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Synthesis and structural characterization of a novel two-dimensional 3d-4f heterometallic coordination framework based on pentanuclear lanthanide cluster
Solid State Sciences 14 (2012) 445e450
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Synthesis and structural characterization of a novel two-dimensional 3d-4f heterometallic coordination framework based on pentanuclear lanthanide cluster Guo-Ming Wang a, *, Jin-Hua Li a, Zeng-Xin Li a, Pei Wang a, Ying-Xia Wang b, Jian-Hua Lin b a b
Teachers College, College of Chemistry, Chemical Engineering and Environment of Qingdao University, Shandong 266071, China Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
a r t i c l e i n f o
a b s t r a c t
Article history: Received 22 July 2011 Received in revised form 13 December 2011 Accepted 23 January 2012 Available online 30 January 2012
A novel 3d-4f heterometallic coordination polymer, {[Tm5(m3-OH)2(BDC)6(IN)2Cu(H2O)2]$(H2O)3}n (1) [BDC ¼ benzene-1,2-dicarboxylate, IN ¼ isonicotinate], has been hydrothermally synthesized and structurally characterized by single crystal X-ray diffraction, FTIR, elemental analysis, powder X-ray diffraction and thermogravimetric analysis. The compound crystallizes in monoclinic system, space group P21/c (No. 14), a ¼ 13.7302(5) Å, b ¼ 23.5428(3) Å, c ¼ 21.5789(2) Å, b ¼ 91.491(3) , V ¼ 6973.0(3) Å3, and Z ¼ 4. The structure exhibits unusual two-dimensional Tm-carboxylate layer, which is constructed from the expansion of novel pentanuclear {Tm5} clusters. More interestingly, the heterometallic Cu(I) ions were successfully planted into such Ln-carboxylate layer by the bifunctional IN bridging ligands, resulting in the formation of an unprecedented 2D heterometallic lanthanide-transition-metal framework. Ó 2012 Elsevier Masson SAS. All rights reserved.
Keywords: Hydrothermal synthesis Coordination polymer Crystal structure Isonicotinic acid 1,2-benzenedicarboxylic acid TmeCu heterometallic complex
1. Introduction Design and construction of metal-organic frameworks (MOFs) have attracted extensive interest over the last decades due to their intriguing variety of architectures and structural topologies, as well as their potential applications in catalysis, gas storage and separation, guest exchange, magnetism and luminescence, etc [1e9]. Intelligent ligand design or selection and appropriate choice of the metal centers with suitable coordination geometries are usually the main keys to the construction of such coordination polymers. In this context, a large number of homometallic MOFs possessing either d-block transition-metal (TM) or f-block lanthanide (Ln) ions have been obtained by conventional solution syntheses or hydrothermal techniques [10e16]. By contrast, the progress of the analogous chemistry of heterometallic Ln-TM compounds still remains less developed [17e26]. This is not only because of the high, variable coordination numbers and versatile coordination geometry characteristics of the Ln ions, but also due to the different competitive reactions between the Ln and TM ions and the organic ligands. Fortunately, the Ln and TM ions have different affinities for O- and N-donors, which thus provide high likelihood for construction of unusual heterometallic Ln-TM architectures by choosing * Corresponding author. Tel./fax: þ86 532 85956024. E-mail address: [email protected] (G.-M. Wang). 1293-2558/$ e see front matter Ó 2012 Elsevier Masson SAS. All rights reserved. doi:10.1016/j.solidstatesciences.2012.01.018
multifunctional ligands with both O and N donors. Isonicotinic acid (HIN), for example, is such a potential bifunctional ligand and widely used to construct new hetero-Ln-TM frameworks, in which the carboxylate group is likely to coordinate to hard lanthanide ions and the relatively softer nitrogen atom favors to bind to soft transitionmetal ions such as Ag(I) or Cu(I) [27e35]. This prompted us to choose it as an effective bridging ligand in constructing new hetero-Ln-TM compounds. On the other hand, high-nuclear lanthanide cluster entities as secondary building units (SBUs) have been proved as an effective and powerful synthetic strategy in constructing new MOFs [36]. Therefore, another complementary organic ligand with dicarboxylate groups, i.e. 1,2-benzenedicarboxylic acid (H2BDC), is intentionally introduced and believed to be an ideal candidate to incorporate more lanthanide centers into one cluster. Certainly, synthesizing complexes with mixed IN and BDC ligands is also a challenge due to the competitive coordination. Fortunately, as a result of our attempts such a hetero-Ln-TM compound, {[Tm5(m3-OH)2(BDC)6(IN)2Cu(H2O)2]$(H2O)3}n (1) was obtained from spontaneous assembly of mixed metal ions and ligands under hydrothermal conditions. Indeed, our results show that the lanthanide Tm(III) ions can be held together by BDC ligands to form novel pentanuclear {Tm5} cluster, which themselves are further interconnected to form a 2D architecture. The hetero-copper(I) centers, as expected, are successfully introduced by the bifunctional IN ligands to form an unprecedented hetero-Ln-TM MOFs.
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G.-M. Wang et al. / Solid State Sciences 14 (2012) 445e450 Table 2 Selected bond length (Å) for 1.a
Fig. 1. Experimental and simulated X-ray powder diffraction pattern of complex 1.
2.1. Synthesis The title compound was synthesized under mild hydrothermal conditions. Typically, a mixture of Tm2O3 (0.191 g, 0.5 mmol), HIN (0.193 g,1.6 mmol), H2BDC (0.170 g,1.0 mmol), Cu(NO3)2$3H2O(0.055 g, 0.25 mmol) and H2O (10 ml) was stirred at room temperature. The mixture was sealed in a Teflon-lined autoclave and heated at 170 C for 6 days and then cooled to room temperature. Yellow prism-like crystals was recovered by filtration, washed with distilled water, and dried in air (62% yield based on Tm). Attempts to make other isomorphous compouns with other Ln ions like Tb, Dy, Er and Yb, under the same condition were fruitless. Anal. Found: C, 31.78; H, 2.04; N, 1.18%. Calcd: C, 31.86; H, 1.96; N, 1.24%. IR (KBr pellet, cm1): 3446 m, 1632 s, 1586 s, 1543 s, 1496 w, 1412 s, 1249 w, 1158 w, 1140 w, 1090 w, 1061 w, 876 w, 828 w, 773 m, 684 m, 649 w, 443 w. Table 1 Crystal data and structure refinement for 1.
