Sandwich-Type Tb and Dy Complexes with Schiff-Base Ligand: Syntheses, Crystal Structures and Magnetic Properties

1.
College of Chemistry and Environmental Engineering, Anyang Institute of Technology, Anyang, Henan 455000, China
2.
School of Chemistry and Chemical Engineering, Liaocheng University, Liaocheng, Shandong 252000, China

Corresponding author: YANG Li-Guo, lgyang@ayit.edu.cn

Received Date: 15 May 2018
Revised Date: 14 July 2018
Available Online: 10 October 2018

Abstract: Two new sandwich-type di-lanthanide complexes[M₂L₃(H₂O)] (M=Tb (1), Dy (2), H₂L=N, N'-bis(4-methyloxysalicylidene)benzene-1, 2-diamine) were synthesized by treating the Schiff-base ligand with M(acac)₃·6H₂O (M=Tb, Dy) and characterized by elemental analysis, IR spectra and X-ray single crystal diffraction. X-ray single crystal diffraction analysis reveals that 1 and 2 have a similar new triple-deck dinuclear sandwich structure. The magnetic measurements of complexes 1 and 2 indicated that 1 and 2 exhibit the antiferromagnetic interactions between lanthanide ions, and field-induced slow magnetic relaxation. The deduced effective energy barrier (U_eff) and relaxation time (τ₀) are 35.45 cm^-1 and 2.7×10^-10 s for 2.

Key words:

0. Introduction

Single Molecule Magnets (SMMs), first emerging in a dodecametallic manganese-acetate (Mn₁₂) with the slow relaxation of magnetization at low temperature^[1-2], have attracted considerable attention due to the potential applications in high-density information storage^[3], molecule-based spintronic devices^[4], quantum computing devices^[5] and refrigeration devices^[6]. Two important factors for the design of SMMs involve the large spin ground state (S) and uniaxial (negative) magnetic anisotropy (D), leading to an anisotropy energy barrier (U_eff)^[7]. With the large ground-state spin values, lots of polynunclear transition metal complexes have been synthesized as new SMMs to study the two ingredients (S and D)^[8]. But in recent years, the lanth-anide ions such as Dy(Ⅲ) and Tb(Ⅲ) are widely studied due to their large intrinsic magnetic anisotropy which increase the D values for the complexes resulting in higher energy barriers compared to SMMs with 3d metals^[9]. So various lanthanide SMMs complexes have been synthesized, and one of the Dy SMMs has the largest effective energy barrier of 528 K in multinuclear SMMs^[10]. In addition, the ligand field as well as the coordination geometry strongly influences the local anisotropy of the lanthanide ion. That is to say, the interplay between the ligand field effect, the geometry, and the strength of the magnetic interaction between the lanthanide sites will govern the SMM behavior^[11]. Thus, it is necessary to study the magnetic interactions between the bridging ligand and the lanthanide ions.

Lots of organic ligands have been synthesized for discrete SMMs, for example, polyalcohols^[10], carboxylic acid derivatives^[12], oximate derivatives^[13], and Schiff-base ligands^[14]. These polydentate ligands can mediate the magnetic interactions between the metallic centers. Recently, several sandwich-type complexes with Schiff-base ligands have been reported^[15], however, only one of them shows SMM behavior^[16]. Furthermore, to the best of our knowledge, the sandwich-type complex with Schiff base ligand N, N′-bis(4-methyloxysalicyli-dene)benzene-1, 2-diamine(H2L) has not been reported.

In order to enlarge the structure database and further explore the magnetic interactions between the bridge group and lanthanide ions, two new triple-deckers sandwich complexes [M₂L₃(H₂O)] (M=Tb (1), Dy (2)) with Schiff base ligand have been synthesized and characterized by X-ray single crystal diffraction. Complexes 1 and 2 show the antiferromagnetic couple. The slow relaxation and strong quantum tunneling of magnetization exist for 1 and 2. The deduced effective energy barrier(U_eff) and relaxation time (τ₀) of 2 are 35.45 cm^-1 and 2.7×10^-10 s.

