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One-dimensional salen-type heterospin trimetallic (3d–4f–3d′) chain-like coordination polymers: Syntheses, crystal structures and magnetic properties
Inorganic Chemistry Communications 13 (2010) 171–174
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Inorganic Chemistry Communications journal homepage: www.elsevier.com/locate/inoche
One-dimensional salen-type heterospin trimetallic (3d–4f–3d0 ) chain-like coordination polymers: Syntheses, crystal structures and magnetic properties Wen-Bin Sun a, Peng-Fei Yan a,*, Guang-Ming Li a, Ju-Wen Zhang a, Ting Gao a, Masayuki Suda b, Yasuaki Einaga b,* a
Key Laboratory of Functional Inorganic Material Chemistry (HLJU), Ministry of Education, School of Chemistry and Materials Science, Heilongjiang University, No. 74, Xuefu Road, Nangang District, Harbin 150080, PR China Keio University, 3-14-1 Hiyoshi, Yokohama 223-8522, Japan
b
a r t i c l e
i n f o
Article history: Received 17 July 2009 Accepted 13 November 2009 Available online 17 November 2009 Keywords: Salen-type ligand Heterospin Trimetallic polymer Structure Magnetic properties
a b s t r a c t Three one-dimensional (1D) heterospin trimetallic chain-like polymers [{LCu(H2O)}Ln(MeOH)(H2O)2{(lCN)2Fe(CN)4}]2H2O (1, Ln = La; 2, Ln = Nd; 3, Ln = Gd) were prepared by substitution of the nitrato ligands in [LCuLn] complexes with [Fe(CN)6]3 ions (H2L = N,N0 -bis(3-methoxysalicylidene)propane-1,2diamine). Single-crystal X-ray diffraction analysis revealed that the methyl on the salen-type ligand impeded the connection between cyanide groups and Cu(II) ions efficiently. Consequently, three novel one-dimensional (1D) trimetallic chain-like polymers were obtained with the linker [Fe(CN)6]3 ions interacting only with the lanthanide ions. The magnetic investigation for 3 indicated a ferrimagnetic chain may form. Ó 2009 Elsevier B.V. All rights reserved.
The design and construction of supramolecular solid-state architectures with heterospin carriers are of high interest in the field of molecular magnetism [1]. However, the number of heterospin coordination polymers is limited to a few examples [1a,2]. The first trimetallic 3d–3d0 –3d00 complexes were reported by Chaudhuri and co-workers [3]. Recently, Costes and Andruh and co-workers are developing a synthetic approach aiming at obtaining heterospin multinuclear complexes. It is based on the employment of bimetallic d–f complexes as starting materials, with the nitrato groups being replaced by the hexacyanometallates [M(CN)6]3 (M = Cr(III), Fe(III), Co(III)) carrying the third spin carrier. Under this strategy, the first 2p–3d–4f heterospin system, 3d–3d0 –4f trimetallic and 3p–3d–4f complexes have been obtained [4,2c,5]. Since the cyanide nitrogen atoms of the hexacyanometallates are strong donor groups that could link both transition metal and lanthanide ions, most of the heterospin coordination polymers constructed by the hexacyanometallates are multidimensional [1]. From a magnetic point of view, the understanding of the magnetic properties correlating to structure is still far from being satisfactory [1a]. Thus, using of blocking organic ligands to reduce the dimensionality of heterospin coordination polymers is deserved to be further investigated for the purpose of clearly elucidating
* Corresponding authors. Tel.: +86 451 86608399; fax: +86 451 86608042 (P.-F. Yan). E-mail addresses: [email protected] (P.-F. Yan), [email protected] (Y. Einaga). 1387-7003/$ - see front matter Ó 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.inoche.2009.11.006
magneto-structural correlations and preparing interesting molecular materials such as single-molecule magnets (SMMs) and singlechain magnets (SCMs) [1b,1c]. We are exploring a strategy to control the solid structure of salen-type 4f and 3d–4f complexes and study their physicochemical properties [6]. In order to obtain the low-dimensional heterospin coordination polymer, a salen-type ligand with a methyl on the lateral alkane diamino chain was used. The steric influence of methyl impeded the linking between cyanide groups and Cu(II) ions successfully, and consequently three 1D trimetallic chain-like polymers were obtained. We herein present the syntheses, crystal structures and magnetic properties of the complexes. The starting heterodinuclear [LCuGd] (H2L = N,N0 -bis(3-methoxysalicylidene)propane-1,2-diamine) complexes were prepared according to literatures [6b,7,8]. The trimetallic coordination polymers 1–3 were easily prepared [2c,9] by diffusion of a methanol solution of [LCuGd] complexes to an aqueous solution of K3[Fe(CN)6]. The resulting dark-green micro-crystalline precipitate was filtered and characterized by single-crystal X-ray diffraction [10], elemental analysis, FT-Infrared (IR) spectrum (Fig. S1) and thermogravimetric analysis (TGA). The IR spectra of complexes 1–3 exhibit broad absorptions centered at 3410 cm1 associated with the O–H stretching vibrations of H2O molecules in this structure. The band centered at 1634 cm1 is attributed to the characteristic stretching vibration of the imine (C@N) group. The single peak that appears at around 2119 cm1 is assigned to the m(C„N) stretching mode of the cyanide group in accordance with
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the literatures [11]. Single-crystal X-ray diffraction analysis reveals that complexes 1–3 are isomorphic. Take complex 3 as an example to describe their structures, which crystallizes in the triclinic P1 space group. A perspective view of the complex 3 with the atomlabeling scheme and selected bond lengths and angles is given in Fig. 1. The [LCuGd] moiety preserves the structural features of the whole [Cu(II)Ln(III)] family of complexes with compartmental salen-type ligands [7,8]. The Cu(II) ion is hosted in the inner N2O2 compartment, and the oxophilic Gd(III) ion occupies the outer O4 cavity. The two metal ions are doubly bridged through sharing the two phenolic oxygen atoms from the ligand. The Cu–Gd distance is 3.4301 Å which is shorter than 3.5083 Å of the first salen-type 3d–3d0 –4f complex [Cu(salpn)Gd(H2O)3 {Fe(CN)6}]4H2O(salpn2 = N,N0 -propylenedi(3-methoxysalicylidenei-minato) [2c].