Reflection collected/unique Completeness to q ¼ 26.49 Absorption correction Refinement method Goodness-of-fit on F2 Final R1, wR2[I > 2s(I)] R indices (all data) Largest diff. peak and hole (e Å3)
2.525(6) 2.425(6) 2.420(7) 2.340(7) 2.438(6) 2.531(6) 2.254(6) 2.357(6) 2.264(6) 2.265(6) 2.307(6) 2.281(7) 2.429(7) 2.368(6) 2.380(6) 2.338(7) 2.280(6) 2.236(6) 2.224(7) 2.306(6) 2.281(7) 2.262(6) 2.295(6) 2.422(5)
Tm(3)eO(26) Tm(4)eO(8) Tm(4)eO(19) Tm(4)eO(20) Tm(4)eO(21) Tm(4)eO(24) Tm(4)eO(26) Tm(4)eO(27) Tm(4)eO(32) Tm(5)eO(1)#2 Tm(5)eO(11) Tm(5)eO(12) Tm(5)eO(15) Tm(5)eO(16) Tm(5)eO(23) Tm(5)eO(24) Tm(5)eO(26) Tm(5)eO(31) Cu(1)eN(1) Cu(1)eN(2)#3 Tm(2)eTm(3) Tm(3)eTm(4) Tm(4)eTm(5)
2.449(5) 2.279(7) 2.423(6) 2.410(6) 2.265(6) 2.286(6) 2.368(6) 2.340(7) 2.271(6) 2.263(6) 2.397(6) 2.384(6) 2.475(6) 2.451(6) 2.552(6) 2.411(6) 2.362(6) 2.281(7) 1.886(8) 1.893(8) 3.8836(6) 3.8762(6) 3.8091(7)
a Symmetry transformations used to generate equivalent atoms: #1 -xþ2, yþ1/2, -zþ3/2; #2 -xþ1, y-1/2, -zþ3/2; #3 x, y-1, z.
2. Experimental
Empirical formula Formula weight Temperature (K) Wavelength (Å) Crystal system Space group A (Å) b (Å) c (Å) b ( ) V (Å3) Z, Calculated density (g cm3) Absorption coefficient (mm1) F(000) Crystal size (mm) q range for data collection/ Limiting indices
Tm(1)eO(3) Tm(1)eO(4) Tm(1)eO(5) Tm(1)eO(6) Tm(1)eO(17) Tm(1)eO(18) Tm(1)eO(22)#1 Tm(1)eO(25) Tm(1)eO(29) Tm(2)eO(2) Tm(2)eO(4) Tm(2)eO(9) Tm(2)eO(13) Tm(2)eO(14) Tm(2)eO(25) Tm(2)eO(28) Tm(2)eO(30) Tm(3)eO(7) Tm(3)eO(10) Tm(3)eO(14) Tm(3)eO(15) Tm(3)eO(18) Tm(3)eO(20) Tm(3)eO(25)
The X-ray powder diffraction pattern for the bulk product is in good agreement with the pattern based on single-crystal X-ray solution in position, indicating the phase purity of the as-synthesized samples of the title compound (Fig. 1). 2.2. Characterization Infrared spectra were obtained from sample powder pelletized with KBr on an ABB Bomen MB 102 series FTIR spectrophotometer over a range 400e4000 cm1. Powder X-ray diffraction (XRD) data were obtained using a Philips X’Pert-MPD diffractometer with Cu-Ka1 radiation (l ¼ 1.54076 Å). The elemental analysis was carried out on an Elemental Vario EL III CHNOS elemental analyzer. The thermogravimetric analysis (TGA) was performed on a Mettler Toledo TGA/SDTA 851e analyzer in N2 atmosphere with a heating rate of 10 C/min. 2.3. Determination of crystal structure
C60H44CuN2O35Tm5 2261.16 295(2) 0.71073 Monoclinic P21/c 13.7302(5) 23.5428(3) 21.5789(2) 91.491(3) 6973.0(3) 4, 2.154 6.689 4288 0.10 0.10 0.05 1.48e26.00 16 h 16,28 k 29, 26 l 26 54132/13692 [R(int) ¼ 0.1044] 99.9% Semi-empirical from equivalents Full-matrix least-squares on F2 1.084 R1 ¼ 0.0464, wR2 ¼ 0.0736 R1 ¼ 0.0867, wR2 ¼ 0.0776 1.234 and 1.009
A suitable single crystal of as-synthesized compound with the dimensions of 0.10 0.10 0.05 mm3 was carefully selected under
Fig. 2. IR spectrum of 1.
G.-M. Wang et al. / Solid State Sciences 14 (2012) 445e450
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Fig. 3. ORTEP view of the coordination environment of Tm and Cu ions in complex 1 with thermal ellipoids at the 50% probability level. All H atoms are omitted for clarity. Symmetry code: (i) 1-x, 0.5 þ y, 1.5-z; (ii) 2-x, 0.5 þ y, 1.5-z; (iii) x, 1 þ y, z.
an optical microscope and glued to thin glass fiber with epoxy resin. Crystal structure determination by X-ray diffraction was performed on a Siemens SMART CCD diffractometer with graphitemonochromated Mo Ka (l ¼ 0.71073 Å) in the u and f scanning mode at room temperature. An empirical absorption correction was applied using the SADABS program [37]. The structure was solved by direct methods using SHELXS-97 [38]. The heavy atoms were first located, and other non-H atoms were found in the successive Fourier difference maps. The H atoms of organic ligands were geometrically placed and refined using a riding model. However, the H atoms of water molecules have not been included in the final refinement. The structures were refined on F2 by full-matrix leastsquares methods using the SHELXL-97 program package [38]. All non-hydrogen atoms were refined anisotropically. Crystallographic data and selected bond distances for 1 are listed in Tables 1 and 2, respectively. 3. Results and discussion 3.1. Infrared (IR) spectrum The FTIR spectrum of the title compound is shown in Fig. 2. The strong and broad absorption bands at around 3446 cm1 is
assigned to the vibrations of coordinating or noncoordinating water molecules. The strong bands appearing around 1586 and 1412 cm1 are characteristic of the asymmetric and symmetric stretching vibrations of the carboxylate group, respectively. No strong bands ranging from 1690 to 1730 cm1 indicate that all carboxyl groups of organic ligands are deproponated [39]. 3.2. Crystal structure The asymmetric unit of 1 consists of five crystallographically unique Tm(III) ions, one Cu(I) ion, two m3-OH ions, two IN and six BDC2 ions, two coordinated and three noncoordination water molecules. As shown in Fig. 3, atoms Tm(1) and Tm(5) are both nine-coordinate with tricapped trigonal prism configurations and the same coordination environments: one m3-OH, six carboxylate oxygen atoms (OCOO) from three BDC ligands and two coordinated water molecules. Tm(2), Tm(3) and Tm(4) centers, however, are eight-coordinated and have bicapped trigonal prism coordination geometries: one m3-OH, five OCOO from three BDC ligands, one OCOO from one IN ligand and one coordinated water molecule for Tm(2) and Tm(3), respectively; two m3-OH and six OCOO from four BDC ligands for Tm(4). The TmeO bond lengths range from 2.229(6) to 2.531(6) Å. The OeTmeO bond angles are in the range of 51.6
Fig. 4. View of the structure of {Tm5} cluster.