1. Experimental

1.1 Chemicals and instruments

The ligand H₂L was prepared according to the published procedures^[16]. All other reagents and solvents were used as received.

Elemental analyses were performed on an Elementar Vario MICRO CUBE elemental analyzer. Thermogravimetric analysis (TGA) experiments were carried out on a NETZSCH STA 449F3 thermal analyzer. IR spectrum was recorded as KBr discs on a Shimadzu IR-408 infrared spectrophotometer. Magnetic data was collected on magnetic measurement system MPMS-XL 7.

1.2 Synthesis of [Tb₂L₃(H₂O)] (1)

Tb(OAc)₃·6H₂O (199.2 mg, 0.2 mmol) and H₂L (112.9 mg, 0.3 mmol) were mixed in methanol (10 mL) in the presence of tetramethyl ammonium hydroxide. The solution was stirred for 5 h at room temperature and filtered. The filtrate was left undisturbed to allow slow evaporation of the solvent. Yellow single crystals suitable for X-ray diffraction were obtained after a week. Yield: 36 mg, 41.2% (based on Tb). IR (KBr cm^-1): 3 636 (br), 2 362 (s), 1 678 (s), 1 602 (m), 1 575 (s), 1 526 (s), 1 440 (vs), 1 381 (s), 1 357 (w), 1 310(m), 1 234 (m), 1 201 (m), 1 116 (vw), 1 034 (vw), 971 (vw), 831 (w), 786 (vw), 735 (w), 650 (w), 612 (w). Anal. Calcd. for 1·DMF (C₆₉H₆₃Tb₂O₁₄N₇, %): C, 54.08; H, 4.05; N, 6.40. Found(%): C, 54.11; H, 4.09; N, 6.35.

1.3 Synthesis of [Dy₂L₃(H₂O)] (2)

Complex 2 was obtained by following the procedure for 1 except that Dy(OAc)₃·6H₂O (199.9 mg, 0.2 mmol) was used instead of Tb(OAc)₃·6H₂O. Yellow single crystals suitable for X-ray diffraction were obtained after a week. Yield: 30 mg, 40% (based on Dy). IR (KBr cm^-1): 3 652 (br), 2 989(s), 1 602(s), 1 578 (s), 1 524 (vs), 1 440 (s), 1 384(m), 1 312 (m), 1 299 (m), 1 183 (vw), 1 116 (vw), 1 029 (w), 978 (vw), 831 (w), 755 (w), 739 (w), 659 (w), 605 (w). Anal. Calcd. for [Dy₂L₃(H₂O)]₄·3DMF·7H₂O (C₂₇₃H₂₅₉Dy₈N₂₇O₆₂, %): C, 52.75; H, 4.17; N, 6.09. Found(%): C, 52.67; H, 4.09; N, 6.11.

1.4 X-ray crystallography

The crystal data were collected on an Oxford Diffraction Gemini E system with a Cu Kα sealed tube (λ=0.154 18 nm) at 296 K, using a ω scan mode with an increment of 0.3°. Preliminary unit cell parameters were obtained from 45 frames. Final unit cell parameters were derived by global refinements of reflections obtained from integration of all the frame data. The collected frames were integrated using the preliminary cell-orientation matrix. The SHELXL software was used for space group and structure determination, refinements, graphics, and structure reporting^[17]. There are some large residual peak in complex 2, and it is normal for the rare earth complexes. The crystallographic data and structural refinement parameters are provided in Table 1. Selected bond lengths and angles of complexes 1 and 2 are listed in Table 2.

