КООРДИНАЦИОННАЯ ХИМИЯ, 2014, том 40, № 4, с. 251-256
УДК 541.49
SYNTHESIS, CRYSTAL STRUCTURE, AND PROPERTIES OF A NEW LANTHANIDE TARTRATE COORDINATION POLYMER
© 2014 W. Xu, H. S. Chang, W. Liu, and Y. Q. Zheng*
Center of Applied Solid State Chemistry Research Ningbo University, Ningbo, 315211 P.R. China
*E-mail: yqzhengmc@163.com Received January 1, 2013
A new coordination polymer of terbium tartrate [Tb(H2O)3(C4H5O6)(C4H4O6)] has been synthesized and crystallizes in the polar space group P4i with cell constants a = 6.0415(9), b = 6.0415(9), c = 36.516(7) A, V = 1332.8(4) A3, Z = 4. The terbium(III) ion of title complex is nine-coordinate through oxygen donors. Four different coordination modes of tartrate occur. This Tb(III) complex exhibits a characteristic luminescence in the visible region upon excitation at 353 nm. The temperature-dependent magnetic properties of the Tb(III) complex were investigated in the temperature range of2—300 K. Title compound exhibits significant ferroelectric properties at room temperature (remnant polarization 2Pr = 0.160 цС cm-2, coercive field 2Ec = 44.5 kV cm-1, saturation of the spontaneous polarization Ps = 0.176 цС cm-2).
DOI: 10.7868/S0132344X14030104
INTRODUCTON
Compounds of several tartrates have very interesting physical properties including ferroelectricity, piezoelectricity and optical second harmonic generation [1—7]. Consequently, they are used in transducers and several linear and nonlinear mechanical devices. This has led many investigators to grow single crystals of tartrate compounds and study their characteristics [811]. The rare earth metals have many important properties such as exhibiting a high coordination number, strong magnetism, fluorescence, neutron aborption and catalysis [12—14]. The design and synthesis of lanthanide tartrates have attracted many of workers interesting. Although single crystal X-ray structure analyses of several lanthanide tartrates have been reported, almost all of the reports were focused on the syntheses and crystal structures, the information on physico-chemical properties of lanthanide tartrate is limited. Magnetic properties of gadolinium tartrates [15] were discussed by Chaudhuri and co-workers. Nitrogen adsorption behaviors were observed lanthanum tartrate, cerium tartrate and praseodymium tartrate [16]. Lanthanide tartrates include europium, terbium, and dysprosium [17] have investigated luminescent properties.
In this paper, a terbium tartrate coordination polymer [Tb(H2O)3(C4H5O6)(C4H4O6)] (I) has been obtained by reaction of tartaric acid and terbium chloride. X-ray crystallographic analysis reveals that it belongs P41 space group, also indicates space group by powder X-ray diffraction. Low-temperature magnetic susceptibility measurements show weak antiferromag-netic interaction between the terbium ions. What's
more, here exists an electric hysteresis loop that is a typical ferroelectric feature.
EXPERIMENTAL
Materials and physical methods. All chemicals of reagent grade were commercially available and used without further purification. Powder X-ray diffraction measurements were carried out with a Bruker D8 Focus X-ray diffractometer to check the phase purity. Single-crystal X-ray diffraction data were collected on a Rigaku R-Axis Rapid X-ray diffractometer. The C, H, and N microanalyses were performed with a PE 2400II CHNS elemental analyzer. The FT-IR spectrum was recorded from KBr pellets in the range 4000-400 cm-1 on a Shimadzu FTIR-8900 spectrometer. Fluorescence emission spectra were recorded in the solid state on HITACHI F-4600 fluorescence spectrophotometer. The temperature-dependent magnetic susceptibility was determined with a Quantum Design SQUID magnetomer (Quantum Design Model MPMS-7) in the temperature range 2-300 K with an applied field of 5 kOe. The ferroelectric property of the solid-state sample was measured by a pellet of powdered sample using a Premier station ferroelectric tester at room temperature while the sample was immerged in insulating oil.