Fig. 1. Perspective view of the coordination environment of the Cu(II), Gd(III) and Fe(III) centers in 3 with atoms represented by 30% thermal ellipsoids. Selected bond lengths (Å) and angles (°): Cu(1)–N(1) 1.908(4), Cu(1)–N(2) 1.918(4), Cu(1)–O(1) 1.925(3), Cu(1)–O(3) 1.904(3), Cu(1)–O(5) 1.941(4), Gd(1)–O(1) 2.372(3), Gd(1)– O(3) 2.377(3), Gd(1)–O(2) 2.701(3), Gd(1)–O(4) 2.628(3), Gd(1)–N(5) 2.469(4), Gd(1)–N(6), 2.553(3), Gd(1)–O(6) 2.423(3), Gd(1)–O(7) 2.444(3), Gd(1)–O(8) 2.424(3), Fe(1)–C(20) 1.941(4), Fe(1)–C(21) 1.943(5), Fe(1)–C(22) 1.946(5), Fe(2)– C(23) 1.941(4), Fe(2)–C(24) 1.943(5), Fe(2)–C(25) 1.944(4), N(5)–C(20) 1.149(5), N(6)–C(23) 1.147(5), Gd(1)–N(5)–C(20) 171.80(3), Gd(1)–N(6)–C(23) 146.90(3), Fe(2)–C(23)–N(6) 172.78(3), Fe(1)–C(20)–N(5) 178.04(4), O(1)–Gd(1)–O(2) 61.34(9), O(3)–Gd(1)–O(4) 60.83(9), Cu(1)–O(1)–Gd(1) 105.47(11), Cu(1)–O(3)– Gd(1) 105.95(11). Selected bond lengths and angles of 1 and 2 listed in Table S1.
Since the steric effect of methyl on the lateral alkane diamino chain of the ligand, the cyanide groups interacts only with the Gd(III) ions not Cu(II) ions. A schematic view of the chain of [LCuGdFe]n is shown in Fig. 2. Each [Fe(CN)6]3 unit attaches two Gd(III) ions using two trans cyanide groups, while each [LCuGd] group connects two [Fe(CN)6]3 moieties in a cis fashion. The chains show an alternation of [{LCu(H2O)}Gd(MeOH)(H2O)2] and [Fe(CN)6]3 fragments linked by cyanide bridges in the transgeometry. The angels Fe(1)–C(20)„N(5) and Fe(2)–C(23)„N(6) are 178.04° and 172.78°, which indicates a bent cyanide bridge due to the steric hindrance of the [LCuGd] entity. The angles Gd– Fe–Gd and Fe–Gd–Fe are different (180.00° and 122.61°) along the chain. The chains are not in a linear configuration and trinuclear entities [GdFeGd] run along the chain in a zigzag path. As each Gd(III) ion is related to the neighboring one by a glide plane, there are two enantiomeric coordination spheres in a chain, which is similar to some [CuGd] coordination polymers [12]. To our knowledge, one of the closed related complexes to 1–3 is the heterotrinuclear complex [Cu(salpn)Gd(H2O)3{Fe(CN)6}]4H2O [2c]. However, the crystallographic analysis revealed that their structures are very different. Firstly, the polymeric structure of [Cu(salpn)Gd(H2O)3{Fe(CN)6}]4H2O has a ladder topology built up of [Gd2Fe2Cu] pentagous that share the [FeGd] edges. Each [Fe(CN)6]3 group connects three heterodinuclear [CuGd] units with the cyanide groups linking both the Cu(II) and lanthanide(III) ions. Complex 1–3 prefer to be, however, a unique 1D chain-like structure through trans cyanide bridges between lanthanide(III) and iron(III) ions. Secondly, the Gd(III) ions in [Cu(salpn)Gd(H2O)3{Fe(CN)6}]4H2O are eight-coordinated while lanthanide(III) ions in 1–3 are nine-coordinated. Obviously, the above mentioned differences are attributed to the size of lanthanide ions and the selected ligand. In complex 3, the distances between metal ions of adjacent chains are separate distinctly with the shortest distance 7.1198 Å (Cu–Fe), 9.1785 Å (Cu–Cu) and 9.7849 Å (Cu–Gd), respectively (Fig. 2). Furthermore, there are coordinated and interstitial waters between the chains in complexes 1–3 and each aqua molecule is hydrogen-bonded to uncoordinated cyanide nitrogen atom of an adjacent chain [O–H–N] and gives an extensive 3D network (Fig. S2). Thermogravimetric analysis (TGA) result indicates that the aqua molecules can be removed before 200 °C with the weight loss of 13.5%, which is consistent with the calculated value 13.6% (Table S2 and Fig. S3). Next, magnetic susceptibility data for 3 were collected in the temperature range 2–300 K at an applied field of 1000 Oe. The
Fig. 2. Perspective view of chains in 3, along with the distances between metal ions of adjacent chain.