Table 1

Table 1. Crystallographic data for complexes 1 and 2

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	1·DMF	[Dy₂L₃(H₂O)]₄-3DMF-7H₂O
Formula	C₆₉H₆₃NuO₁₄Tb₂	C₂₇₃H₂₅₉Dy₈N₂₇O₆₂
Formula weight	1 532.09	6 210.06
Crystal system	Monoclinic	Monoclinic
Space group	P2₁/c	P2₁/c
a/nm	1.323 20(11)	2.580 4(3)
b/nm	2.766 1(2)	2.769 8(3)
c/nm	1.769 75(15)	1.943 7(2)
β/(°)	105.494 0(10)	91.146(2)
V/nm³	6.242 2(9)	13.889(3)
Z	4	2
F(000)	2 904	5 816
D_c/(Mg·m^-3)	1.550	1.399
μ/mm^-1	2.315	2.196
θ range/(°)	1.759~27.464	1.806~25.353
Reflection collected	66 827	126 678
Independent reflection	14 218 (R_int=0.041 2)	25 346 (R_int=0.059 6)
Parameter	791	1 595
R₁ [I > 2σ(I)]	0.033 1	0.050 0
wR₂ [I > 2σ(I)]	0.144 1	0.162 5
Goodness of fit	1.148	0.990

Table 2

Table 2. Selected bond lengths (nm) and angles (°) for complexes 1 and 2

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1
Tb(1)-O(3)	0.223 2(3)	Tb(1)-N(3D)	0.256 1(4)	Tb(2)-O(8)	0.235 4(3)
Tb(1)-O(2)	0.232 4(3)	Tb(1)-N(5H)	0.258 2(4)	Tb(2)-N(7O)	0.246 6(4)
Tb(1)-O(8)	0.233 2(3)	Tb(1)-Tb(2)	0.385 47(4)	Tb(2)-N(2C)	0.249 4(4)
Tb(1)-O(6)	0.236 5(3)	Tb(2)-O(4)	0.222 1(3)	Tb(2)-O(7)	0.249 0(4)
Tb(1)-N(6L)	0.250 9(4)	Tb(2)-O(5)	0.222 4(3)
Tb(1)N(4F)	0.253 4(4)	Tb(2)-O(6)	0.233 1(3)
O(3)-Tb(1)-O(2)	89.01(12)	O(2)-Tb(1)-N(6L)	72.97(13)	N(6L)-Tb(1)-N(4F)	63.06(13)
O(3)-Tb(1)-O(8)	83.07(11)	O(8)-Tb(1)-N(6L)	151.72(12)	O(3)-Tb(1)-N(3D)	79.13(13)
O(2)-Tb(1)-O(8)	86.57(11)	O(6)-Tb(1)-N(6L)	86.22(11)	O(2)-Tb(1)-N(3D)	155.27(13)
O(3)-Tb(1)-O(6)	148.27(12)	O(3)-Tb(1)-N(4F)	72.49(13)	O(8)-Tb(1)-N(3D)	70.62(13)
O(2)-Tb(1)-O(6)	74.50(11)	O(2)-Tb(1)-N(4F)	116.63(12))	O(6)-Tb(1)-N(3D)	104.80(12)
O(8)-Tb(1)-O(6))	69.29(11)	O(8)-Tb(1)-N(4F)	145.21(12)
O(3)-Tb(1)-N(6L)	115.09(12)	O(6)-Tb(1)-N(4F)	139.14(12)
2
Dy(1)-O(18)	0.220 7(5)	Dy(1)-Dy(2)	0.384 37(6)	Dy(2)-O(16)	0.235 2(4)
Dy(1)-O(19)	0.219 1(5)	N(1)-Dy(4)	0.252 7(6)	Dy(2)-N(7)	0.248 5(6)
Dy(1)-O(16)	0.233 8(4)	O(1)-Dy(4)	0.234 2(5)	Dy(2)-N(9)	0.252 4(5)
Dy(1)-O(15)	0.236 6(4)	O(1)-Dy(3)	0.237 5(4)	Dy(2)-N(8)	0.252 4(6)
Dy(1)-O(25)	0.239 8(5)	Dy(2)-O(14)	0.222 1(4)	Dy(2)-N(10)	0.254 4(5)
Dy(1)-N(11)	0.245 4(6)	Dy(2)-O(13)	0.229 5(5)
Dy(1)-N(12)	0.247 5(5)	Dy(2)-O(15)	0.232 6(4)
O(18)-Dy(1)-O(19)	92.2(2)	O(18)-Dy(1)-O(25)	89.99(19)	O(16)-Dy(1)-N(11)	103.18(19)
O(18)-Dy(1)-O(16)	160.15(17)	O(19)-Dy(1)-O(25)	80.87(18)	O(15)-Dy(1)-N(11)	81.05(18)
O(19)-Dy(1)-O(16)	105.15(19)	O(16)-Dy(1)-O(25)	83.42(17)	O(25)-Dy(1)-N(11)	151.19(19)
O(18)-Dy(1)-O(15)	90.64(17)	O(15)-Dy(1)-O(25)	75.03(17)	O(18)-Dy(1)-N(12)	117.28(19)
O(19)-Dy(1)-O(15)	155.73(18)	O(18)-Dy(1)-N(11)	74.3(2)
O(16)-Dy(1)-O(15)	69.59(15)	O(19)-Dy(1)-N(11)	122.9(2)