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Fig. 5. View of the structure of 2D lanthanide layer constructed by {Tm5} clusters.
(8)-154.1 (2) . The six BDC ligands are completely deprotonated and exhibit three types of coordination modes (Chart 1aec), simultaneously coordinating three Tm(III) ions in tetra-, pentaand hexadentate chelating-bridging modes, respectively. Both IN ligands, however, adopt the same tridentate bridging mode: the nitrogen atom coordinates to the Cu center and the carboxylate connects to two Tm centers in a bimonodentate fashion (1 d). The Cu atom has a nearly linear configuration defined by two N atoms from two bridging IN ligands. Interestingly, although copper(II) salts were used as starting materials, the Cu center in the product is in the þ1 oxidation state, which may be attributed to a reduction reaction occurring under the hydrothermal conditions used. The CueN distances are typical, varying from 1.885(8) to 1.893(8) Å, and the NeCueN bond angle is 165.6(4) . Five Tm(III) centers, occurring in the same plane, are held together by two m3-OH groups, two IN and six BDC ligands to built up
Chart 1. Coordination modes of BDC and IN ligands in Complex 1.
a novel pentanuclear cluster, [Tm5(m3-OH)2(bdc)6(IN)2(H2O)2] (Fig. 4). In the core, the {Tm5} skeleton can be conceptually regarded as consisting of two identical equilateral triangles, Tm(1)Tm(2) Tm(3) and Tm(3)Tm(4)Tm(5). Each side of the two equilateral triangles has a mean Tm-Tm separation of w3.884 Å, and the angles formed by the three Tm centers are roughly 58.1, 60.1 and 61.8 , respectively. Two m3-OH groups, O(25)H and O(26)H, orientate in the same direction and capped on each triangular face. The distance of the m3-OH unit to the triangular metal face is ca. 1.0 Å. It worthy to note that odd pentanuclear lanthanide cluster is particularly rare [40e45], though a few tetra-, penta-, hexa- hepta-, octa-, nona-, dodeca-, tetradeca- and pentadecanuclear lanthanide clusters have been reported. More importantly, the present {Tm5} cluster in 1 is distinct from the square pyramidal geometry found in other Ln5 clusters, and is firstly observed either in a discrete molecule or as a fragment in a higher nuclearity lanthanide complex. Each {Tm5} cluster is connected in turn to four neighboring {Tm5} groups by four BDC anions in coordination modes 1b to give an interesting 2D lanthanide layer with rhombic cavities along the direction of the c-axis (Fig. 5). Those BDC ligands in modes 1a and 1c, however, are solely responsible for the assembly of the pentanuclear lanthanide cluster, and make no contribution to the expansion of such {Tm5} clusters into 2D network. The rhombus size is ca. 17.44 11.56 Å (defined by the separation between two opposite Tm centers). However, these huge cavities are not empty and occupied by [Cu(IN)2] moieties, which seem like many longspan bridges flying across the cavities. As shown in Fig. 6, besides providing the carboxylate groups (eCOO) to coordinate to the {Tm5} core, the IN ligands are simultaneously responsible to introduce the softer Cu(I) ions into the lanthanide layer through eNeCu(I)eNe coordination bonds. Thus, an unprecedented 2D heterometallic Ln-TM network involving mixed BDC and IN ligands is obtained. It must to be pointed out that, although several 3D 3d4f and 4d-4f heterometallic Ln-TM coordination polymers
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Fig. 6. View of the 2D structure of heterometallic Tm-Cu network.
incorporating IN ligand have been reported recently [21,27e34], the design and construction of 2D 3d-4f heterometallic coordination frameworks still remains undeveloped. Interestingly, if we treated the {Tm5Cu} cluster as the SBUs, complex 1 exhibits a sixconnected network (Fig. 7). A topological analysis of this net was performed with OLEX which gives the short vertex (Schäfli) symbol 364653. Meanwhile, the adjacent 2D layers are packed in an ABAB sequence along the c-axis (Fig. 8). All benzene rings of the BDC ligands are alternately distributed up and down each layer, acting as an organic skin to wrap the neighboring layers into a perfect inorganic-organic sandwich structure.
Fig. 7. The 2D topological network of 1 viewed along the c direction. Yellow balls are the six-connected nodes and represent the {CuTm5} units. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
Fig. 8. The packing of the 2D heterometallic Tm-Cu layers along [001] direction with the ABAB sequence.
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Appendix. Supplementary material Supplementary material associated with this article can be found, in the online version, at doi:10.1016/j.solidstatesciences. 2012.01.018. References [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] Fig. 9. TG curve of 1. [12] [13]
3.3. Thermal property The thermogravimetric analysis (TGA) was performed in dry N2 atmosphere from 30 to 800 C with a heating rate of 10 C/min. As shown in Fig. 9, the lattice-water and the coordinated water molecules were gradually lost in the temperature range 30e280 C (observed: 4.22%; expected: 3.98%). On further heating, a continuous weight loss of 30.02% occurred in the range from 280 to 970 C, corresponding to the decomposition and removal of the organic ligands (observed: 54.58%; expected: 54.95%).
[14] [15] [16] [17] [18] [19] [20] [21] [22] [23]
4. Conclusions In summary, a novel 3d-4f heterometallic coordination polymer with the formula {[Tm5(m3-OH)2(BDC)6(IN)2Cu(H2O)2]$(H2O)3}n (1), had been synthesized and structurally characterized. Its structure contains unprecedented homometallic {Tm5} clusters, which themselves can propagate to give 2D Ln-carboxylate layer with mixed BDC and IN ligands. The heterometallic Cu(I) ions, as expected, were successfully planted into the 2D Ln-carboxylate layer by the bifunctional IN ligands with preferential coordination sites. Besides providing an intriguing example of heterometallic coordination polymer, this work also indicates that it is promising to construct new unusual architectures by using lanthanide-based SBUs. Further studies on this perspective are now under way in our laboratory.
[24] [25] [26] [27] [28] [29] [30] [31] [32] [33] [34] [35] [36] [37] [38]
Acknowledgement We gratefully acknowledge the financial support from the National National Natural Science Foundation of China (No. 20901043), Beijing National Laboratory for Molecular Sciences (BNLMS), the Young Scientist Foundation of Shandong Province (No. BS2009CL041) and the Natural Science Foundation of Shandong Province (No. ZR2009FQ022).
