synthesis and magnetic characterization of fe(iii)-based 9 ...€¦ · complexes which exhibit...

SUPPORTING INFORMATION

Synthesis and Magnetic Characterization of Fe(III)-Based 9-Metallacrown-3

Complexes Which Exhibit Magnetorefrigerant Properties

Chun Y. Chow,† Régis Guillot,

§ Eric Rivière,

§ Jeff W. Kampf,

† Talal Mallah,*

,§ Vincent L.

Pecoraro*,†

†Department of Chemistry, University of Michigan, Ann Arbor, MI, 48108, USA

§Institut de Chemie Moléculaire et des Matériaux d’Orsay, CNRS, Université de Paris Sud 11,

91405 Orsay Cedex, France

Table S1. Crystallographic Details for 1-OBz and 2.

1-OBz 2

mol formula Fe4C45H39N3O18 Fe8C87.02H56.62N6O50.55

fw (g/mol) 1133.19 2441.90

cryst syst/ space group R-3 R-3

T (K) 85(2) K 100(1)

wavelength (Å) 1.54178 0.71073

a (Å) 18.44496(20) 33.2164(9)

b (Å) 18.44496(20) 33.2164(9)

c (Å) 31.7624(3) 61.4234(16)

α (deg) 90 90

β (deg) 90 90

γ (deg) 120 120

V (Å3) 9358.3(2) 58691(3)

Z 6 18

density, ρ (g/cm3) 1.206 1.244

abs coeff, µ (mm-1) 7.826 1.202

F(000) 3468 22197.1

θ range for data collection (deg) 3.097 to 73.847 1.503 to 26.488

limiting indices -22 ≤ h ≤ 2 -22≤ k ≤ 22 -38 ≤ l ≤ 38

-41≤ h ≤ 31 -41≤ k ≤ 41 -76 ≤ l ≤ 76

reflns collected/ unique 82010/4218 199732/13499

completeness to θ (%) 99.9 99.8

no. of data/ restraints/ params 4218/9/213 13499/17/752

goodness of fit on F2 1.056 0.993

final R indices [I > 2σ(I)]

R1a = 0.0431 WR2b = 0.1243

R1a = 0.0869 WR2b = 0.2277

R indices (all data) R1a = 0.0452

WR2b = 0.1274 R1a = 0.1588

WR2b = 0.2979 aR1 = Σ(||Fo| − |Fc||)/Σ|Fo|.

bwR2 = [Σ[w(Fo2− Fc

2)2]/Σ[w(F°)2]]1/2; w = 1/[σ2(Fo

2) + (mp)2+ np]; p = [max(Fo2,0) + 2Fc

2]/3 (m and n are constants); σ = [Σ[w(Fo

2− Fc2)2]/(n − p)]1/2.

Table S2. Summary of molecular weights obtained by analysis of CHN and TGA data.

Compound MW (g/mol)

1-OAc 1111.55 1-OBz 1250.92 2a 2413.88 2b 2126.37 2c 2089.32 2d 1964.75

Figure S1. Experimental PXRD pattern of 1-OAc (black) and simulated pattern (red).

Figure S2. Packing diagram of 1-OAc. Hydrogens, coordinating and lattice solvents have been omitted for clarity.

Figure S3. PXRD pattern of 1-OBz (black) and simulated pattern (red).

Figure S4. Overlaid crystal structures of 1-OAc (blue) and 1-OBz (red). Molecules were tethered at the FeIII sites.

Figure S5. Crystal packing of 1-OBz. A pair of adjacent intermolecular dimers. Blue dashed line is the central FeIII – central FeIII distance. Green dashed line represents face-to-face π-π stacking.

Figure S6. π-π interactions between adjacent intermolecular dimers of 1-OBz. For clarity the phenyl groups engaging in π-interactions are in bold.

Figure S7. Possible intermolecular π-π interactions in 2. For each molecule, there exists several potential edge-to-face and face-to-face interactions with neighboring molecules between the aromatic groups from the shi3- and isopthalate bridging ligands (bolded).

Figure S8. Packing diagram of 2 along the c-axis. Solvent channels are ca. 15 Å in diameter.

