Idioma: | inglés |
| OAI Identifier: | oai:ri.conicet.gov.ar:11336/4401 |
| Acceso en línea: | http://hdl.handle.net/11336/4401 |
| Access Level: | acceso abierto |
| Palabra clave: | Copper Pyrophosphates Structure Magnetic Interactions Epr https://purl.org/becyt/ford/1.4 https://purl.org/becyt/ford/1 |
| Sumario: | Two new pyrophosphate-bridged copperII complexes, [Cu(dpa)(H2O7P2)]21 and [Cu2(terpy)2(HO7P2)·(H2O4P)·(H3O4P)·(H2O)] 2 (dpa = 2,2′-dipyridylamine and terpy = 2,2′:6′,2″-terpyridine) were isolated and their crystal structures determined by single-crystal X-ray diffraction. The compounds are triclinic and contain dinuclear copperII units bridged by pyrophosphate anions. The EPR spectra observed in three planes of single crystal samples as a function of field orientation at 293 K for compounds 1 and 2, and also for two other pyrophosphate compounds already reported, [Cu(bipy)(cis-H2O7P2)]2·3(H2O) 3 and [Cu(bipy)(trans-H2P2O7)]24 display a single resonance for any field orientation and temperatures T between 4 and 293 K, as in mononuclear spin systems, without hyperfine structure, and their g-factors and line widths were measured. The relations between the principal directions of the g-matrices and the molecular structures are discussed and compared with related compounds. The temperature dependences of the intensity of the EPR signals observed for 1–4 above 4 K indicate a paramagnetic Curie behavior, with no indication of intradinuclear exchange interactions (so, |J| < 2 K). The absence of dinuclear splitting and of hyperfine structure of the dinuclear units is explained in terms of averaging out by the interdinuclear interactions, allowing to set a lower limit of their magnitudes. |
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