W.-B. Sun et al. / Inorganic Chemistry Communications 13 (2010) 171–174
temperature-dependent magnetic susceptibility of 3 in the forms of vmT versus T and v1 m versus T plots are shown in Fig. 3. The value of the vmT product is 8.68 emu mol1 K at room temperature, which is slightly higher than the calculated value (8.62 emu mol1 K) corresponding to the sum of the contributions of the three uncoupled ions, (vmT)HT = (Ng2b2/3k)[SGd(SGd + 1) + SCu (SCu + 1) + SFe(SFe + 1)], gCu = gGd = gFe = 2 [2c]. The similar deviation from calculated value is also found in the first salen-type 3d–4f– 3d0 complex [Cu(salpn)Gd(H2O)3{Fe(CN)6}]4H2O, which contributes to the first-order orbital momentum of the low-spin iron(III) [2c]. The vmT value keeps increase slowly until 90.1 K, where it starts to increase abruptly and reaches a maximum of 9.53 emu mol1 K at 13.9 K. The increase of vmT with a decrease in the temperature suggests the presence of ferromagnetic interactions between paramagnetic centers. The maximum vmT value 9.53 emu mol1 K at 13.9 K is lower than that of complex [Cu(salpn)Gd(H2O)3{Fe(CN)6}]4H2O (9.86 emu mol1 K at 13.8 K) [2c], which should be attributed to the different structure of them. Below 13.9 K, vmT decreases with cooling, first slightly and then abruptly, down to 9.23 emu mol1 K at 2 K. The thermal evolution of v1 m obeyed the Curie-Weiss law, vm = C/(T h), in the temperature range from 13.9 K to room temperature, with the Weiss constant, h, of 0.69 K, the Curie constant, C of 8.65 emu mol1 K. The positive h value suggests a ferromagnetic coupling in 3. This behavior is consistent with that of trimetallic complex [Cu(salpn)Gd(H2O)3{Fe(CN)6}]4H2O [2c]. In light of the literature [2c], a interpretation of the magnetic behavior of 3 is given as follows: above 13.9 K, the Cu(II) and Gd(III) ions are ferromagnetically coupled, resulting in units with S = 4. Below 13.9 K, the vmT product decrease rapidly. This behavior is most likely caused by any the [LCuGd] units further interact antiferromagnetically with the paramagnetic [Fe(CN)6]3 linkers[2c,13], the interchain interaction, the zero-field splitting (ZFS) of the metal centers, or all at the same time [13]. According to the crystal structure of 3 (Fig. 2), the distances between metal ions of adjacent chains are separate obviously and there are no cyanide groups coordinated to Cu(II) ions, which assumes that no magnetic interaction occurs between Cu(II) and Fe(III). Besides, the Gd(III)–NC–Fe(III) chain-like pathway is effective, which is similar to some investigations of [Gd(III)Fe(III)] cyanide-bridged systems [14]. However, the Gd(III)–NC–Fe(III) interaction is supposed to be much weaker than that of Cu(II)– Gd(III) [14]. In combination with the chain-like structural properties, a ferrimagnetic chain [(S = 4)–(S = 1/2)–(S = 4)–(S = 1/2)– ] may form.
Fig. 3. The plots of vmT and v1 m versus T for 3 from 2.0 to 300 K. The solid line represents the best fit to the Curie–Weiss law and the plot of M versus H for 3 at 2 K is inserted.
