Verdazyl Radical as Building Block for a Six Spin Centers 2p-3d-4f Single-Molecule Magnet

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1 Supporting Information (SI) for the manuscript: Verdazyl Radical as Building Block for a Six Spin Centers p-d-f Single-Molecule Magnet Ghénadie Novitchi, Sergiu Shova, Yanhua Lan, Wolfgang Wernsdorfer and Cyrille Train*, Laboratoire National des Champs Magnétiques Intenses, UPR CNRS, Université Grenoble-Alpes, B.P., Grenoble cedex 9, France Petru Poni Institute of Macromolecular Chemistry, Aleea Gr. Ghica Voda A, 77 Iasi, Romania Institut Néel, UPR CNRS 9, Université Grenoble-Alpes, B.P., Grenoble cedex 9, France S

2 Experimental Section Materials. All chemicals were of reagent grade quality. They were purchased from commercial sources and used as received. Bis(-methylhydrazide)carbonic acid was prepared by a previously reported method []. Synthesis of,5-dimethyl--( -(hydroxymethyl)- -pyridine)--oxotetrazane (H vdpych OH). g (.9 mmol) -(hydroxymethyl)--pyridinecarbaldehyde was dissolved in ml methanol by refluxing. The resulting solution was added dropwise into a ml methanolic solution containing.5 g (.9 mmol) of bis(-methylhydrazide)carbonic acid. The reaction mixture was refluxed overnight. After refluxing, the reaction mixture was cooled, evaporated and recrystallized from dichloromethane. Yield =.9 g; % Yield = 7.. Anal. Calcd for C H 5 N 5 O (M 7 g mol ), %: C, 5.; H,.7; N, 9.5;. Found, %: C, 5.; H,.; N, 9.; 5 NH -CH - -CH CH CH+ 5 CH -OH CH (ppm) Figure S H NMR ( MHz) spectra of,5-dimethyl--( -(hydroxymethyl)- -pyridine)-- oxotetrazane (H vdpych OH) in d -DMSO at room temperature. 5 -CH C+C=O+ C CH+ CH+ 5 CH -CH - CH d -DMSO H decoupled C NMR C NMR 75.MHz d -DMSO t= C C-DEPT (ppm) Figure S C NMR (75. MHz) spectra of,5-dimethyl--( -(hydroxymethyl)- -pyridine)-- oxotetrazane (H vdpych OH) in d -DMSO at room temperature. S

3 7 %T Nombre d'onde (cm-) Figure S. FTIR spectra (in KBr) of,5-dimethyl--( -(hydroxymethyl)- -pyridine)-- oxotetrazane (H vdpych OH) Synthesis of (vdpych O) Co Dy Ac (). g (.5 mmol) of H vdpych OH was dissolved in 5 ml of acetonitirile. To this solution, was added. g (. mmol) of cobalt(ii) acetate tetrahydrate and. g (.5 mmol) dysprosium(iii) acetate monohydrate. The reaction mixture was stirred during half an hour to obtain a clear solution. Then the mixture was filtered. The filtrate was left for a few hours at room temperature to yield crystals of the desired compound. Yield =.5 g; % Yield =.. Anal. Calcd for C H Co Dy N O (M.7 g mol ), %: C,.9; H,.; N,.;. Found, %: C,.; H,.; N,.. S

4 %T %T Nombre d'onde (cm-) Nombre d'onde (c m-) Figure S. FTIR spectra (in KBr) of. Physical Techniques. The FTIR spectra were obtained using the Nicolet Fourier Transform Infra- Red (FTIR) spectrophotometer is 5 IR. The FTIR spectra were recorded in KBr pallets with scans per spectrum at a resolution of cm. The H, C NMR spectra were recorded on Bruker Avance II spectrometers at ( H) and 75. ( C) MHz, respectively. The H and C chemical shifts were referred to the residual signals from the solvent as reference. Deuterated solvent DMSO-d was from Sigma-Aldrich. X-ray crystallography. Crystallographic measurements for were carried out on Oxford-Diffraction XCALIBUR E CCD diffractometer equipped with graphite-monochromated MoKα radiation. A single crystal was positioned at mm from the detector and 7 frames were measured each for s over scan width. The unit cell determination and data integration were carried out using the CrysAlis package of Oxford Diffraction []. The structures was solved by direct methods using Olex [] software with the SHELXS structure solution program and refined by full-matrix least-squares on F² with SHELXL-97 [] with anisotropic displacement parameters for non-hydrogen atoms. All H atoms introduced in idealized positions (d CH =.9 Å) using the riding model with their isotropic displacement parameters fixed at % of their riding atom. The main crystallographic data together with refinement details are summarized in Table S. CCDC 999 contains the supplementary crystallographic data for this contribution. These data can be obtained free of charge via (or from the Cambridge Crystallographic Data Centre, Union Road, Cambridge CB EZ, UK; fax: (+) --; or deposit@ccdc.ca.ac.uk). S

