The magnetic properties of the 5f5 [tris-(tri-1-pyrazolylborato)–plutonium(III)] complex have been investigated by ac susceptibility measurements, showing it to be the first plutonium single-molecule magnet; its magnetic relaxation slows down with decreasing temperature through a thermally activated mechanism followed by a quantum tunnelling regime below 5 K.JRC.E.6 - Actinide researc

APOSTOLIDIS Christos

CACIUFFO Roberto

COLINEAU Eric

GRIVEAU Jean-Christophe

MAGNANI Nicola

WALTER Olaf

Chemical Communications

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Electronic Supplementary information for 'A plutonium-based single-molecule magnet'N. Magnani, E. Colineau, J.-C. Griveau, C. Apostolidis, O. Walter, R. CaciuffoEuropean Commission, Joint Research Centre, Institute for Transuranium Elements, Postfach 2340, 76125 Karlsruhe, Germany1. SynthesisThe solvents were purchased from Aldrich in their anhydrous form conditioned under argon. The potassium salt of the ligand (KTp) was prepared as previously described.[S1] The room-temperature reaction of 1 equiv. of PuCl3 with 3.05 equivalents of KTp in water leads to the precipitation of PuTp3. Purification proceeds via washing with water, ethanol, and diethylether and drying of the residue. Extraction with benzene yields in 90 % of single crystalline material. Elemental analysis (%) calculated for 239PuTp3 (B3C27H30N18Pu; 878.069 g/mol) C 36.97; H 3.45; N 28.74; Pu 27.21. Found Pu 27.5.2. Spectroscopic dataFTIR and Solid state UV-NIR spectra were recorded respectively on a Perkin-Elmer 2000 IR-spectrometer and on a Perkin-Elmer Lambda 9 spectrometer. The observed transitions are listed in the following.IR (KBr; cm-1): 3142(m), 3119(w), 3112(w), 2453(sh), 2442(s), 2405(m), 2374(w), 1505(s), 1431(m), 1423(m), 1406(s), 1381(s), 1301(vs), 1293(vs), 1226(m), 1212(vs), 1197(m), 1185(m), 1129(m), 1121(vs), 1085(w), 1061(m), 1048(vs), 974(vs), 924(w), 920(w), 899(w), 878(w), 804(w), 777(m), 769(vs), 750(vs), 739(m), 725(vs), 670(m), 625(m), 620(m)FIR (Polyethylen; cm-1): 338(m), 332(m), 319(m), 260(w), 182(m), 161(m), 136(vs) (w = weak, m = medium, s = strong, vs = very strong)Solid state UV-NIR spectrum taken on a Perkin-Elmer Lambda 9 spectrometer.NIR/VIS (KBr; nm): 1556, 1413, 1189, 1147, 1100, 1049, 1023, 928, 912, 822, 814, 805, 796, 774, 768, 669, 605, 565, 511.1Electronic Supplementary Material (ESI) for ChemComm.This journal is © The Royal Society of Chemistry 20143. X-Ray CrystallographyDiffraction data were measured at 100 K on a Bruker APEX II Quazar diffractometer (Mo-Kα radiation, graphite monochromator, λ = 0.71073 Å) in the Ω-range from 1.48 to 28.452°. 2844 frames were collected with an irradiation time of 3 s per frame obtained from eight runs performed with - or -scans with  =   = 0.5°. The data were integrated with SAINT[S2] and corrected to Lorentz and polarisation effects; absorption effects were corrected with SADABS.[S3] The structure was solved by direct methods and refined to an optimum R1 value with SHELXL-2013.[S4] Visual evaluation was performed with XPMA.