CCDC: 1818315 1; 1818316, 2.

2. Results and discussion

2.1 Structure description

Complexes 1 and 2 crystallize in the monoclinic system with the similar structure. Herein, the molecular structure of complex 2 is described in detail as a representative example. As shown in Fig. 1b, complex 2 is a triple-decker sandwich structure containing three Schiff base ligands, two Dy(Ⅲ) ions and one water molecule. One Dy(Ⅲ) ion is eight-coordinated and bridges two neighboring Schiff base ligands by four O atoms and four N atoms, while the other one is seven-coordinated by N₂O₂ cavity of one outer Schiff base ligand, two oxygen atoms of the inner common Schiff base ligand, and one oxygen atom of additional water molecule. The average bond distances of Dy1-O and Dy1-N are 0.229 8 and 0.251 2 nm, respectively, which are similar to the corresponding distances of the reference reported^[16]. The average distances between Dy and the N₂O₂ planes are 0.133 nm, which is almost consist with the reference^[16]. The separation between the two intramolecular Dy(Ⅲ) ions amounts to 0.385 5 nm for 2, while the separation is 0.383 9 nm for 1, indicating the presence of intramol-ecular interionic magnetic interaction in terms of the metal-metal separation, which is almost consist with the similar complex reported^[16].

Figure 1

Figure 1. Molecular structures of 1 (a) and 2 (b)

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2.3 Thermal stability

Thermal stability is an important aspect for the application of coordination complex. Thermogravi-metric analysis (TGA) experiments were carried out to determine the thermal stabilities of 1 and 2 (Fig. 2). For complex 1, there are solvent molecules including DMF molecules and water molecules coordinated in the structure, and TG curve showing the first consecutive step of weight loss was observed in the range of 40~200 ℃, corresponding to the release of solvent molecules. Then, the continuously weight loss corresponds to the release of ligands (in the range of 180~800 ℃). For 2, TG curve showing the first consecutive step of weight loss was observed in the range of 40~200 ℃, corresponding to the release of solvent molecules. Then, the continuously weight loss corresponds to the release of ligands in the range of 300~600 ℃.

