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Accorsi S, Barra AL, Caneschi A, et al. Tuning anisotropy barriers in a family of tetrairon(III) single-molecule magnets with an S = 5 ground state. J Am Chem Soc. 2006;128(14):4742-55doi: 10.1021/ja0576381.
Accorsi, S., Barra, A. L., Caneschi, A., Chastanet, G., Cornia, A., Fabretti, A. C., Gatteschi, D., Mortalo, C., Olivieri, E., Parenti, F., Rosa, P., Sessoli, R., Sorace, L., Wernsdorfer, W., & Zobbi, L. (2006). Tuning anisotropy barriers in a family of tetrairon(III) single-molecule magnets with an S = 5 ground state. Journal of the American Chemical Society, 128(14), 4742-55. https://doi.org/10.1021/ja0576381
Accorsi, Stefania, et al. "Tuning anisotropy barriers in a family of tetrairon(III) single-molecule magnets with an S = 5 ground state." Journal of the American Chemical Society vol. 128,14 (2006): 4742-55. doi: https://doi.org/10.1021/ja0576381
Accorsi S, Barra AL, Caneschi A, Chastanet G, Cornia A, Fabretti AC, Gatteschi D, Mortalo C, Olivieri E, Parenti F, Rosa P, Sessoli R, Sorace L, Wernsdorfer W, Zobbi L. Tuning anisotropy barriers in a family of tetrairon(III) single-molecule magnets with an S = 5 ground state. J Am Chem Soc. 2006 Apr 12;128(14):4742-55. doi: 10.1021/ja0576381. PMID: 16594711.
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J Am Chem Soc. 2006 Apr 12;128(14):4742-55. doi: 10.1021/ja0576381.

Tuning anisotropy barriers in a family of tetrairon(III) single-molecule magnets with an S = 5 ground state.

Journal of the American Chemical Society

Stefania Accorsi, Anne-Laure Barra, Andrea Caneschi, Guillaume Chastanet, Andrea Cornia, Antonio C Fabretti, Dante Gatteschi, Cecilia Mortalo, Emiliano Olivieri, Francesca Parenti, Patrick Rosa, Roberta Sessoli, Lorenzo Sorace, Wolfgang Wernsdorfer, Laura Zobbi

Affiliations

  1. INSTM and Department of Chemistry, University of Modena and Reggio Emilia, via G. Campi 183, 41100 Modena, Italy.

PMID: 16594711 DOI: 10.1021/ja0576381

Abstract

Tetrairon(III) Single-Molecule Magnets (SMMs) with a propeller-like structure exhibit tuneable magnetic anisotropy barriers in both height and shape. The clusters [Fe4(L1)2(dpm)6] (1), [Fe4(L2)2(dpm)6] (2), [Fe4(L3)2(dpm)6].Et2O (3.Et2O), and [Fe4(OEt)3(L4)(dpm)6] (4) have been prepared by reaction of [Fe4(OMe)6(dpm)6] (5) with tripodal ligands R-C(CH2OH)3 (H3L1, R = Me; H3L2, R = CH2Br; H3L3, R = Ph; H3L4, R = tBu; Hdpm = dipivaloylmethane). The iron(III) ions exhibit a centered-triangular topology and are linked by six alkoxo bridges, which propagate antiferromagnetic interactions resulting in an S = 5 ground spin state. Single crystals of 4 reproducibly contain at least two geometric isomers. From high-frequency EPR studies, the axial zero-field splitting parameter (D) is invariably negative, as found in 5 (D = -0.21 cm(-1)) and amounts to -0.445 cm(-1) in 1, -0.432 cm(-1) in 2, -0.42 cm(-1) in 3.Et2O, and -0.27 cm(-1) in 4 (dominant isomer). The anisotropy barrier Ueff determined by AC magnetic susceptibility measurements is Ueff/kB = 17.0 K in 1, 16.6 K in 2, 15.6 K in 3.Et2O, 5.95 K in 4, and 3.5 K in 5. Both |D| and U(eff) are found to increase with increasing helical pitch of the Fe(O2Fe)3 core. The fourth-order longitudinal anisotropy parameter B4(0), which affects the shape of the anisotropy barrier, concomitantly changes from positive in 1 ("compressed parabola") to negative in 5 ("stretched parabola"). With the aid of spin Hamiltonian calculations the observed trends have been attributed to fine modulation of single-ion anisotropies induced by a change of helical pitch.

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