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To confirm the magnetic behavior of 3, AC magnetic susceptibility and FC-ZFC magnetization measurements were performed. The results are plotted in Figs. S4 and S5. The real v0 and imaginary v00 components of AC magnetic susceptibility do not show any peaks and frequency dependence. The FC-ZFC magnetization curves do not diverge either. These results indicate that there is no magnetic ordering in 3 until 2 K. The field dependence of the magnetization for 3 at 2 K shows the magnetization reaches rapidly saturation at a magnetization value of 8.3 Nb (Fig. 3). The value consist of the saturation value of 8 Nb from the [LCuGd] units (SGd(III) = 7/2, SCu(II) = 1/2, g = 2) and 0.3 Nb of first-order orbital momentum for the low-spin iron(III) [2c]. The M versus H loop curve indicates that no hysteresis is observed (Fig. S6). In summary, three heterospin trimetallic polymers have been prepared and characterized crystallographically and magnetically. Three polymers show a novel chain-like structure formed by the [Fe(CN)6]3 ions bridging between the lanthanide(III) ions. The present work will be helpful in providing valuable information for the design and synthesis of low-dimensional cyanide-bridged heterospin multinuclear polymers. Further magnetic investigation on the new family of polymers is in progress. Acknowledgments This work is financially supported by the National Natural Science Foundation of China (Nos. 20672032 and 50903028), Heilongjiang Province (Nos. QC08C10, GZ08A401, JC200605, 2006FRFLXG031 and 2009RFXXG201), and Key Laboratory of Environment-friendly Chemical Engineering Technology of Heilongjiang Higher Education Institutes, Heilongjiang University. Authors want to thank Prof. Fu-Pei Liang (Guangxi Normal University) for the magnetic measurement. Appendix A. Supplementary material CCDC 625266, 681053, 732858 contain the supplementary crystallographic data for compounds 1, 2, 3, respectively. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif. Supplementary data associated with this article can be found, in the online version, at doi:10.1016/j.inoche.2009.11.006. References [1] (a) M. Andruh, J.P. Costes, C. Diaz, S. Gao, Inorg. Chem. 48 (2009) 3342; (b) D.P. Zhang, H.L. Wang, Y.T. Chen, Z.H. Ni, L.J. Tian, J.Z. Jiang, Inorg. Chem. 48 (2009) 5488; (c) S. Tanase, J. Reedijk, Coord. Chem. Rev. 250 (2006) 2501; (d) D.F. Mullica, J.M. Farmer, J.A. Kautz, Inorg. Chem. Commun. 2 (1999) 73. [2] (a) H.Z. Kou, B.C. Zhou, S. Gao, R.J. Wang, Angew. Chem., Int. Ed. 42 (2003) 3288; (b) H.Z. Kou, B.C. Zhou, R.J. Wang, Inorg. Chem. 42 (2003) 7658; (c) R. Gheorghe, M. Andruh, J.P. Costes, B. Donnadieu, Chem. Commun. (2003) 2778; (d) T. Shiga, H. Okawa, S. Kitagawa, M. Ohba, J. Am. Chem. Soc. 128 (2006) 16426. [3] (a) C.N. Verani, T. Weyhermüller, E. Rentschler, E. Bill, P. Chaudhuri, Chem. Commun. (1998) 2475; (b) C.N. Verani, E. Rentschler, T. Weyhermüller, E. Bill, P.J. Chaudhuri, Chem. Soc. Dalton Trans. (2000) 4263. [4] A.M. Madalan, H.W. Roesky, M. Andruh, M. Noltemeyer, N. Stanica, Chem. Commun. (2002) 1638. [5] A.M. Madalan, N. Avarvari, M. Fourmigué, R. Clérac, L.F. Chibotaru, S. Clima, M. Andruh, Inorg. Chem. 47 (2008) 940. [6] (a) W.B. Sun, P.F. Yan, G.M. Li, H. Xu, J.W. Zhang, J. Solid State Chem. 182 (2009) 381; (b) W.B. Sun, P.F. Yan, G.M. Li, J.W. Zhang, H. Xu, Inorg. Chim. Acta 362 (2009) 1761; (c) T. Gao, P.F. Yan, G.M. Li, G.F. Hou, J.S. Gao, Polyhedron 26 (2007) 5382; (d) P.F. Yan, W.B. Sun, G.M. Li, C.H. Nie, T. Gao, Z.Y. Yue, J. Coord. Chem. 60 (2007) 1973. [7] J.P. Costes, F. Dahan, A. Dupuis, J.P. Laurent, Inorg. Chem. 35 (1996) 2400.