Figure 2

Figure 2. TG curves of complexes 1 and 2

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2.4 Magnetic studies

The variable-temperature dc magnetic suscepti-bility measurement for complexes 1 and 2 were performed in the temperature range of 2~300 K under an applied magnetic field of 1 000 Oe. The collected data are plotted as χ_MT vs T in Fig. 3. The χ_MT values of 1 and 2 are 24.15 and 28.06 cm³·K·mol^-1 at 300 K, respectively, which are consistent with the expected values of 23.64 cm³·K·mol^-1 for two Tb(Ⅲ) ions (⁷F₆, S=3, L=3, g=4/3)^[18] and 28.34 cm³·K·mol^-1 for two Dy(Ⅲ) ions (⁶H_15/2, S=5/2, L=5, g=4/3)^[19]. With the temperature decreasing, the χ_MT value of 1 almost keeps a constant until 50 K, and then drops rapidly to 8.62 cm³·K·mol^-1 at 2 K, and the χ_MT value of 2 decreases rapidly to 14.36 cm³·K·mol^-1 from 10 to 2 K, which is mostly due to the thermal depopulation of the Stark sublevels and/or significant magnetic aniso-tropy in Tb³⁺/Dy³⁺ ion systems. Compared to the comp-lexes with similar structure without the radical contri-bution^[20-21], it indicates the presence of antiferroma-gnetic coupling between the two Tb/Dy ions for 1 and 2, respectively.

Figure 3

Figure 3. Temperature (T) dependence of χ_MT for 1 (A) and 2 (B) at 1 000 Oe

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In addition, the magnetic-field-dependent magnetic properties of 1 and 2 have been studied. As shown in Fig. 4, three observed non-superposition curves for 1 and 2 display a rapid increase at low field and eventually achieve the maximum value of 11.02μB~11.17μB for 1 and 13.90μB~13.91μB for 2 at 4 T, without reaching the theoretical magnetization saturation(18μB for two Tb(Ⅲ) (⁷F₆, S=3, L=3, g=3/2) ions and 20μB for two Dy(Ⅲ) (⁶H_15/2, S=5/2, L=5, g=4/3) ions, respectively), revealing the crystal-field effect on the Dy(Ⅲ) and Tb(Ⅲ) ions in the two triple-decker complexes.

Figure 4

Figure 4. Plots of M vs H/T for 1 (A) and 2 (B) at different temperatures

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To explore the dynamic magnetic property of the complexes, the temperature dependence of the alternating-current (ac) magnetic susceptibility of 1 and 2 under a zero direct-current (dc) magnetic field oscillating at 10~997 Hz is recorded in Fig. 5~6. As can be seen, 1 and 2 exhibit the frequency-dependent character in the out-of -phase (χ″) signals, indicating the slow relaxation of magnetization, which is generally attributed to the SMM nature of the two complexes. However, the frequency-dependent behavior was not observed in the in-phase (χ′) signals for 1 and 2. Furthermore, the peak was not observed in out-of-phase (χ″) signals for 1 and 2, which suggests the strong effect of quantum tunneling of magnetization (QTM).

Figure 5

Figure 5. Plots for temperature dependence of the in-phase (χ′) (A) and out-of-phase (χ″) (B) ac susceptibility of 1 under zero applied dc magnetic field

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Figure 6

Figure 6. Plots for temperature dependence of the in-phase (χ′) (A) and out-of-phase (χ″) (B) ac susceptibility of 2 under zero applied dc magnetic field

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To reduce the effect of QTM, an optimal direct-current field of 2 000 Oe was applied to the dynamic measurement over 1 and 2. As expected, the frequency-dependent character is still exist in both of the in-phase (χ′) and out-of-phase (χ″) signals for 1 and 2, further confirming the SMM nature of the two complexes, as shown in Fig. 7. In addition, the peak of the out-of-phase signal (χ″) for 2 could be observed until a frequency as low as 10 Hz, indicating the effective suppression of quantum tunneling of magnetization (QTM) under an applied 2 000 Oe magnetic field. On the basis of a thermally activated mechanism, τ=τ₀exp[U_eff/(kT)] and τ=1/(2πν), the Arrhenius law fitting for the data under a 2 000 Oe magnetic field was carried out. As shown in Fig. 8, a linear relationship exists between lnτ and 1/T in the temperature range of 2.7~3.8 K for 2, which in turn result in a barrier U_eff=35.5 cm^-1 (51.0 K) and τ₀=2.7×10^-10 s with R=0.98. However, the relaxation time and energy barrier of slow magnetic relaxation cannot be deduced for 1, most probably because of the stronger tunneling effect of complex 1 in comparison with 2.