[S5] Refinement of F2 proceeded against all reflections. Data have been deposited at the CCDC with the reference number 994710, and are available on request from http://www.ccdc.cam.ac.uk/.Table S1. Crystallographic data._____________________________________________________ Empirical formula B3C27H30N18PuFormula weight 878.09Temperature 100(2) KWavelength 0.71073 ÅCrystal system HexagonalSpace group P 63/mUnit cell dimensions a = 11.7036(5) Åc = 13.5561(8) ÅVolume 1608.07(17) Å3Z 2Density (calculated) 1.814 Mg/m3Absorption coefficient 2.102 mm-1F(000) 854Crystal size 0.118 x 0.068 x 0.064 mm3Ω range for data collection 2.009 to 28.452°Index ranges -15 ≤ h≤ 15, -15 ≤  k ≤ 15, -18 ≤ l ≤ 17Reflections collected 28954Independent reflections 1381 [R(int) = 0.0502]Completeness to theta = 25.000° 99.9 % Absorption correction multi-scanMax. and min. transmission 0.922 and 0.862Refinement method Full-matrix least-squares on F2Data / restraints / parameters 1381 / 0 / 108Goodness-of-fit on F2 1.065Final R indices [I>2sigma(I)] R1 = 0.0149, wR2 = 0.0311R indices (all data) R1 = 0.0178, wR2 = 0.0318Largest diff. peak and hole 0.593 and -0.661 eÅ-32Table S2. Bond lengths [Å] and angles [°].*_____________________________________________________ Pu(1)-N(1) 2.5883(15)Pu(1)-N(3) 2.762(2)N(1)-C(1) 1.336(2)N(1)-N(2) 1.373(2)N(2)-C(3) 1.351(2)N(2)-B(1) 1.544(2)N(3)-C(4) 1.338(3)N(3)-N(4) 1.369(3)N(4)-C(6) 1.342(3)N(4)-B(1) 1.530(4)C(1)-C(2) 1.389(3)C(2)-C(3) 1.372(3)C(4)-C(5) 1.400(4)C(5)-C(6) 1.370(4)B(1)-N(2)#1 1.544(2)N(1)#1-Pu(1)-N(1)#2 84.13(5)N(1)#1-Pu(1)-N(1)#3 134.49(2)N(1)#2-Pu(1)-N(1)#3 78.64(7)N(1)#1-Pu(1)-N(3)#4 67.53(4)N(1)#2-Pu(1)-N(3)#4 140.68(3)N(1)#4-Pu(1)-N(3)#4 66.96(4)N(3)#4-Pu(1)-N(3) 120.0C(1)-N(1)-N(2) 105.62(15)C(1)-N(1)-Pu(1) 129.29(12)N(2)-N(1)-Pu(1) 123.64(11)C(3)-N(2)-N(1) 109.44(15)C(3)-N(2)-B(1) 127.25(17)N(1)-N(2)-B(1) 123.15(16)C(4)-N(3)-N(4) 105.1(2)C(4)-N(3)-Pu(1) 132.14(17)N(4)-N(3)-Pu(1) 122.72(15)C(6)-N(4)-N(3) 110.7(2)C(6)-N(4)-B(1) 128.4(2)N(3)-N(4)-B(1) 120.8(2)N(1)-C(1)-C(2) 111.55(17)C(3)-C(2)-C(1) 104.45(17)N(2)-C(3)-C(2) 108.94(17)N(3)-C(4)-C(5) 111.1(2)C(6)-C(5)-C(4) 104.7(2)N(4)-C(6)-C(5) 108.3(2)N(4)-B(1)-N(2) 108.41(14)N(2)#1-B(1)-N(2) 112.5(2)_____________________________________________________________ * Symmetry transformations used to generate equivalent atoms: #1 x,y,-z+3/2 ;   #2 -y+1,x-y+1,-z+3/2 ;   #3 -y+1,x-y+1,z;  #4 -x+y,-x+1,z    Unlisted distances or angles are identical to ones already present in the table.3Figure S1. Cell packing along the c axis of PuTp3. Plutonium atoms are shown in blue, nitrogen in violet, and boron ions are shown in pink. 4. Magnetic characterizationThe temperature-dependent dc magnetic susceptibility has been measured in the temperature range from 1.9 to 300 K with a Quantum Design MPMS-7T Superconducting Quantum Interference Devices (SQUID). Susceptibility data have been collected with applied magnetic fields µ0H ranging from 0.05 to 7 T on a sample of 58.15 mg using compressed powder in a Suprasil-Quartz sample holder. The sample was restrained to prevent grain torqueing using a fitted quartz stopper, and was sealed under argon before measurement. The contribution to the signal of the empty sample holder was measured before the encapsulation and subtracted from the total signal. The susceptibility has been obtained as the ratio between the longitudinal magnetization and the applied magnetic field. The resulting data were corrected for the diamagnetic contribution using tabulated Pascal’s constants. Magnetic calibration was done with a cylindrical palladium standard having