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[8] H. Kara, Y. Elerman, K. Prout, Z. Naturforsch. 55b (2000) 1131. [9] [{LCu(H2O)}Gd(MeOH)(H2O)2{(l-CN)2Fe(CN)4}]2H2O (3) To a MeOH solution (10 mL) of [LCu(Me2CO)Gd(NO3)3] (0.2054 g, 0.25 mmol) was slowly diffused an aqueous solution (6 mL) of K3[Fe(CN)6] (0.0820 g, 0.25 mmol) at room temperature. A dark green crystals formed in one week. Dark green crystals were collected by filtration and washed with water with a 70% yield. Anal. Calcd. for complex 3 C26H34CuFeGdN8O10 (895.25): C, 34.88; H, 3.83; N, 12.52 Found: C, 34.93; H, 3.78; N, 12.76%. Selected IR data (KBr): 3414 (br, m(OH)), 2119(s, m(C„N)), 1634 (vs, m(C@N)), 1454 (m, m(C–N)), 1281 (vs, m(Cph– O)) cm1. Similar procedure was employed for the synthesis of complexes 1 and 2 with 73% and 75% yield, respectively. Anal. Calcd. for complex 1 C26H34CuFeLaN8O10 (876.91): C, 35.61; H, 3.91; N, 12.78 Found: C, 35.56; H, 3.85; N, 12.83%. Selected IR data (KBr): 3407 (br, m(OH)), 2116 (s, m(C„N)), 1634 (vs, m(C@N)), 1453 (m, m(C–N)), 1279 (vs, m(Cph–O)) cm1. Anal. Calcd. for complex 2 C26H34CuFeNdN8O10 (882.24): C, 35.40; H, 3.88; N, 12.70 Found: C, 35.35; H, 3.82; N, 12.80%. Selected IR data (KBr): 3399 (br, m(OH)), 2116 (s, m(C„N)), 1634 (vs, m(C@N)), 1455 (m, m(C–N)), 1278 (vs, m(Cph–O)) cm1. [10] Crystal date of 1: C26H34CuFeLaN8O10, Mr = 876.91, triclinic system, space a = 9.313(2) Å, b = 11.557(2) Å, c = 16.118(3) Å, b = 84.98(3)°, group P 1, V = 1695.3(6) Å3, Z = 2, Dc = 1.718 Mg/cm3, l = 2.344 mm1, 3.04 < h < 25.00°, F(0 0 0) = 876, R1 = 0.0351, wR2 = 0.1161, [I > 2r(I)]. The intensity data were collected on a Rigaku R-AXIS RAPID diffractometer with Mo/ka radiation (k = 0.71073 Å, graphite monochromator) at 293(2) K using x-scan mode. The structure was solved by direct methods and refined by full-matrix least
[11]
[12]
[13] [14]
squares on F2 using SHELXTL97 software. Empirical adsorption correction was applied for all date. The heaviest atoms were first found. Atoms O, N and C were subsequently located in difference Fourier maps. All non-hydrogen atoms were refined anisotropically. Crystal date of 2: C26H34CuFeN8NdO10, a = 9.300(4) Å, b = 11.475(6) Å, Mr = 882.24, triclinic system, space group P 1, c = 15.985(8) Å, b = 85.175(7)°, V = 1665.6(14) Å3, Z = 2, Dc = 1.759 Mg/cm3, l = 2.662 mm1, 3.00 < h < 25.00°, F(0 0 0) = 882, R1 = 0.0411, wR2 = 0.0859. Crystal date of 3: C26H34CuFeGdN8O10, Mr = 895.25, triclinic system, space a = 9.3170(4) Å, b = 11.4552(4) Å, c = 15.9053(6) Å, b = 85.2720(10)°, group P 1, V = 1657.72(11) Å3, Z = 2, Dc = 1.794 Mg/cm3, l = 3.109 mm1, 1.81 < h < 25.00°, F(0 0 0) = 890, R1 = 0.0286, wR2 = 0.0694. (a) S.W. Liang, M.X. Li, M. Shao, H.J. Liu, J. Mol. Struct. 841 (2007) 73; (b) J.A. Kautz, D.F. Mullica, B.P. Cunningham, R.A. Combs, J.M. Farmer, J. Mol. Struct. 523 (2000) 175; (c) W. Huang, D. Hu, S. Gou, H. Qian, H.K. Fun, S.S.S. Raj, Q. Meng, J. Mol. Struct. 649 (2003) 269. (a) A. Figuerola, J. Ribas, X. Solans, M. Font-Bardía, M. Maestro, C. Diaz, Eur. J. Inorg. Chem. (2006) 1846;; (b) R. Gheorghe, P. Cucos, M. Andruh, J.P. Costes, B. Donnadieu, S. Shova, Chem. Eur. J. 12 (2006) 187. A.R. Paital, W.T. Wong, G. Arom, D. Ray, Inorg. Chem. 46 (2007) 5727. A. Figuerola, C. Diaz, J. Ribas, V. Tangoulis, J. Granell, F. Lloret, J. Mahia, M. Maestro, Inorg. Chem. 42 (2003) 641.