Figure 7

Figure 7. Plots for temperature dependence of the in-phase (χ′) and out-of-phase (χ″) ac susceptibility of 1 (A, B) and 2 (C, D) under 2 000 Oe applied dc magnetic field

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Figure 8

Figure 8. Plot of lnτ vs 1/T for 2 under 2 000 Oe applied dc field

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3. Conclusions

In summary, two new complexes [M₂L₃(H₂O)] (M=Tb (1), Dy (2)) with Schiff-base ligands were synthes-ized and characterized by single crystal X-ray diffraction analysis. The structure analysis suggests the present of the magnetic interaction between lanthanide ions. The investigation of magnetic studies confirms the antiferromagnetic interactions between Ln ions. The frequency-dependent out-of-phase signals (χ″) demonstrated the SMM nature of 1 and 2. We hope that the result is helpful for the study of the magnetic properties of multinuclear lanthanide based SMMs.

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Figure 1 Molecular structures of 1 (a) and 2 (b)

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Figure 2 TG curves of complexes 1 and 2

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Figure 3 Temperature (T) dependence of χ_MT for 1 (A) and 2 (B) at 1 000 Oe

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Figure 4 Plots of M vs H/T for 1 (A) and 2 (B) at different temperatures

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Figure 5 Plots for temperature dependence of the in-phase (χ′) (A) and out-of-phase (χ″) (B) ac susceptibility of 1 under zero applied dc magnetic field

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Figure 6 Plots for temperature dependence of the in-phase (χ′) (A) and out-of-phase (χ″) (B) ac susceptibility of 2 under zero applied dc magnetic field

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Figure 7 Plots for temperature dependence of the in-phase (χ′) and out-of-phase (χ″) ac susceptibility of 1 (A, B) and 2 (C, D) under 2 000 Oe applied dc magnetic field

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Figure 8 Plot of lnτ vs 1/T for 2 under 2 000 Oe applied dc field

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Table 1. Crystallographic data for complexes 1 and 2

	1·DMF	[Dy₂L₃(H₂O)]₄-3DMF-7H₂O
Formula	C₆₉H₆₃NuO₁₄Tb₂	C₂₇₃H₂₅₉Dy₈N₂₇O₆₂
Formula weight	1 532.09	6 210.06
Crystal system	Monoclinic	Monoclinic
Space group	P2₁/c	P2₁/c
a/nm	1.323 20(11)	2.580 4(3)
b/nm	2.766 1(2)	2.769 8(3)
c/nm	1.769 75(15)	1.943 7(2)
β/(°)	105.494 0(10)	91.146(2)
V/nm³	6.242 2(9)	13.889(3)
Z	4	2
F(000)	2 904	5 816
D_c/(Mg·m^-3)	1.550	1.399
μ/mm^-1	2.315	2.196
θ range/(°)	1.759~27.464	1.806~25.353
Reflection collected	66 827	126 678
Independent reflection	14 218 (R_int=0.041 2)	25 346 (R_int=0.059 6)
Parameter	791	1 595
R₁ [I > 2σ(I)]	0.033 1	0.050 0
wR₂ [I > 2σ(I)]	0.144 1	0.162 5
Goodness of fit	1.148	0.990

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Table 2. Selected bond lengths (nm) and angles (°) for complexes 1 and 2