approximately the same geometry of the measured samples. The real and imaginary parts of the ac magnetic susceptibility were measured as a function of temperature on the same sample using a Quantum Design PPMS-14T platform; data for this experiment were collected on warming from 1.9 to 40 K, after zero-field cooling of the sample. For each run of measurements, the excitation a.c. field was applied with a fixed amplitude of µ0Hac = 10 G and fixed frequencies f, ranging from 18 to 9987 Hz. The temperature of the samples was controlled with an accuracy of about 0.1 K.4Figure S2. Frequency dependence of the a.c. magnetic susceptibility measured for PuTp3 at various temperature and field values (see text for details). Isotherms of the frequency dependent a.c. magnetic susceptibility have also been measured at several temperatures from 1.9 to 12 K in the frequency range from 18 Hz to about 10 kHz, both with and without a superimposed field (0Hdc = 0, 100 Oe, 2000 Oe), generated by a superconducting d.c. magnet. The results obtained with field 0Hdc = 100 Oe have been fitted to a modified Debye relaxation law valid in the low frequency range and allowing for a continuous distribution of the relaxation time S6]                                                     S1      11 cSTSac iWhere T is the isothermal susceptibility in the limit << 1, S = ac() is the adiabatic susceptibility,  = 2f is the angular frequency and c is the average relaxation time. The 5parameter  determines the width of the time relaxation distribution function g(ln). Equation S1 can be separated into real and imaginary components corresponding to the in-phase and out-of-phase susceptibilities                            S2            2/sinln1coshln1sinh12 ccSTSacand                                  S3          .2/sinln1cosh2/cos2  cSTacTable S3. Parameters obtained by fitting Cole-Cole plots to the modified Debye relaxation model.T  (K) S (10-3 emu/mol) T (10-3 emu/mol) c (s) 1.9 9.12 22.34 66.4 0.1663.0 6.20 17.09 56.5 0.1754.0 4.86 13.69 43.9 0.2145.0 3.57 11.45 30.4 0.2836.0 2.16   9.40 17.6 0.3347.0 1.36   8.16 11.9 0.3688.0 0.63   7.12 7.82 0.4059.0 0.32   6.34 5.56 0.41610.0 0.04   5.47 3.92 0.36812.0 0.05   4.42 2.65 0.341The parameters obtained from the fits are reported in Table S3, and the corresponding distribution function for the relaxation times on a logarithmic scale is given by                                  S4          .cos/ln1coshsin21ln   cgAs an example, the g(ln) distribution obtained at 1.9 and 12 K are shown in the inset of Fig. 4. The  parameter increases with increasing temperature, thus the distribution function g(ln) becomes progressively broader. 65. Additional references[S1] a) S. Trofimenko, J. Am. Chem. Soc. 1967, 89, 3165; b) S. Trofimenko, Inorg. Synth. 1970, 12, 99.[S2] SAINT: Bruker 2007,  Bruker AXS Inc., Madison, Wisconsin, USA.[S3] SADABS: Bruker 2007,  Bruker AXS Inc., Madison, Wisconsin, USA.[S4] SHELXL-2013: G. M. Sheldrick, 2013, University of Göttingen, Germany.[S5] XPMA: L. Zsolnai, 1997, University of Heidelberg, Germany.[S6] a) D. Huser, A. J. Vanduyneveldt, G. J. Nieuwenhuys, J. A. Mydosh, J. Phys. C: Solid State Phys. 1986, 19, 3697; b) U. T. Hochli, Phys. Rev. Lett. 1982, 48, 1494.7

A plutonium-based single-molecule magnet

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