Photomagnetic Switching of Heterometallic Complexes [M(dmf)[subscript 4](H[subscript 2]O)[subscript 3]([mu]-CN)Fe(CN)[subscript 5]]H[subscript 2]O (M=Nd, La, Gd, Y) Analyzed by Single-Crystal X-ray Diffraction and Ab Initio Theory
- Aarhus
Single-crystal X-ray diffraction measurements have been carried out on [Nd(dmf){sub 4}(H{sub 2}O){sub 3}({mu}-CN)Fe(CN){sub 5}]{center_dot}H{sub 2}O (1; dmf=dimethylformamide), [Nd(dmf){sub 4}(H{sub 2}O){sub 3}({mu}-CN)Co(CN){sub 5}]{center_dot}H{sub 2}O (2), [La(dmf){sub 4}(H{sub 2}O){sub 3}({mu}-CN)Fe(CN){sub 5}]{center_dot}H{sub 2}O (3), [Gd(dmf){sub 4}(H{sub 2}O){sub 3}({mu}-CN)Fe(CN){sub 5}]{center_dot}H{sub 2}O (4), and [Y(dmf){sub 4}(H{sub 2}O){sub 3}({mu}-CN)Fe(CN){sub 5}]{center_dot}H{sub 2}O (5), at 15(2) K with and without UV illumination of the crystals. Significant changes in unit-cell parameters were observed for all the iron-containing complexes, whereas 2 showed no response to UV illumination. Photoexcited crystal structures have been determined for 1, 3, and 4 based on refinements of two-conformer models, and excited-state occupancies of 78.6(1), 84(6), and 86.6(7) % were reached, respectively. Significant bond-length changes were observed for the Fe-ligand bonds (up to 0.19 {angstrom}), the cyano bonds (up to 0.09{angstrom}), and the lanthanide-ligand bonds (up to 0.10{angstrom}). Ab initio theoretical calculations were carried out for the experimental ground-state geometry of 1 to understand the electronic structure changes upon UV illumination. The calculations suggest that UV illumination gives a charge transfer from the cyano groups on the iron atom to the lanthanide ion moiety, {l_brace}Nd(dmf){sub 4}(H{sub 2}O){sub 3}{r_brace}, with a distance of approximately 6 {angstrom} from the iron atom. The charge transfer is accompanied by a reorganization of the spin state on the {l_brace}Fe(CN)6{r_brace} complex, and a change in geometry that produces a metastable charge-transfer state with an increased number of unpaired electrons, thus accounting for the observed photomagnetic effect.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 1002569
- Journal Information:
- Chem.-Eur. J., Vol. 16, Issue (24) ; 06, 2010; ISSN 0947-6539
- Country of Publication:
- United States
- Language:
- ENGLISH
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