[39] [40] [41] [42] [43] [44] [45]
S. Kitagawa, R. Matsuda, Coord. Chem. Rev. 251 (1997) 2490. S.R. Batten, R. Robson, Angew. Chem. Int. Ed. 37 (1998) 1460. S. Noro, S. Kitagawa, M. Kondo, K. Seki, Angew. Chem. Int. Ed. 39 (2000) 2082. M. Shibasaki, N. Yoshikawa, Chem. Rev. 102 (2002) 2187. J. Kido, Y. Okamoto, Chem. Rev. 102 (2002) 2357. O.M. Yaghi, M. O’Keeffe, N.W. Ockwig, H.K. Chae, M. Eddaoudi, J. Kim, Nature 423 (2003) 705. D. Bradshaw, J.B. Claridge, E.J. Cussen, T.J. Prior, M.J. Rosseinsky, Acc. Chem. Res. 38 (2005) 273. X. Guo, G. Zhu, Z. Li, F. Sun, Z. Yang, S. Qiu, Chem. Commun. 9 (2006) 3172. R. Banerjee, A. Phan, B. Wang, C. Knobler, H. Furukawa, M. O’Keeffe, O.M. Yaghi, Science 319 (2008) 939. G.B. Gardner, D. Venkataraman, J.S. Moore, S. Lee, Nature 374 (1995) 792. O.R. Evans, R. Xiong, Z. Wang, G.K. Wong, W. Lin, Angew. Chem. Int. Ed. 38 (1999) 536. M.H. Zeng, W.X. Zhang, X.Z. Sun, X.M. Chen, Angew. Chem. Int. Ed. 44 (2005) 3079. Q.R. Fang, G.S. Zhu, Z. Jin, M. Xue, X. Wei, D.J. Wang, S.L. Qiu, Angew. Chem. Int. Ed. 45 (2006) 616. M.R. BNrgstein, M.T. Gamer, P.W. Roesky, J. Am. Chem. Soc. 126 (2004) 5213. Y. Wan, L. Zhang, L. Jin, S. Gao, S. Lu, Inorg. Chem. 42 (2003) 4985. Y.Q. Sun, J. Zhang, Y.M. Chen, G.Y. Yang, Angew. Chem. Int. Ed. 44 (2005) 5814. B. Zhao, P. Cheng, X.Y. Chen, C. Cheng, W. Shi, D.Z. Liao, S.P. Yan, Z.H. Jiang, J. Am. Chem. Soc. 126 (2004) 3012. B. Zhao, X.Y. Chen, P. Cheng, D.Z. Liao, S.P. Yan, Z.H. Jiang, J. Am. Chem. Soc. 126 (2004) 15394. B. Zhao, H.L. Gao, X.Y. Chen, P. Cheng, W. Shi, D.Z. Liao, S.P. Yan, Z.H. Jiang, Chem. Eur. J. 12 (2006) 149. X.Q. Zhao, B. Zhao, Y. Ma, W. Shi, P. Cheng, Z.H. Jiang, D.Z. Liao, S.P. Yan, Inorg. Chem. 46 (2007) 5832. J.W. Cheng, S.T. Zheng, G.Y. Yang, Inorg. Chem. 46 (2007) 10534. Y.C. Qiu, H.G. Liu, Y. Ling, H. Deng, R.H. Zeng, G.Y. Zhou, M. Zeller, Inorg. Chem. Commun. 10 (2007) 1399. Z.H. Liu, Y.C. Qiu, Y.H. Li, G. Peng, B. Liu, H. Deng, Inorg. Chem. Commun. 12 (2009) 204. M. Sakamoto, K. Manseki, H. Okawa, Coord. Chem. Rev. 219-221 (2001) 379. C. Benelli, D. Gatteschi, Chem. Rev. 102 (2002) 2369. M. Andruh, J.P. Costes, C. Diaz, S. Gao, Inorg. Chem. 48 (2009) 3342. M.B. Zhang, J. Zhang, S.T. Zheng, G.Y. Yang, Angew. Chem. Int. Ed. 44 (2005) 1385. J.W. Cheng, J. Zhang, S.T. Zheng, M.B. Zhang, G.Y. Yang, Angew. Chem. Int. Ed. 45 (2006) 73. X.J. Gu, D.F. Xue, Cryst. Growth Des. 6 (2006) 2551. X.J. Gu, D.F. Xue, Inorg. Chem. 45 (2006) 9257. X.J. Gu, D.F. Xue, Cryst. Growth Des. 7 (2007) 1726. Y.C. Qiu, H.G. Liu, Y. Ling, H. Deng, R.H. Zeng, G.Y. Zhou, M. Zeller, Inorg. Chem. Commun. 10 (2007) 1399. H. Deng, Z.H. Liu, Y.C. Qiu, Y.H. Li, M. Zeller, Inorg. Chem. Commun. 11 (2008) 978. J.X. Zou, R.H. Zeng, W.G. Zhang, H. Deng, M. Zeller, Inorg. Chem. Commun. 11 (2008) 1347. R. Gheorghe, M. Andruh, A. Müller, M. Schmidtmann, Inorg. Chem. 41 (2002) 5314. M. Eddaoudi, D.B. Moler, H. Li, B. Chen, T.M. Reineke, M. O’Keeffe, O.M. Yaghi, Acc. Chem. Res. 38 (2005) 319. G.M. Sheldrick, A Program for the Siemens Area Detector ABSorption Correction, University of Gottingen, 1997. (a) G.M. Sheldrick, SHELXS97 Program for Solution of Crystal Structures, University of Göttingen, Göttingen, Germany, 1997; (b) G.M. Sheldrick, SHELXL97 Program for Solution of Crystal Structures, University of Göttingen, Germany, 1997. L.J. Bellamy, The Infrared Spectra of Complex Molecular, Wiley, New York, 1958. W.J. Evans, M.S. Sollberger, J. Am. Chem. Soc. 108 (1986) 6005. O. Poncelet, J.S. William, L.G. Hubert-Pfalzgraf, K. Fotling, K.G. Cautton, Inorg. Chem. 28 (1989) 263. R.G. Xiong, J.L. Zuo, Z. Yu, X.Z. You, W. Chen, Inorg. Chem. Commun. 2 (1999) 490. W.J. Evans, M.A. Greci, J.W. Ziller, Inorg. Chem. 39 (2000) 3213. M. Kritikos, M. Moustiakimov, M. Wijk, G. Westin, J. Chem. Soc. Dalton Trans. (2001) 1931. G. Westin, M. Moustiakimov, M. Kritikos, Inorg. Chem. 41 (2002) 3249.