5 Table S. Crystallographic data, details of data collection and structure refinement parameters for. Empirical formula C H CoDyN 5 O Formula weight 9. Temperature/K 7 Crystal system triclinic Space group P- a/å.() b/å.95() c/å.79() α/.59() β/ 9.9(9) γ/ 7.(5) V/Å 7.7() Z D calc /mg/mm.95 µ/mm -.95 Crystal size/mm... θ min, θ max( o ).7 to 5.5 Reflections collected 7 Independent reflections 7[R int =.7] Data/restraints/parameters 7// R a (I>σ(I).7 wr b (all data). GOF c.9 Largest diff. peak/hole/e Å -.5/-. a R = Σ F o - F c /Σ F o, b wr = {Σ[w (F o - F c ) ] /Σ[w(F o ) ]} /. c GOF = {Σ[w(F o - F c ) ] /(n p)} /, where n is the number of reflections and p is the total number of parameters refined. Figure S5 Coordination polyhedrons of Co II and Dy III. The bold gold dashed lines indicates the longest Co-X (X=N,O) bond lengths. S5

6 Figure S View of crystal structure showing π stacking. Centroid-to-centroid distances (. Å) are shown in black dashed lines. Magnetic Measurements. Variable-temperature (. K) direct current (dc) and alternative current (ac) magnetic susceptibility and magnetization measurements were carried out on slightly crushed polycrystalline sample with a Quantum Design SQUID magnetometer. The dc susceptibility was measured using an applied field of. T. Variable-temperature (. K) and frequency (-5 Hz) ac magnetic susceptibility measurements were carried out under zero and. T applied static fields. The magnetic susceptibility data were corrected for the diamagnetism of the constituent atoms and the sample holder contribution [5]. The relaxation times (τ) was obtained after fitting of χ (ν) and χ (ν) components according to the modified Debye function according to equations () and () respectively []. The data and the fit are presented in figures S and S9 whereas the parameters extracted from the fit are given in tables S and S. α χ ) [ + ( πν acτ) sin( απ / ) ] α ( α ) ( πν τ) sin( απ / ) + ( πν τ) ( χ χ' ( ν ac ) = χ + (S) + ac α ( χ χ )( πν acτ) cos( απ / ) α ( α ) ( πν τ) sin( απ / ) + ( πν τ) χ' '( ν ac ) = (S) + ac ac ac S

7 5 χ M T (cm mol - K) M(Nβ) K. K. K 5. K H(T) T(K) Figure S7 Temperature dependence of the χ M T product; inset: magnetizations as function of applied field measured at indicated temperatures for. χ''(cm mol - ) χ'(cm mol - ) 9.. K H dc = koe 7 5 ' H dc = koe K.5.5 ' χ'(cm mol - ) χ''(cm mol - ) K H dc =. koe ' H dc =. koe K.5 ' Figure S. Frequency dependence of the in-phase (top) and out-of-phase (bottom) components of the ac magnetic susceptibility data for under. (left) and. T (right) dc field. The solid lines are the best fits according the modified Debye function (eqs (S) and (S)). S7

8 χ''(cm mol - ) χ'(cm mol - ) χ''(cm mol - ) exp. K χ'(cm mol - ) exp. K ' exp. K ' χ'(cm mol - ) χ''(cm mol - ) χ''(cm mol - ) exp.9k χ'(cm mol - ) exp.9k ' ' ' exp.9k ' ' ' ' ' ' χ''(cm mol - ) χ'(cm mol - ) χ''(cm mol - ) exp. K χ'(cm mol - ) exp. K ' ' ' exp. K Figure S9a. Representative example of Cole-Cole plot (top), frequency-dependence of the in-phase and out-of-phase (bottom) components of the ac magnetic susceptibility data for under zero dc field. The solid lines are the best fits according the modified Debye function (eqs (S) and (S))..E E+.E+ χ''(cm mol - ) exp. K χ''(cm mol - ) exp. K χ''(cm mol - ) exp. K.5E+.E+.5E+.E+ 5.E-.E+ χ'(cm mol - ) χ'(cm mol - ) χ'(cm mol - ) χ'(cm mol - ) χ'(cm mol - ) χ'(cm mol - ) χ''(cm mol - ) exp. K ' ' ' ' exp. K ' ' ' '.5.5 χ''(cm mol - ) exp. K exp. K.5.5 χ''(cm mol - ).5.5 exp. K '.E+.5 exp.5e+.e+.5.5e+.e+.5.5e+.e+.5 5.E-.E+ ' ' ' Figure S9b. Representative example of Cole-Cole plot (top), frequency-dependence of the in-phase and out-of-phase (bottom) components of the ac magnetic susceptibility data for under zero dc field. The solid lines are the best fits according the modified Debye function (eqs (S) and (S)). S