1
Tb(1)-O(3)	0.223 2(3)	Tb(1)-N(3D)	0.256 1(4)	Tb(2)-O(8)	0.235 4(3)
Tb(1)-O(2)	0.232 4(3)	Tb(1)-N(5H)	0.258 2(4)	Tb(2)-N(7O)	0.246 6(4)
Tb(1)-O(8)	0.233 2(3)	Tb(1)-Tb(2)	0.385 47(4)	Tb(2)-N(2C)	0.249 4(4)
Tb(1)-O(6)	0.236 5(3)	Tb(2)-O(4)	0.222 1(3)	Tb(2)-O(7)	0.249 0(4)
Tb(1)-N(6L)	0.250 9(4)	Tb(2)-O(5)	0.222 4(3)
Tb(1)N(4F)	0.253 4(4)	Tb(2)-O(6)	0.233 1(3)
O(3)-Tb(1)-O(2)	89.01(12)	O(2)-Tb(1)-N(6L)	72.97(13)	N(6L)-Tb(1)-N(4F)	63.06(13)
O(3)-Tb(1)-O(8)	83.07(11)	O(8)-Tb(1)-N(6L)	151.72(12)	O(3)-Tb(1)-N(3D)	79.13(13)
O(2)-Tb(1)-O(8)	86.57(11)	O(6)-Tb(1)-N(6L)	86.22(11)	O(2)-Tb(1)-N(3D)	155.27(13)
O(3)-Tb(1)-O(6)	148.27(12)	O(3)-Tb(1)-N(4F)	72.49(13)	O(8)-Tb(1)-N(3D)	70.62(13)
O(2)-Tb(1)-O(6)	74.50(11)	O(2)-Tb(1)-N(4F)	116.63(12))	O(6)-Tb(1)-N(3D)	104.80(12)
O(8)-Tb(1)-O(6))	69.29(11)	O(8)-Tb(1)-N(4F)	145.21(12)
O(3)-Tb(1)-N(6L)	115.09(12)	O(6)-Tb(1)-N(4F)	139.14(12)
2
Dy(1)-O(18)	0.220 7(5)	Dy(1)-Dy(2)	0.384 37(6)	Dy(2)-O(16)	0.235 2(4)
Dy(1)-O(19)	0.219 1(5)	N(1)-Dy(4)	0.252 7(6)	Dy(2)-N(7)	0.248 5(6)
Dy(1)-O(16)	0.233 8(4)	O(1)-Dy(4)	0.234 2(5)	Dy(2)-N(9)	0.252 4(5)
Dy(1)-O(15)	0.236 6(4)	O(1)-Dy(3)	0.237 5(4)	Dy(2)-N(8)	0.252 4(6)
Dy(1)-O(25)	0.239 8(5)	Dy(2)-O(14)	0.222 1(4)	Dy(2)-N(10)	0.254 4(5)
Dy(1)-N(11)	0.245 4(6)	Dy(2)-O(13)	0.229 5(5)
Dy(1)-N(12)	0.247 5(5)	Dy(2)-O(15)	0.232 6(4)
O(18)-Dy(1)-O(19)	92.2(2)	O(18)-Dy(1)-O(25)	89.99(19)	O(16)-Dy(1)-N(11)	103.18(19)
O(18)-Dy(1)-O(16)	160.15(17)	O(19)-Dy(1)-O(25)	80.87(18)	O(15)-Dy(1)-N(11)	81.05(18)
O(19)-Dy(1)-O(16)	105.15(19)	O(16)-Dy(1)-O(25)	83.42(17)	O(25)-Dy(1)-N(11)	151.19(19)
O(18)-Dy(1)-O(15)	90.64(17)	O(15)-Dy(1)-O(25)	75.03(17)	O(18)-Dy(1)-N(12)	117.28(19)
O(19)-Dy(1)-O(15)	155.73(18)	O(18)-Dy(1)-N(11)	74.3(2)
O(16)-Dy(1)-O(15)	69.59(15)	O(19)-Dy(1)-N(11)	122.9(2)

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沈阳化工大学材料科学与工程学院沈阳 110142

席夫碱类三明治型铽/镝金属配合物的合成、表征及磁性

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