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Synthesis and structural characterization of a novel two-dimensional 3d-4f heterometallic coordination framework based on pentanuclear lanthanide cluster Guo-Ming Wang a, *, Jin-Hua Li a, Zeng-Xin Li a, Pei Wang a, Ying-Xia Wang b, Jian-Hua Lin b a b
Teachers College, College of Chemistry, Chemical Engineering and Environment of Qingdao University, Shandong 266071, China Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China
a r t i c l e i n f o
a b s t r a c t
Article history: Received 22 July 2011 Received in revised form 13 December 2011 Accepted 23 January 2012 Available online 30 January 2012
A novel 3d-4f heterometallic coordination polymer, {[Tm5(m3-OH)2(BDC)6(IN)2Cu(H2O)2]$(H2O)3}n (1) [BDC ¼ benzene-1,2-dicarboxylate, IN ¼ isonicotinate], has been hydrothermally synthesized and structurally characterized by single crystal X-ray diffraction, FTIR, elemental analysis, powder X-ray diffraction and thermogravimetric analysis. The compound crystallizes in monoclinic system, space group P21/c (No. 14), a ¼ 13.7302(5) Å, b ¼ 23.5428(3) Å, c ¼ 21.5789(2) Å, b ¼ 91.491(3) , V ¼ 6973.0(3) Å3, and Z ¼ 4. The structure exhibits unusual two-dimensional Tm-carboxylate layer, which is constructed from the expansion of novel pentanuclear {Tm5} clusters. More interestingly, the heterometallic Cu(I) ions were successfully planted into such Ln-carboxylate layer by the bifunctional IN bridging ligands, resulting in the formation of an unprecedented 2D heterometallic lanthanide-transition-metal framework. Ó 2012 Elsevier Masson SAS. All rights reserved.
Keywords: Hydrothermal synthesis Coordination polymer Crystal structure Isonicotinic acid 1,2-benzenedicarboxylic acid TmeCu heterometallic complex
1. Introduction Design and construction of metal-organic frameworks (MOFs) have attracted extensive interest over the last decades due to their intriguing variety of architectures and structural topologies, as well as their potential applications in catalysis, gas storage and separation, guest exchange, magnetism and luminescence, etc [1e9]. Intelligent ligand design or selection and appropriate choice of the metal centers with suitable coordination geometries are usually the main keys to the construction of such coordination polymers. In this context, a large number of homometallic MOFs possessing either d-block transition-metal (TM) or f-block lanthanide (Ln) ions have been obtained by conventional solution syntheses or hydrothermal techniques [10e16]. By contrast, the progress of the analogous chemistry of heterometallic Ln-TM compounds still remains less developed [17e26]. This is not only because of the high, variable coordination numbers and versatile coordination geometry characteristics of the Ln ions, but also due to the different competitive reactions between the Ln and TM ions and the organic ligands. Fortunately, the Ln and TM ions have different affinities for O- and N-donors, which thus provide high likelihood for construction of unusual heterometallic Ln-TM architectures by choosing * Corresponding author. Tel./fax: þ86 532 85956024. E-mail address: [email protected] (G.-M. Wang). 1293-2558/$ e see front matter Ó 2012 Elsevier Masson SAS. All rights reserved. doi:10.1016/j.solidstatesciences.2012.01.018
multifunctional ligands with both O and N donors. Isonicotinic acid (HIN), for example, is such a potential bifunctional ligand and widely used to construct new hetero-Ln-TM frameworks, in which the carboxylate group is likely to coordinate to hard lanthanide ions and the relatively softer nitrogen atom favors to bind to soft transitionmetal ions such as Ag(I) or Cu(I) [27e35]. This prompted us to choose it as an effective bridging ligand in constructing new hetero-Ln-TM compounds. On the other hand, high-nuclear lanthanide cluster entities as secondary building units (SBUs) have been proved as an effective and powerful synthetic strategy in constructing new MOFs [36]. Therefore, another complementary organic ligand with dicarboxylate groups, i.e. 1,2-benzenedicarboxylic acid (H2BDC), is intentionally introduced and believed to be an ideal candidate to incorporate more lanthanide centers into one cluster. Certainly, synthesizing complexes with mixed IN and BDC ligands is also a challenge due to the competitive coordination. Fortunately, as a result of our attempts such a hetero-Ln-TM compound, {[Tm5(m3-OH)2(BDC)6(IN)2Cu(H2O)2]$(H2O)3}n (1) was obtained from spontaneous assembly of mixed metal ions and ligands under hydrothermal conditions. Indeed, our results show that the lanthanide Tm(III) ions can be held together by BDC ligands to form novel pentanuclear {Tm5} cluster, which themselves are further interconnected to form a 2D architecture. The hetero-copper(I) centers, as expected, are successfully introduced by the bifunctional IN ligands to form an unprecedented hetero-Ln-TM MOFs.
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G.-M. Wang et al. / Solid State Sciences 14 (2012) 445e450 Table 2 Selected bond length (Å) for 1.a
Fig. 1. Experimental and simulated X-ray powder diffraction pattern of complex 1.
2.1. Synthesis The title compound was synthesized under mild hydrothermal conditions. Typically, a mixture of Tm2O3 (0.191 g, 0.5 mmol), HIN (0.193 g,1.6 mmol), H2BDC (0.170 g,1.0 mmol), Cu(NO3)2$3H2O(0.055 g, 0.25 mmol) and H2O (10 ml) was stirred at room temperature. The mixture was sealed in a Teflon-lined autoclave and heated at 170 C for 6 days and then cooled to room temperature. Yellow prism-like crystals was recovered by filtration, washed with distilled water, and dried in air (62% yield based on Tm). Attempts to make other isomorphous compouns with other Ln ions like Tb, Dy, Er and Yb, under the same condition were fruitless. Anal. Found: C, 31.78; H, 2.04; N, 1.18%. Calcd: C, 31.86; H, 1.96; N, 1.24%. IR (KBr pellet, cm1): 3446 m, 1632 s, 1586 s, 1543 s, 1496 w, 1412 s, 1249 w, 1158 w, 1140 w, 1090 w, 1061 w, 876 w, 828 w, 773 m, 684 m, 649 w, 443 w. Table 1 Crystal data and structure refinement for 1.