9 .E+.E+.E+.5.5E+.5.5E+.5.5E+.E+.E+.E+ χ''(cm mol - ) exp. K.5E+.E+.5E+.E+ 5.E- χ''(cm mol - ) exp.5 K.5E+.E+.5E+.E+ 5.E- χ''(cm mol - ) exp. K.5E+.E+.5E+.E+ 5.E-.E+.E+.E+ χ'(cm mol - ) χ'(cm mol - ) χ'(cm mol - ) χ'(cm mol - ) χ'(cm mol - ) χ'(cm mol - ) χ''(cm mol - ) exp. K ' ' exp. K.E+ ' ' '.E+.5E+.E+.5E+.E+.5E+.E+ 5.E- χ''(cm mol - ) exp.5 K ' ' ' exp.5 K.E+ ' ' '.E+.5E+.E+.5E+.E+.5E+.E+ 5.E- χ''(cm mol - ) ' ' ' exp. K exp. K.E+ ' ' '.E+.5E+.E+.5E+.E+.5E+.E+ 5.E- Figure S9c. Representative example of Cole-Cole plot (top), frequency-dependence of the in-phase and out-of-phase (bottom) components of the ac magnetic susceptibility data for under zero dc field. The solid lines are the best fits according the modified Debye function (eqs (S) and (S)). S9

10 Table S results of the fits of ac susceptibility for under H dc =. T according the modified Debye functions (eqs (S) and (S)). Temperatures Parameters Values Std. Dev. R.K.9K.K.K.K.K.K.5K.K χ.77. χ.7.7 τ.95.5e- α χ.95.5 χ..7 τ..7e- a.7.9 χ.95.7 χ..599 τ.7.7e- α χ.9. χ..55 τ..e-7 α χ χ τ..e- α.7.97 χ χ τ.5 7.E-7 α χ χ..5 τ..e- α χ χ τ..57e- α..959 χ.599. χ.55. τ 9.5E-5.E- α E- 7.5E-.E-.E-.E-.E-.E-.7E-.7E- S

11 Table S results of the fits of ac susceptibility for under H dc =. T according the modified Debye functions (eqs (S) and (S)). Temperatures Parameters Values Std.Dev. R.K.K.K.K.K.K.K.K.K.K.K χ.7.5 χ τ.759.5e-5.e+ α.. χ.9.5 χ τ.99.e-5.5e+ α χ χ 5.. τ.7.7e-5.e+ α χ..77 χ..9 τ.797.e-5.7e+ α.7.55 χ χ.55.9 τ.55.e-5.5e+ α χ χ τ.57.e-5.77e+ α.759. χ.99.5 χ τ.77 7.E-.7E+ α..7 χ.9.59 χ.7.9 τ E-.E+ α χ.9. χ.9.79 τ..e-.9e+ α χ.7.79 χ τ..e-.e+ α χ χ.5.99 τ.57.e-.e+ α Further magnetization measurements were performed with an array of micro-squids [7]. This magnetometer works in the temperature range of. to ca. 7 K and in fields up to. T with sweeping rates as high as. T s -. The time resolution is approximately ms. The magnetic field can be applied in any direction of the micro-squid plane with precision much better than. by separately driving three orthogonal coils. In order to ensure good thermalization, each sample was fixed with apiezon grease. S

12 Figure S Magnetization vs. magnetic field hysteresis loops for a single crystal of at a sweep rate of. T/s at various temperatures (left) and a zoom view of the loops (right). The magnetization is normalized to its saturation value M s at. T. References. Barr, C. L.; Chase, P. A.; Hicks, R. G.; Lemaire, M. T.; Stevens, C. L., Synthesis and characterization of verdazyl radicals bearing pyridine or pyrimidine substituents: A new family of chelating spin-bearing ligands. J. Org. Chem. 999,, CrysAlis RED, Oxford Diffraction Ltd.,Version.7..7,.. Dolomanov, O. V.; Bourhis, L. J.; Gildea, R. J.; Howard, J. A. K.; Puschmann, H., OLEX: a complete structure solution, refinement and analysis program. J. Appl. Crystallogr. 9,, 9-.. Sheldrick, G., A short history of SHELX. Acta Crystallographica Section A,, (a) Kahn, O., Molecular Magnetism. VCH Publishers, Inc.: New York, Weinheim, Cambridge, 99; (b) Pascal, P., Magnochemical studies. Annales Chim. Phys. 9, 9, Gatteschi, D.; Sessoli, R.; Villain, J., Molecular Nanomagnets. Oxford University Press,: Oxford,. 7. (a) Wernsdorfer, W., Classical and quantum magnetization reversal studied in nanometersized particles and clusters. Advances in Chemical Physics,, 99-9; (b) Wernsdorfer, W., From micro- to nano-squids: applications to nanomagnetism. Superconductor Science & Technology 9,. S