Figure S9. PXRD patterns of compound 2a. Simulated pattern (red), pattern of a fresh sample immersed in mineral oil (black) and an air dried sample (blue).

Figure S10. Energy Diagram for the spin states of the Fe4 9-MC-3 system plotted as E/|J1| vs. J2/J1. More negative E/|J1| values are lower in energy. The vertical green dashed line represents the J2/J1 ratio for 1-OAc and the vertical orange dashed line represents the J2/J1 ratio for 1-OBz. The vertical blue dashed line represents the J2/J1 ratio for 2a. The ideal J2/J1 ratio of 0.333 is represented by the vertical black dashed-dotted line.

Figure S11. χm vs. T plot for 1-OBz at a temperature range of 2 to 50 K.

Figure S12. M/NµB vs. field at temperatures between 3 and 20 K for 1-OAc (open circles), with simulated data (solid lines)

Figure S13. M/NµB vs. field at temperatures between 2 and 20 K (left) and the temperature-dependent magnetic entropy change for 2a.

Figure S14. M/NµB vs. field at temperatures between 2 and 20 K (left) and the temperature-dependent magnetic entropy change for 2b.

Figure S15. M/NµB vs. field at temperatures between 2 and 20 K (left) and the temperature-dependent magnetic entropy change for 2c.

Figure S16. M/NµB vs. field at temperatures between 2 and 20 K (left) and the temperature-dependent magnetic entropy change for 2d.

Estimation of the Molecular Weight of 1-OAc, 1-OBz, 2a, 2b, 2c and 2d

A combination of TGA, elemental analysis and PXRD was used to determine the

molecular weights of the FeIII complexes. Each compound was analyzed by TGA; the

thermolysis of each compound gave a reddish-brown powder that was determined by PXRD

(below) to be α-Fe2O3 (Hematite). The molecular weight can be determined by TGA through

back calculation using the equation:

MW = ��

��

!"��#�$�%&��'��(��)&'�

A possible formula was also determined through elemental analysis results. The average MW

from the TGA and elemental analysis was used for treating the magnetic data.

PXRD patterns for the resultant TGA product of 1-OAc (red), 1-OBz (blue) and 2 (green) and

hematite (simulated, black).

Compound 1-OAc

Elemental analysis results were: C, 33.47; H, 4.60; N, 3.78.

A potential formula derived from the CHN analysis is [Fe4(shi3-)3(acetate-

)3(MeOH)3]·MeOH·7H2O (Fe4C31H51N3O26), which gives a MW of 1105.13 g/mol

MW back calculated from the TGA is: 1117.97 g/mol

The average MW determined is: 1111.52 g/mol

TGA trace of 1-OAc.

Compound 1-OBz


A potential formula derived from the CHN analysis is [Fe4(shi3-)3(benzoate-

)3(MeOH)3]·MeOH·4H2O (Fe4C46H51N3O23), which gives a MW of 1237.29 g/mol



TGA trace of 1-OBz.

Compound 2a


A potential formula derived from the CHN analysis is [Fe8(shi3-)6(isopthalate-)3(H2O)6]·24H2O

(Fe8C66H96N6O60), which gives a MW of 2380.25 g/mol



TGA trace of 2a.

Compound 2b

Elemental analysis results were: C, 39.47; H, 3.25; N, 3.91

A potential formula derived from the CHN analysis is [Fe8(shi3-)6(isopthalate-

)3(H2O)6]·4H2O·2EtOH (Fe8C70H70N6O42), which gives a MW of 2114.07 g/mol



TGA trace of 2b.

Compound 2c


A potential formula derived from the CHN analysis is [Fe8(shi3-)6(isopthalate-

)3(H2O)6]·4H2O·EtOH (Fe8C68H62N6O41), which gives a MW of 2066.01 g/mol



TGA trace of 2c.

Compound 2d


A potential formula derived from the CHN analysis [Fe8(shi3-)6(isopthalate-)3(H2O)6]·H2O

(Fe8C66H50N6O37), which gives a MW of 1965.89 g/mol



TGA Trace of 2d.

synthesis and magnetic characterization of fe(iii)-based 9 ...€¦ · complexes which exhibit...

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