Reflection collected/unique Completeness to q ¼ 26.49 Absorption correction Refinement method Goodness-of-fit on F2 Final R1, wR2[I > 2s(I)] R indices (all data) Largest diff. peak and hole (e Å3)
2.525(6) 2.425(6) 2.420(7) 2.340(7) 2.438(6) 2.531(6) 2.254(6) 2.357(6) 2.264(6) 2.265(6) 2.307(6) 2.281(7) 2.429(7) 2.368(6) 2.380(6) 2.338(7) 2.280(6) 2.236(6) 2.224(7) 2.306(6) 2.281(7) 2.262(6) 2.295(6) 2.422(5)
Tm(3)eO(26) Tm(4)eO(8) Tm(4)eO(19) Tm(4)eO(20) Tm(4)eO(21) Tm(4)eO(24) Tm(4)eO(26) Tm(4)eO(27) Tm(4)eO(32) Tm(5)eO(1)#2 Tm(5)eO(11) Tm(5)eO(12) Tm(5)eO(15) Tm(5)eO(16) Tm(5)eO(23) Tm(5)eO(24) Tm(5)eO(26) Tm(5)eO(31) Cu(1)eN(1) Cu(1)eN(2)#3 Tm(2)eTm(3) Tm(3)eTm(4) Tm(4)eTm(5)
2.449(5) 2.279(7) 2.423(6) 2.410(6) 2.265(6) 2.286(6) 2.368(6) 2.340(7) 2.271(6) 2.263(6) 2.397(6) 2.384(6) 2.475(6) 2.451(6) 2.552(6) 2.411(6) 2.362(6) 2.281(7) 1.886(8) 1.893(8) 3.8836(6) 3.8762(6) 3.8091(7)
a Symmetry transformations used to generate equivalent atoms: #1 -xþ2, yþ1/2, -zþ3/2; #2 -xþ1, y-1/2, -zþ3/2; #3 x, y-1, z.
2. Experimental
Empirical formula Formula weight Temperature (K) Wavelength (Å) Crystal system Space group A (Å) b (Å) c (Å) b ( ) V (Å3) Z, Calculated density (g cm3) Absorption coefficient (mm1) F(000) Crystal size (mm) q range for data collection/ Limiting indices
Tm(1)eO(3) Tm(1)eO(4) Tm(1)eO(5) Tm(1)eO(6) Tm(1)eO(17) Tm(1)eO(18) Tm(1)eO(22)#1 Tm(1)eO(25) Tm(1)eO(29) Tm(2)eO(2) Tm(2)eO(4) Tm(2)eO(9) Tm(2)eO(13) Tm(2)eO(14) Tm(2)eO(25) Tm(2)eO(28) Tm(2)eO(30) Tm(3)eO(7) Tm(3)eO(10) Tm(3)eO(14) Tm(3)eO(15) Tm(3)eO(18) Tm(3)eO(20) Tm(3)eO(25)
The X-ray powder diffraction pattern for the bulk product is in good agreement with the pattern based on single-crystal X-ray solution in position, indicating the phase purity of the as-synthesized samples of the title compound (Fig. 1). 2.2. Characterization Infrared spectra were obtained from sample powder pelletized with KBr on an ABB Bomen MB 102 series FTIR spectrophotometer over a range 400e4000 cm1. Powder X-ray diffraction (XRD) data were obtained using a Philips X’Pert-MPD diffractometer with Cu-Ka1 radiation (l ¼ 1.54076 Å). The elemental analysis was carried out on an Elemental Vario EL III CHNOS elemental analyzer. The thermogravimetric analysis (TGA) was performed on a Mettler Toledo TGA/SDTA 851e analyzer in N2 atmosphere with a heating rate of 10 C/min. 2.3. Determination of crystal structure
C60H44CuN2O35Tm5 2261.16 295(2) 0.71073 Monoclinic P21/c 13.7302(5) 23.5428(3) 21.5789(2) 91.491(3) 6973.0(3) 4, 2.154 6.689 4288 0.10 0.10 0.05 1.48e26.00 16 h 16,28 k 29, 26 l 26 54132/13692 [R(int) ¼ 0.1044] 99.9% Semi-empirical from equivalents Full-matrix least-squares on F2 1.084 R1 ¼ 0.0464, wR2 ¼ 0.0736 R1 ¼ 0.0867, wR2 ¼ 0.0776 1.234 and 1.009
A suitable single crystal of as-synthesized compound with the dimensions of 0.10 0.10 0.05 mm3 was carefully selected under
Fig. 2. IR spectrum of 1.
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Fig. 3. ORTEP view of the coordination environment of Tm and Cu ions in complex 1 with thermal ellipoids at the 50% probability level. All H atoms are omitted for clarity. Symmetry code: (i) 1-x, 0.5 þ y, 1.5-z; (ii) 2-x, 0.5 þ y, 1.5-z; (iii) x, 1 þ y, z.
an optical microscope and glued to thin glass fiber with epoxy resin. Crystal structure determination by X-ray diffraction was performed on a Siemens SMART CCD diffractometer with graphitemonochromated Mo Ka (l ¼ 0.71073 Å) in the u and f scanning mode at room temperature. An empirical absorption correction was applied using the SADABS program [37]. The structure was solved by direct methods using SHELXS-97 [38]. The heavy atoms were first located, and other non-H atoms were found in the successive Fourier difference maps. The H atoms of organic ligands were geometrically placed and refined using a riding model. However, the H atoms of water molecules have not been included in the final refinement. The structures were refined on F2 by full-matrix leastsquares methods using the SHELXL-97 program package [38]. All non-hydrogen atoms were refined anisotropically. Crystallographic data and selected bond distances for 1 are listed in Tables 1 and 2, respectively. 3. Results and discussion 3.1. Infrared (IR) spectrum The FTIR spectrum of the title compound is shown in Fig. 2. The strong and broad absorption bands at around 3446 cm1 is
assigned to the vibrations of coordinating or noncoordinating water molecules. The strong bands appearing around 1586 and 1412 cm1 are characteristic of the asymmetric and symmetric stretching vibrations of the carboxylate group, respectively. No strong bands ranging from 1690 to 1730 cm1 indicate that all carboxyl groups of organic ligands are deproponated [39]. 3.2. Crystal structure The asymmetric unit of 1 consists of five crystallographically unique Tm(III) ions, one Cu(I) ion, two m3-OH ions, two IN and six BDC2 ions, two coordinated and three noncoordination water molecules. As shown in Fig. 3, atoms Tm(1) and Tm(5) are both nine-coordinate with tricapped trigonal prism configurations and the same coordination environments: one m3-OH, six carboxylate oxygen atoms (OCOO) from three BDC ligands and two coordinated water molecules. Tm(2), Tm(3) and Tm(4) centers, however, are eight-coordinated and have bicapped trigonal prism coordination geometries: one m3-OH, five OCOO from three BDC ligands, one OCOO from one IN ligand and one coordinated water molecule for Tm(2) and Tm(3), respectively; two m3-OH and six OCOO from four BDC ligands for Tm(4). The TmeO bond lengths range from 2.229(6) to 2.531(6) Å. The OeTmeO bond angles are in the range of 51.6
Fig. 4. View of the structure of {Tm5} cluster.