Contents lists available at ScienceDirect
Inorganic Chemistry Communications journal homepage: www.elsevier.com/locate/inoche
One-dimensional salen-type heterospin trimetallic (3d–4f–3d0 ) chain-like coordination polymers: Syntheses, crystal structures and magnetic properties Wen-Bin Sun a, Peng-Fei Yan a,*, Guang-Ming Li a, Ju-Wen Zhang a, Ting Gao a, Masayuki Suda b, Yasuaki Einaga b,* a
Key Laboratory of Functional Inorganic Material Chemistry (HLJU), Ministry of Education, School of Chemistry and Materials Science, Heilongjiang University, No. 74, Xuefu Road, Nangang District, Harbin 150080, PR China Keio University, 3-14-1 Hiyoshi, Yokohama 223-8522, Japan
b
a r t i c l e
i n f o
Article history: Received 17 July 2009 Accepted 13 November 2009 Available online 17 November 2009 Keywords: Salen-type ligand Heterospin Trimetallic polymer Structure Magnetic properties
a b s t r a c t Three one-dimensional (1D) heterospin trimetallic chain-like polymers [{LCu(H2O)}Ln(MeOH)(H2O)2{(lCN)2Fe(CN)4}]2H2O (1, Ln = La; 2, Ln = Nd; 3, Ln = Gd) were prepared by substitution of the nitrato ligands in [LCuLn] complexes with [Fe(CN)6]3 ions (H2L = N,N0 -bis(3-methoxysalicylidene)propane-1,2diamine). Single-crystal X-ray diffraction analysis revealed that the methyl on the salen-type ligand impeded the connection between cyanide groups and Cu(II) ions efficiently. Consequently, three novel one-dimensional (1D) trimetallic chain-like polymers were obtained with the linker [Fe(CN)6]3 ions interacting only with the lanthanide ions. The magnetic investigation for 3 indicated a ferrimagnetic chain may form. Ó 2009 Elsevier B.V. All rights reserved.
The design and construction of supramolecular solid-state architectures with heterospin carriers are of high interest in the field of molecular magnetism [1]. However, the number of heterospin coordination polymers is limited to a few examples [1a,2]. The first trimetallic 3d–3d0 –3d00 complexes were reported by Chaudhuri and co-workers [3]. Recently, Costes and Andruh and co-workers are developing a synthetic approach aiming at obtaining heterospin multinuclear complexes. It is based on the employment of bimetallic d–f complexes as starting materials, with the nitrato groups being replaced by the hexacyanometallates [M(CN)6]3 (M = Cr(III), Fe(III), Co(III)) carrying the third spin carrier. Under this strategy, the first 2p–3d–4f heterospin system, 3d–3d0 –4f trimetallic and 3p–3d–4f complexes have been obtained [4,2c,5]. Since the cyanide nitrogen atoms of the hexacyanometallates are strong donor groups that could link both transition metal and lanthanide ions, most of the heterospin coordination polymers constructed by the hexacyanometallates are multidimensional [1]. From a magnetic point of view, the understanding of the magnetic properties correlating to structure is still far from being satisfactory [1a]. Thus, using of blocking organic ligands to reduce the dimensionality of heterospin coordination polymers is deserved to be further investigated for the purpose of clearly elucidating
* Corresponding authors. Tel.: +86 451 86608399; fax: +86 451 86608042 (P.-F. Yan). E-mail addresses: [email protected] (P.-F. Yan), [email protected] (Y. Einaga). 1387-7003/$ - see front matter Ó 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.inoche.2009.11.006
magneto-structural correlations and preparing interesting molecular materials such as single-molecule magnets (SMMs) and singlechain magnets (SCMs) [1b,1c]. We are exploring a strategy to control the solid structure of salen-type 4f and 3d–4f complexes and study their physicochemical properties [6]. In order to obtain the low-dimensional heterospin coordination polymer, a salen-type ligand with a methyl on the lateral alkane diamino chain was used. The steric influence of methyl impeded the linking between cyanide groups and Cu(II) ions successfully, and consequently three 1D trimetallic chain-like polymers were obtained. We herein present the syntheses, crystal structures and magnetic properties of the complexes. The starting heterodinuclear [LCuGd] (H2L = N,N0 -bis(3-methoxysalicylidene)propane-1,2-diamine) complexes were prepared according to literatures [6b,7,8]. The trimetallic coordination polymers 1–3 were easily prepared [2c,9] by diffusion of a methanol solution of [LCuGd] complexes to an aqueous solution of K3[Fe(CN)6]. The resulting dark-green micro-crystalline precipitate was filtered and characterized by single-crystal X-ray diffraction [10], elemental analysis, FT-Infrared (IR) spectrum (Fig. S1) and thermogravimetric analysis (TGA). The IR spectra of complexes 1–3 exhibit broad absorptions centered at 3410 cm1 associated with the O–H stretching vibrations of H2O molecules in this structure. The band centered at 1634 cm1 is attributed to the characteristic stretching vibration of the imine (C@N) group. The single peak that appears at around 2119 cm1 is assigned to the m(C„N) stretching mode of the cyanide group in accordance with
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the literatures [11]. Single-crystal X-ray diffraction analysis reveals that complexes 1–3 are isomorphic. Take complex 3 as an example to describe their structures, which crystallizes in the triclinic P1 space group. A perspective view of the complex 3 with the atomlabeling scheme and selected bond lengths and angles is given in Fig. 1. The [LCuGd] moiety preserves the structural features of the whole [Cu(II)Ln(III)] family of complexes with compartmental salen-type ligands [7,8]. The Cu(II) ion is hosted in the inner N2O2 compartment, and the oxophilic Gd(III) ion occupies the outer O4 cavity. The two metal ions are doubly bridged through sharing the two phenolic oxygen atoms from the ligand. The Cu–Gd distance is 3.4301 Å which is shorter than 3.5083 Å of the first salen-type 3d–3d0 –4f complex [Cu(salpn)Gd(H2O)3 {Fe(CN)6}]4H2O(salpn2 = N,N0 -propylenedi(3-methoxysalicylidenei-minato) [2c].