Synthesis of I. The pH of a mixture of TbCl3 prepared from Tb4O7 (0.149 g, 0.2 mmol) dissolved in 5 mL diluted HCl and L-(+)-tartaric acid (0.06 g, 0.4 mmol) in 30 mL H2O was adjusted to 2.65 with diluted HCl under stirring. Colorless crystals of the title compound were obtained after 2 days at a temperature of 45°C.
Table 1. Crystallographic data and refinement details for I
Parameter Value
Formula weight 510.12
Crystal habit; color Block; colorless
Crystal system Tetragonal
Space group P41
T, K 293(2)
a, A 6.0415(9)
c, A 36.516(7)
Volume, A 1332.8(4)
Z 4
P calcd g cm-3 2.542
mm-1 5.399
F(000) 992
9 Range for data collection, deg 3.37-27.46
Reflections collected 12831
Independent reflections (Rjnt) 3041 (0.0504)
Reflection with I > 2ct(T) 2861
Number of parameters 217
Goodness-of-fit on F 2 1.194
Final R indices (I > 2ct(I)) 0.0276, 0.0300
R indices (all data) 0.0642, 0.0650
Largest difference peak and hole, e A-3 0.900, -1.482
The yield was 154.7 mg (54.6%) based on the initial Tb4O7 input.
For C8H15O15Tb anal. calcd., %: Found, %:
C, 18.82; C, 18.76;
O(14)
H, 2.94. H, 3.02.
Tb#4
Fig. 1. ORTEP view of the polymer of complex I. The displacement ellipsoids are drawn at 45% probability level, hydrogen atoms are omitted for clarity.
IR (KBr; v, cm-1): 3261 m, 2665 m, 1718 s, 1585 v.s, 1401 s, 1140 s, 1068 s, 941 w, 832 w, 791 m, 682 m, 571 w.
X-ray crystallography. A suitable single crystal of I was selected under a polarization microscope and fixed with epoxy cement on a fine glass fiber which was then mounted on a Rigaku R-Axis Rapid IP X-ray dif-fractometer, operating with graphite-monochromated Mo^a radiation (X = 0.71073 A) for cell determination and subsequent data collection. The data were corrected for Lp and empirical absorption effects. The SHELXS-97 and SHELXL-97 programs were used for structure solution and refinement [18]. The structure was solved by using direct methods. Subsequent difference Fourier syntheses enabled all non-hydrogen atoms to be located. After several refinement cycles, the hydrogen atoms associated with carbon atoms were geometrically generated, and the remainder of the hydrogen atoms were located from successive difference Fourier syntheses. Finally, all non-hydrogen atoms were refined with anisotropic displacement parameters by a full-matrix least-squares technique, and hydrogen atoms with isotropic displacement parameters were set to 1.2 times the values for the associated heavier atoms. Detailed information about the crystal data and structure determination is summarized in Table 1. Selected interatomic distances and bond angles are listed in Table 2.
RESULTS AND DISCUSSION
Compound (Fig. 1) comprises 2D chiral sheets built up by connecting Tb3+ ions with bridging syn-anti carboxylate groups of tartrates. Each Tb3+ ion is nine-coordinate from three oxygens from three waters and six oxygens from four tartates in a tricapped trigonal prism coordination geometry. The bond lengths of Tb-O are in the range of2.323(5)-2.702(11) A (Table 2). For the tartrate ligand, each one bridges two Tb3+ ions through "1,2-chelation" involving a carboxylate oxygen and the ortho-hydroxy with five-membered rings. The carboxylate group O(1) atom and the hydroxyl O(3) atom chelate a Tb atom. Atom O(2) bridges to a aymmetry-related Tb atom, forming a 1D chain along [100] (Fig. 2). In the same way, O(7) and O(9) chelate Tb atom, O(8) bridges another Tb atom between chains, generating 2D layer parallel to the plane (001) (Fig. 3). The layers are linked together through a complicated hydrogen-bonding scheme involving the water ligands, hydroxyl O atoms and the carboxylate O atoms. Thus, a three-dimensional framework is produced (Fig. 4).