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Fig. 5. View of the structure of 2D lanthanide layer constructed by {Tm5} clusters.
(8)-154.1 (2) . The six BDC ligands are completely deprotonated and exhibit three types of coordination modes (Chart 1aec), simultaneously coordinating three Tm(III) ions in tetra-, pentaand hexadentate chelating-bridging modes, respectively. Both IN ligands, however, adopt the same tridentate bridging mode: the nitrogen atom coordinates to the Cu center and the carboxylate connects to two Tm centers in a bimonodentate fashion (1 d). The Cu atom has a nearly linear configuration defined by two N atoms from two bridging IN ligands. Interestingly, although copper(II) salts were used as starting materials, the Cu center in the product is in the þ1 oxidation state, which may be attributed to a reduction reaction occurring under the hydrothermal conditions used. The CueN distances are typical, varying from 1.885(8) to 1.893(8) Å, and the NeCueN bond angle is 165.6(4) . Five Tm(III) centers, occurring in the same plane, are held together by two m3-OH groups, two IN and six BDC ligands to built up
Chart 1. Coordination modes of BDC and IN ligands in Complex 1.
a novel pentanuclear cluster, [Tm5(m3-OH)2(bdc)6(IN)2(H2O)2] (Fig. 4). In the core, the {Tm5} skeleton can be conceptually regarded as consisting of two identical equilateral triangles, Tm(1)Tm(2) Tm(3) and Tm(3)Tm(4)Tm(5). Each side of the two equilateral triangles has a mean Tm-Tm separation of w3.884 Å, and the angles formed by the three Tm centers are roughly 58.1, 60.1 and 61.8 , respectively. Two m3-OH groups, O(25)H and O(26)H, orientate in the same direction and capped on each triangular face. The distance of the m3-OH unit to the triangular metal face is ca. 1.0 Å. It worthy to note that odd pentanuclear lanthanide cluster is particularly rare [40e45], though a few tetra-, penta-, hexa- hepta-, octa-, nona-, dodeca-, tetradeca- and pentadecanuclear lanthanide clusters have been reported. More importantly, the present {Tm5} cluster in 1 is distinct from the square pyramidal geometry found in other Ln5 clusters, and is firstly observed either in a discrete molecule or as a fragment in a higher nuclearity lanthanide complex. Each {Tm5} cluster is connected in turn to four neighboring {Tm5} groups by four BDC anions in coordination modes 1b to give an interesting 2D lanthanide layer with rhombic cavities along the direction of the c-axis (Fig. 5). Those BDC ligands in modes 1a and 1c, however, are solely responsible for the assembly of the pentanuclear lanthanide cluster, and make no contribution to the expansion of such {Tm5} clusters into 2D network. The rhombus size is ca. 17.44 11.56 Å (defined by the separation between two opposite Tm centers). However, these huge cavities are not empty and occupied by [Cu(IN)2] moieties, which seem like many longspan bridges flying across the cavities. As shown in Fig. 6, besides providing the carboxylate groups (eCOO) to coordinate to the {Tm5} core, the IN ligands are simultaneously responsible to introduce the softer Cu(I) ions into the lanthanide layer through eNeCu(I)eNe coordination bonds. Thus, an unprecedented 2D heterometallic Ln-TM network involving mixed BDC and IN ligands is obtained. It must to be pointed out that, although several 3D 3d4f and 4d-4f heterometallic Ln-TM coordination polymers
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Fig. 6. View of the 2D structure of heterometallic Tm-Cu network.
incorporating IN ligand have been reported recently [21,27e34], the design and construction of 2D 3d-4f heterometallic coordination frameworks still remains undeveloped. Interestingly, if we treated the {Tm5Cu} cluster as the SBUs, complex 1 exhibits a sixconnected network (Fig. 7). A topological analysis of this net was performed with OLEX which gives the short vertex (Schäfli) symbol 364653. Meanwhile, the adjacent 2D layers are packed in an ABAB sequence along the c-axis (Fig. 8). All benzene rings of the BDC ligands are alternately distributed up and down each layer, acting as an organic skin to wrap the neighboring layers into a perfect inorganic-organic sandwich structure.
Fig. 7. The 2D topological network of 1 viewed along the c direction. Yellow balls are the six-connected nodes and represent the {CuTm5} units. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
Fig. 8. The packing of the 2D heterometallic Tm-Cu layers along [001] direction with the ABAB sequence.
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Appendix. Supplementary material Supplementary material associated with this article can be found, in the online version, at doi:10.1016/j.solidstatesciences. 2012.01.018. References [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] Fig. 9. TG curve of 1. [12] [13]
3.3. Thermal property The thermogravimetric analysis (TGA) was performed in dry N2 atmosphere from 30 to 800 C with a heating rate of 10 C/min. As shown in Fig. 9, the lattice-water and the coordinated water molecules were gradually lost in the temperature range 30e280 C (observed: 4.22%; expected: 3.98%). On further heating, a continuous weight loss of 30.02% occurred in the range from 280 to 970 C, corresponding to the decomposition and removal of the organic ligands (observed: 54.58%; expected: 54.95%).
[14] [15] [16] [17] [18] [19] [20] [21] [22] [23]
4. Conclusions In summary, a novel 3d-4f heterometallic coordination polymer with the formula {[Tm5(m3-OH)2(BDC)6(IN)2Cu(H2O)2]$(H2O)3}n (1), had been synthesized and structurally characterized. Its structure contains unprecedented homometallic {Tm5} clusters, which themselves can propagate to give 2D Ln-carboxylate layer with mixed BDC and IN ligands. The heterometallic Cu(I) ions, as expected, were successfully planted into the 2D Ln-carboxylate layer by the bifunctional IN ligands with preferential coordination sites. Besides providing an intriguing example of heterometallic coordination polymer, this work also indicates that it is promising to construct new unusual architectures by using lanthanide-based SBUs. Further studies on this perspective are now under way in our laboratory.
[24] [25] [26] [27] [28] [29] [30] [31] [32] [33] [34] [35] [36] [37] [38]
Acknowledgement We gratefully acknowledge the financial support from the National National Natural Science Foundation of China (No. 20901043), Beijing National Laboratory for Molecular Sciences (BNLMS), the Young Scientist Foundation of Shandong Province (No. BS2009CL041) and the Natural Science Foundation of Shandong Province (No. ZR2009FQ022).
