Inorganic Chemistry
Article
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frequency range (10−1000 Hz) available in the more sensitive
SQUID susceptometer (Figure 7). Maxima are barely visible
only at the lowest temperatures explored, but a behavior well
comparable with that of the pristine compound can be
unambiguously observed. In spite of the higher signal-to-
noise ratio, data treatment using the Debye model (eq 3)
afforded a linear Arrhenius plot with τ0 = 1.6(9) 10−7 s and
Ueff/kB = 14(1) K (Figure 4). Activation parameters are within
the experimental error from those of the bulk material,
providing conclusive evidence that fluorinated compound 2
fully retains its molecular structure and SMM behavior upon
sublimation. Noticeably, evaporated samples of
[Fe4(L)2(dpm)6] exhibit a distinctly lower barrier than the
bulk crystalline material (12.2 vs 15.6 K),5,13a pointing to more
pronounced differences between the two solid phases.
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CONCLUSIONS
■
In this work, we replaced dpm ligands in complex
[Fe4(L)2(dpm)6] with partially fluorinated β-diketonates (pta)
in order to enhance volatility with retention of SMM behavior.
Combined ToF-SIMS, XPS, and ac susceptibility measurements
provide clear evidence that the chemical structure and magnetic
properties of [Fe4(L)2(pta)6] (2) remain unvaried upon
thermal evaporation, which is effectively carried out at
temperatures as low as (440
5) K for pressures around
10−7 mbar. This new fluorinated derivative represents the
second example of an evaporable polynuclear SMM. At the
same time, it provides an excellent starting point for design of
new SMMs carrying specific surface-binding groups while
exhibiting manageable sublimation temperatures.
ASSOCIATED CONTENT
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(9) (a) Rodriguez-Douton, M. J.; Cornia, A.; Sessoli, R.; Sorace, L.;
Barra, A.-L. Dalton Trans. 2010, 39, 5851−5859. (b) Prasad, T. K.;
Poneti, G.; Sorace, L.; Rodriguez-Douton, M. J.; Barra, A.-L.;
Neugebauer, P.; Costantino, L.; Sessoli, R.; Cornia, A. Dalton Trans.
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S
* Supporting Information
Infrared spectra as KBr disks of 1 and 2, 200 MHz H NMR
1
spectrum of 2 at room temperature in benzene-d6, DFT-
optimized geometrical structures of Iso1−3, table of exper-
imental and computed distances and angles for
[Fe4(L)2(dpm)6], and computed data for Iso1−3, picture of
the molecular structure of 2 together with atom-numbering
scheme, table with selected experimental distances and angles
for 1 (PDF); X-ray crystallographic file of 2 (CIF). This
material is available free of charge via the Internet at http://
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AUTHOR INFORMATION
■
Corresponding Author
Notes
The authors declare no competing financial interest.
(14) (a) Matsumura, D.; Yokoyama, T.; Amemiya, K.; Kitagawa, S.;
Ohta, T. Phys. Rev. B 2002, 66, 024402. (b) Vollmer, R.; van Dijken,
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ACKNOWLEDGMENTS
■
(15) Viguier, R.; Serratrice, S.; Dupraz, A.; Dupuy, C. Eur. J. Inorg.
Chem. 2001, 1789−1795.
(16) Fe content was determined by complexometric titration with
EDTA, see: Jeffery, J. H.; Bassett, J.; Mendham, J.; Denney, R. C.
Vogel’s Textbook of Quantitative Chemical Analysis, 5th ed.; Longman
Group UK Limited, 1989; p 326 and following.
We thank the European Research Council for funding through
the Advanced Grant MolNanoMaS (no. 267746) and Italian
MIUR for support through FIRB project “Nanomagneti
molecolari su superfici metalliche e magnetiche per applicazioni
nella spintronica molecolare” (RBAP117RWN).
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G.; Giacovazzo, C.; Guagliardi, A.; Burla, M. C.; Polidori, G.; Camalli,
M. J. Appl. Crystallogr. 1994, 27, 435−436.
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