Fluorinated tetrairon(III) Single-Molecule Magnets (SMMs) [Fe-4(L-1)(2)(dpmF(6))(6)] (1dpmF(6)), [Fe-4(L-2)(2)(dpmF(6))(6)] (2dpmF(6)), and [Fe-4(L-2)(2)(pta)(6)] (2pta) were assembled combining the tripodal ligands H3L1 = 2-hydroxymethyl-2-phenylpropane-1,3-diol and H3L2 = S-5-hydroxy-4,4-bis(hydroxymethyl)pentyl ethanethioate with fluorinated beta-diketones analogues of dipivaloylmethane (Hdpm), namely 1,1,1-trifluoro-2,6,6-trimethy1-2-(trifluoromethyl)heptane-3,5-dione (HdpmF(6)) and pivaloyltrifluoroacetone (Hpta). The new compounds, along with [Fe-4(L-1)(2)(dpm)(6)] (ldpm) and [Fe-4(L-1)(2)(pta)(6)] (lpta), were designed in order to investigate the effect of fluorination degree on processability by thermal sublimation. The two different functional groups on the tripodal ligands, i.e. C6H5 in H3L1 and (CH2)(3)SAc in H3L2, are suitable for promoting physisorption and chemisorption on surfaces, respectively. Direct current magnetic data are typical for the metal-centred triangular topology of Fe-4 complexes, with antiferromagnetic nearest-neighbour coupling constants in the range 16-18 cm(-1) and an S = 5 ground spin state. Alternating current susceptibility measurements showed that slow magnetic relaxation persists in fluorinated compounds. When heated in high vacuum (10(-7) mbar), 2dpmF(6) and 2pta undergo thermal decomposition before subliming, while ldpmF(6) was found to sublimate at 497 +/- 5 K in the same conditions, being the third sublimable SMM of this family after 1pta (440 +/- 5 K) and ldpm (500 +/- 10 K).
Structure, magnetic properties and thermal sublimation of fluorinated Fe4Single-Molecule Magnets / Rigamonti, Luca; Piccioli, Marco; Nava, Andrea; Malavolti, Luigi; Cortigiani, Brunetto; Sessoli, Roberta; Cornia, Andrea. - In: POLYHEDRON. - ISSN 0277-5387. - STAMPA. - 128:(2017), pp. 9-17. [10.1016/j.poly.2017.02.036]
Structure, magnetic properties and thermal sublimation of fluorinated Fe4Single-Molecule Magnets
CORTIGIANI, BRUNETTO;SESSOLI, ROBERTA;
2017
Abstract
Fluorinated tetrairon(III) Single-Molecule Magnets (SMMs) [Fe-4(L-1)(2)(dpmF(6))(6)] (1dpmF(6)), [Fe-4(L-2)(2)(dpmF(6))(6)] (2dpmF(6)), and [Fe-4(L-2)(2)(pta)(6)] (2pta) were assembled combining the tripodal ligands H3L1 = 2-hydroxymethyl-2-phenylpropane-1,3-diol and H3L2 = S-5-hydroxy-4,4-bis(hydroxymethyl)pentyl ethanethioate with fluorinated beta-diketones analogues of dipivaloylmethane (Hdpm), namely 1,1,1-trifluoro-2,6,6-trimethy1-2-(trifluoromethyl)heptane-3,5-dione (HdpmF(6)) and pivaloyltrifluoroacetone (Hpta). The new compounds, along with [Fe-4(L-1)(2)(dpm)(6)] (ldpm) and [Fe-4(L-1)(2)(pta)(6)] (lpta), were designed in order to investigate the effect of fluorination degree on processability by thermal sublimation. The two different functional groups on the tripodal ligands, i.e. C6H5 in H3L1 and (CH2)(3)SAc in H3L2, are suitable for promoting physisorption and chemisorption on surfaces, respectively. Direct current magnetic data are typical for the metal-centred triangular topology of Fe-4 complexes, with antiferromagnetic nearest-neighbour coupling constants in the range 16-18 cm(-1) and an S = 5 ground spin state. Alternating current susceptibility measurements showed that slow magnetic relaxation persists in fluorinated compounds. When heated in high vacuum (10(-7) mbar), 2dpmF(6) and 2pta undergo thermal decomposition before subliming, while ldpmF(6) was found to sublimate at 497 +/- 5 K in the same conditions, being the third sublimable SMM of this family after 1pta (440 +/- 5 K) and ldpm (500 +/- 10 K).File | Dimensione | Formato | |
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