[39] [40] [41] [42] [43] [44] [45]
S. Kitagawa, R. Matsuda, Coord. Chem. Rev. 251 (1997) 2490. S.R. Batten, R. Robson, Angew. Chem. Int. Ed. 37 (1998) 1460. S. Noro, S. Kitagawa, M. Kondo, K. Seki, Angew. Chem. Int. Ed. 39 (2000) 2082. M. Shibasaki, N. Yoshikawa, Chem. Rev. 102 (2002) 2187. J. Kido, Y. Okamoto, Chem. Rev. 102 (2002) 2357. O.M. Yaghi, M. O’Keeffe, N.W. Ockwig, H.K. Chae, M. Eddaoudi, J. Kim, Nature 423 (2003) 705. D. Bradshaw, J.B. Claridge, E.J. Cussen, T.J. Prior, M.J. Rosseinsky, Acc. Chem. Res. 38 (2005) 273. X. Guo, G. Zhu, Z. Li, F. Sun, Z. Yang, S. Qiu, Chem. Commun. 9 (2006) 3172. R. Banerjee, A. Phan, B. Wang, C. Knobler, H. Furukawa, M. O’Keeffe, O.M. Yaghi, Science 319 (2008) 939. G.B. Gardner, D. Venkataraman, J.S. Moore, S. Lee, Nature 374 (1995) 792. O.R. Evans, R. Xiong, Z. Wang, G.K. Wong, W. Lin, Angew. Chem. Int. Ed. 38 (1999) 536. M.H. Zeng, W.X. Zhang, X.Z. Sun, X.M. Chen, Angew. Chem. Int. Ed. 44 (2005) 3079. Q.R. Fang, G.S. Zhu, Z. Jin, M. Xue, X. Wei, D.J. Wang, S.L. Qiu, Angew. Chem. Int. Ed. 45 (2006) 616. M.R. BNrgstein, M.T. Gamer, P.W. Roesky, J. Am. Chem. Soc. 126 (2004) 5213. Y. Wan, L. Zhang, L. Jin, S. Gao, S. Lu, Inorg. Chem. 42 (2003) 4985. Y.Q. Sun, J. Zhang, Y.M. Chen, G.Y. Yang, Angew. Chem. Int. Ed. 44 (2005) 5814. B. Zhao, P. Cheng, X.Y. Chen, C. Cheng, W. Shi, D.Z. Liao, S.P. Yan, Z.H. Jiang, J. Am. Chem. Soc. 126 (2004) 3012. B. Zhao, X.Y. Chen, P. Cheng, D.Z. Liao, S.P. Yan, Z.H. Jiang, J. Am. Chem. Soc. 126 (2004) 15394. B. Zhao, H.L. Gao, X.Y. Chen, P. Cheng, W. Shi, D.Z. Liao, S.P. Yan, Z.H. Jiang, Chem. Eur. J. 12 (2006) 149. X.Q. Zhao, B. Zhao, Y. Ma, W. Shi, P. Cheng, Z.H. Jiang, D.Z. Liao, S.P. Yan, Inorg. Chem. 46 (2007) 5832. J.W. Cheng, S.T. Zheng, G.Y. Yang, Inorg. Chem. 46 (2007) 10534. Y.C. Qiu, H.G. Liu, Y. Ling, H. Deng, R.H. Zeng, G.Y. Zhou, M. Zeller, Inorg. Chem. Commun. 10 (2007) 1399. Z.H. Liu, Y.C. Qiu, Y.H. Li, G. Peng, B. Liu, H. Deng, Inorg. Chem. Commun. 12 (2009) 204. M. Sakamoto, K. Manseki, H. Okawa, Coord. Chem. Rev. 219-221 (2001) 379. C. Benelli, D. Gatteschi, Chem. Rev. 102 (2002) 2369. M. Andruh, J.P. Costes, C. Diaz, S. Gao, Inorg. Chem. 48 (2009) 3342. M.B. Zhang, J. Zhang, S.T. Zheng, G.Y. Yang, Angew. Chem. Int. Ed. 44 (2005) 1385. J.W. Cheng, J. Zhang, S.T. Zheng, M.B. Zhang, G.Y. Yang, Angew. Chem. Int. Ed. 45 (2006) 73. X.J. Gu, D.F. Xue, Cryst. Growth Des. 6 (2006) 2551. X.J. Gu, D.F. Xue, Inorg. Chem. 45 (2006) 9257. X.J. Gu, D.F. Xue, Cryst. Growth Des. 7 (2007) 1726. Y.C. Qiu, H.G. Liu, Y. Ling, H. Deng, R.H. Zeng, G.Y. Zhou, M. Zeller, Inorg. Chem. Commun. 10 (2007) 1399. H. Deng, Z.H. Liu, Y.C. Qiu, Y.H. Li, M. Zeller, Inorg. Chem. Commun. 11 (2008) 978. J.X. Zou, R.H. Zeng, W.G. Zhang, H. Deng, M. Zeller, Inorg. Chem. Commun. 11 (2008) 1347. R. Gheorghe, M. Andruh, A. Müller, M. Schmidtmann, Inorg. Chem. 41 (2002) 5314. M. Eddaoudi, D.B. Moler, H. Li, B. Chen, T.M. Reineke, M. O’Keeffe, O.M. Yaghi, Acc. Chem. Res. 38 (2005) 319. G.M. Sheldrick, A Program for the Siemens Area Detector ABSorption Correction, University of Gottingen, 1997. (a) G.M. Sheldrick, SHELXS97 Program for Solution of Crystal Structures, University of Göttingen, Göttingen, Germany, 1997; (b) G.M. Sheldrick, SHELXL97 Program for Solution of Crystal Structures, University of Göttingen, Germany, 1997. L.J. Bellamy, The Infrared Spectra of Complex Molecular, Wiley, New York, 1958. W.J. Evans, M.S. Sollberger, J. Am. Chem. Soc. 108 (1986) 6005. O. Poncelet, J.S. William, L.G. Hubert-Pfalzgraf, K. Fotling, K.G. Cautton, Inorg. Chem. 28 (1989) 263. R.G. Xiong, J.L. Zuo, Z. Yu, X.Z. You, W. Chen, Inorg. Chem. Commun. 2 (1999) 490. W.J. Evans, M.A. Greci, J.W. Ziller, Inorg. Chem. 39 (2000) 3213. M. Kritikos, M. Moustiakimov, M. Wijk, G. Westin, J. Chem. Soc. Dalton Trans. (2001) 1931. G. Westin, M. Moustiakimov, M. Kritikos, Inorg. Chem. 41 (2002) 3249.