Fig. 1. Perspective view of the coordination environment of the Cu(II), Gd(III) and Fe(III) centers in 3 with atoms represented by 30% thermal ellipsoids. Selected bond lengths (Å) and angles (°): Cu(1)–N(1) 1.908(4), Cu(1)–N(2) 1.918(4), Cu(1)–O(1) 1.925(3), Cu(1)–O(3) 1.904(3), Cu(1)–O(5) 1.941(4), Gd(1)–O(1) 2.372(3), Gd(1)– O(3) 2.377(3), Gd(1)–O(2) 2.701(3), Gd(1)–O(4) 2.628(3), Gd(1)–N(5) 2.469(4), Gd(1)–N(6), 2.553(3), Gd(1)–O(6) 2.423(3), Gd(1)–O(7) 2.444(3), Gd(1)–O(8) 2.424(3), Fe(1)–C(20) 1.941(4), Fe(1)–C(21) 1.943(5), Fe(1)–C(22) 1.946(5), Fe(2)– C(23) 1.941(4), Fe(2)–C(24) 1.943(5), Fe(2)–C(25) 1.944(4), N(5)–C(20) 1.149(5), N(6)–C(23) 1.147(5), Gd(1)–N(5)–C(20) 171.80(3), Gd(1)–N(6)–C(23) 146.90(3), Fe(2)–C(23)–N(6) 172.78(3), Fe(1)–C(20)–N(5) 178.04(4), O(1)–Gd(1)–O(2) 61.34(9), O(3)–Gd(1)–O(4) 60.83(9), Cu(1)–O(1)–Gd(1) 105.47(11), Cu(1)–O(3)– Gd(1) 105.95(11). Selected bond lengths and angles of 1 and 2 listed in Table S1.
Since the steric effect of methyl on the lateral alkane diamino chain of the ligand, the cyanide groups interacts only with the Gd(III) ions not Cu(II) ions. A schematic view of the chain of [LCuGdFe]n is shown in Fig. 2. Each [Fe(CN)6]3 unit attaches two Gd(III) ions using two trans cyanide groups, while each [LCuGd] group connects two [Fe(CN)6]3 moieties in a cis fashion. The chains show an alternation of [{LCu(H2O)}Gd(MeOH)(H2O)2] and [Fe(CN)6]3 fragments linked by cyanide bridges in the transgeometry. The angels Fe(1)–C(20)„N(5) and Fe(2)–C(23)„N(6) are 178.04° and 172.78°, which indicates a bent cyanide bridge due to the steric hindrance of the [LCuGd] entity. The angles Gd– Fe–Gd and Fe–Gd–Fe are different (180.00° and 122.61°) along the chain. The chains are not in a linear configuration and trinuclear entities [GdFeGd] run along the chain in a zigzag path. As each Gd(III) ion is related to the neighboring one by a glide plane, there are two enantiomeric coordination spheres in a chain, which is similar to some [CuGd] coordination polymers [12]. To our knowledge, one of the closed related complexes to 1–3 is the heterotrinuclear complex [Cu(salpn)Gd(H2O)3{Fe(CN)6}]4H2O [2c]. However, the crystallographic analysis revealed that their structures are very different. Firstly, the polymeric structure of [Cu(salpn)Gd(H2O)3{Fe(CN)6}]4H2O has a ladder topology built up of [Gd2Fe2Cu] pentagous that share the [FeGd] edges. Each [Fe(CN)6]3 group connects three heterodinuclear [CuGd] units with the cyanide groups linking both the Cu(II) and lanthanide(III) ions. Complex 1–3 prefer to be, however, a unique 1D chain-like structure through trans cyanide bridges between lanthanide(III) and iron(III) ions. Secondly, the Gd(III) ions in [Cu(salpn)Gd(H2O)3{Fe(CN)6}]4H2O are eight-coordinated while lanthanide(III) ions in 1–3 are nine-coordinated. Obviously, the above mentioned differences are attributed to the size of lanthanide ions and the selected ligand. In complex 3, the distances between metal ions of adjacent chains are separate distinctly with the shortest distance 7.1198 Å (Cu–Fe), 9.1785 Å (Cu–Cu) and 9.7849 Å (Cu–Gd), respectively (Fig. 2). Furthermore, there are coordinated and interstitial waters between the chains in complexes 1–3 and each aqua molecule is hydrogen-bonded to uncoordinated cyanide nitrogen atom of an adjacent chain [O–H–N] and gives an extensive 3D network (Fig. S2). Thermogravimetric analysis (TGA) result indicates that the aqua molecules can be removed before 200 °C with the weight loss of 13.5%, which is consistent with the calculated value 13.6% (Table S2 and Fig. S3). Next, magnetic susceptibility data for 3 were collected in the temperature range 2–300 K at an applied field of 1000 Oe. The
Fig. 2. Perspective view of chains in 3, along with the distances between metal ions of adjacent chain.
