| Autor: |
Balatskiy DV; Institute of Chemistry, Far Eastern Branch of the Russian Academy of Sciences, 159 100-letiya Vladivostoka pr., 690022 Vladivostok, Russia., Chuprin AS; Nesmeyanov Institute of Organoelement Compounds of the Russian Academy of Sciences, 28-1 Vavilova st., 119334 Moscow, Russia. voloshin@ineos.ac.ru.; Kurnakov Institute of General and Inorganic Chemistry of the Russian Academy of Sciences, 31 Leninsky pr., 119991 Moscow, Russia., Dudkin SV; Nesmeyanov Institute of Organoelement Compounds of the Russian Academy of Sciences, 28-1 Vavilova st., 119334 Moscow, Russia. voloshin@ineos.ac.ru.; Kurnakov Institute of General and Inorganic Chemistry of the Russian Academy of Sciences, 31 Leninsky pr., 119991 Moscow, Russia., Desdin-Garcia LF; Centro de Aplicaciones Tecnológicas y Desarrollo Nuclear, No. 502, Calle 30 y 5ta Ave. Miramar, CP 11300 La Habana, Cuba., Corcho-Valdes AL; Centro de Aplicaciones Tecnológicas y Desarrollo Nuclear, No. 502, Calle 30 y 5ta Ave. Miramar, CP 11300 La Habana, Cuba., Antuch M; Centro de Aplicaciones Tecnológicas y Desarrollo Nuclear, No. 502, Calle 30 y 5ta Ave. Miramar, CP 11300 La Habana, Cuba., Buznik VM; Institute of Chemistry, Far Eastern Branch of the Russian Academy of Sciences, 159 100-letiya Vladivostoka pr., 690022 Vladivostok, Russia.; Kurnakov Institute of General and Inorganic Chemistry of the Russian Academy of Sciences, 31 Leninsky pr., 119991 Moscow, Russia., Bratskaya SY; Institute of Chemistry, Far Eastern Branch of the Russian Academy of Sciences, 159 100-letiya Vladivostoka pr., 690022 Vladivostok, Russia., Voloshin YZ; Nesmeyanov Institute of Organoelement Compounds of the Russian Academy of Sciences, 28-1 Vavilova st., 119334 Moscow, Russia. voloshin@ineos.ac.ru.; Kurnakov Institute of General and Inorganic Chemistry of the Russian Academy of Sciences, 31 Leninsky pr., 119991 Moscow, Russia. |
| Abstrakt: |
Combined experimental 57 Fe Mössbauer and theoretical DFT study of a series of iron(II)-centered (pseudo)macrobicyclic analogs and homologs was performed. The field strength of the corresponding (pseudo)encapsulating ligand was found to affect both the spin state of a caged iron(II) ion and the electron density at its nucleus. In a row of the iron(II) tris-dioximates, passing from the non-macrocyclic complex to its monocapped pseudomacrobicyclic analog caused an increase both in the ligand field strength and in the electron density at the Fe 2+ ion, and, therefore, a decrease in the isomer shift (IS) value (so-called "semiclathrochelate effect"). Its macrobicyclization, giving the quasiaromatic cage complex, caused a further increase in the two former parameters and a decrease in IS (so-called "macrobicyclic effect"). The trend of their IS values was successfully predicted using the performed quantum-chemical calculations and the corresponding linear correlation with the electron density at their 57 Fe nuclei was plotted. A variety of different functionals can be successfully used for such excellent prediction. The slope of this correlation was found to be unaffected by the used functional. In contrast, the predictions of both the sign and the values of quadrupole splitting (QS) for them, based on the theoretical calculations of EFG tensors, were found to be a real great challenge, which could not be solved at the moment even in the case of these C 3 -pseudosymmetric iron(II) complexes with known XRD structures. The latter experimental data allowed us to deduce a sign of the QSs for them. The straightforwarded molecular design of a (pseudo)encapsulating ligand is proposed to control both the spin state and the redox characteristics of an encapsulated metal ion. |