Single crystal XRD results also confirm that the material grown in the present investigation is similar to samarium tartrate trihydrate [19], erbium ditartrate trihydrate [20]. Due to complex I is terbium(III) ditar-trate trihydrate [Tb(H2O)3(C4H5O6)(C4H4O6)], and asymmetric unit contains two absolute independence two tartrate of one tartrate anion and one hydrogen-
Table 2. Selected bond lengths (A) and bond angles (deg) for I*
Bond d, A Bond d, A Bond d, A
Tb-O(1) 2.333(5) Tb-O(7) 2.323(5) Tb-O(13) 2.396(7)
Tb-O(2)#1 2.344(5) Tb-O(8)#2 2.344(5) Tb-O(14) 2.702(11)
Tb-O(3) 2.503(11) Tb-O(9) 2.522(12) Tb-O(15) 2.420(7)
Angle ro, deg Angle ro, deg Angle ro, deg
O(1)TbO(2)#1 133.7(2) O(2)#1rTbO(13) 80.6(2) O(7)TbO(14) 137.0(3)
O(1)TbO(3) 63.7(2) O(2)#1TbO(14) 69.0(3) O(7)TbO(15) 85.8(2)
O(1)TbO(7) 85.2(2) O(2)#1rTbO(15) 77.9(2) O(8)#2TbO(9) 70.3(2)
O(1)TbO(8)#2 81.9(2) O(3)TbO(7) 73.7(2) O(8)#2TbO(13) 77.5(2)
O(1)TbO(9) 73.5(2) O(3)TbO(8)#2 134.9(2) O(8)#2TbO(14) 67.3(3)
O(1)TbO(13) 86.0(2) O(3)TbO(9) 121.0(1) O(8)#2TbO(15) 80.4(2)
O(1)TbO(14) 137.8(3) O(3)TbO(13) 72.2(3) O(9)TbO(13) 143.7(2)
O(1)TbO(15) 144.9(2) O(3)TbO(14) 120.7(4) O(9)TbO(14) 118.3(4)
O(2)#1TbO(3) 70.0(2) O(3)TbO(15) 143.9(2) O(9)TbO(15) 72.1(3)
O(2)#1TbO(7) 81.4(2) O(7)TbO(8)#2 134.1(2) O(13)TbO(14) 60.4(4)
O(2)#1TbO(8)#2 136.3(2) O(7)TbO(9) 63.7(2) O(13)TbO(15) 118.9(2)
O(2)#1TbO(9) 134.9(2) O(7)TbO(13) 145.2(2) O(14)TbO(15) 58.5(4)
O H-O Distances, A O-H—O angle, deg
H-O O—H O-O
O(3)-H(35)-O(11)#3 0.86 1.81 2.663(9) 171
O(4)-H(45)-O(12)#4 0.89 2.00 2.857(9) 164
O(6)-H(6)-O(15)#5 0.83 1.81 2.622(9) 168
O(9)-H(95)-O(5)#6 0.86 1.81 2.662(9) 174
O(10)-H(105)-O(6)#7 0.85 2.09 2.863(9) 151
O(13)-H(13^)-O(7)#2 0.86 1.89 2.718(8) 161
O(13)-H(135)-O(4)#2 0.86 1.94 2.771(9) 165
O(14)-H(14^)-O(4)#8 0.85 2.14 2.950(9) 159
O(14)-H(145)-O(10)#8 0.85 2.05 2.855(9) 158
O(15)-H(15^)-O(10)#! 0.84 1.98 2.764(8) 154
O(15)-H(155)-O(1)#1 0.85 1.91 2.708(8) 156
Symmetry transformations used to generate equivalent atoms: #1 x,y #5 y, -x + 1, z - 1/4; #6 -y + 1, x, z + 1/4; #7 -y, x - 1, z + 1/4; #8x
' + 1, z; #2 x + 1, y, z; #3 y + 1, -x + 1, z - 1/4; #4 y, -x, z - 1/4; 5 x + 1, y + 1
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