W.-B. Sun et al. / Inorganic Chemistry Communications 13 (2010) 171–174
temperature-dependent magnetic susceptibility of 3 in the forms of vmT versus T and v1 m versus T plots are shown in Fig. 3. The value of the vmT product is 8.68 emu mol1 K at room temperature, which is slightly higher than the calculated value (8.62 emu mol1 K) corresponding to the sum of the contributions of the three uncoupled ions, (vmT)HT = (Ng2b2/3k)[SGd(SGd + 1) + SCu (SCu + 1) + SFe(SFe + 1)], gCu = gGd = gFe = 2 [2c]. The similar deviation from calculated value is also found in the first salen-type 3d–4f– 3d0 complex [Cu(salpn)Gd(H2O)3{Fe(CN)6}]4H2O, which contributes to the first-order orbital momentum of the low-spin iron(III) [2c]. The vmT value keeps increase slowly until 90.1 K, where it starts to increase abruptly and reaches a maximum of 9.53 emu mol1 K at 13.9 K. The increase of vmT with a decrease in the temperature suggests the presence of ferromagnetic interactions between paramagnetic centers. The maximum vmT value 9.53 emu mol1 K at 13.9 K is lower than that of complex [Cu(salpn)Gd(H2O)3{Fe(CN)6}]4H2O (9.86 emu mol1 K at 13.8 K) [2c], which should be attributed to the different structure of them. Below 13.9 K, vmT decreases with cooling, first slightly and then abruptly, down to 9.23 emu mol1 K at 2 K. The thermal evolution of v1 m obeyed the Curie-Weiss law, vm = C/(T h), in the temperature range from 13.9 K to room temperature, with the Weiss constant, h, of 0.69 K, the Curie constant, C of 8.65 emu mol1 K. The positive h value suggests a ferromagnetic coupling in 3. This behavior is consistent with that of trimetallic complex [Cu(salpn)Gd(H2O)3{Fe(CN)6}]4H2O [2c]. In light of the literature [2c], a interpretation of the magnetic behavior of 3 is given as follows: above 13.9 K, the Cu(II) and Gd(III) ions are ferromagnetically coupled, resulting in units with S = 4. Below 13.9 K, the vmT product decrease rapidly. This behavior is most likely caused by any the [LCuGd] units further interact antiferromagnetically with the paramagnetic [Fe(CN)6]3 linkers[2c,13], the interchain interaction, the zero-field splitting (ZFS) of the metal centers, or all at the same time [13]. According to the crystal structure of 3 (Fig. 2), the distances between metal ions of adjacent chains are separate obviously and there are no cyanide groups coordinated to Cu(II) ions, which assumes that no magnetic interaction occurs between Cu(II) and Fe(III). Besides, the Gd(III)–NC–Fe(III) chain-like pathway is effective, which is similar to some investigations of [Gd(III)Fe(III)] cyanide-bridged systems [14]. However, the Gd(III)–NC–Fe(III) interaction is supposed to be much weaker than that of Cu(II)– Gd(III) [14]. In combination with the chain-like structural properties, a ferrimagnetic chain [(S = 4)–(S = 1/2)–(S = 4)–(S = 1/2)– ] may form.
Fig. 3. The plots of vmT and v1 m versus T for 3 from 2.0 to 300 K. The solid line represents the best fit to the Curie–Weiss law and the plot of M versus H for 3 at 2 K is inserted.
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To confirm the magnetic behavior of 3, AC magnetic susceptibility and FC-ZFC magnetization measurements were performed. The results are plotted in Figs. S4 and S5. The real v0 and imaginary v00 components of AC magnetic susceptibility do not show any peaks and frequency dependence. The FC-ZFC magnetization curves do not diverge either. These results indicate that there is no magnetic ordering in 3 until 2 K. The field dependence of the magnetization for 3 at 2 K shows the magnetization reaches rapidly saturation at a magnetization value of 8.3 Nb (Fig. 3). The value consist of the saturation value of 8 Nb from the [LCuGd] units (SGd(III) = 7/2, SCu(II) = 1/2, g = 2) and 0.3 Nb of first-order orbital momentum for the low-spin iron(III) [2c]. The M versus H loop curve indicates that no hysteresis is observed (Fig. S6). In summary, three heterospin trimetallic polymers have been prepared and characterized crystallographically and magnetically. Three polymers show a novel chain-like structure formed by the [Fe(CN)6]3 ions bridging between the lanthanide(III) ions. The present work will be helpful in providing valuable information for the design and synthesis of low-dimensional cyanide-bridged heterospin multinuclear polymers. Further magnetic investigation on the new family of polymers is in progress. Acknowledgments This work is financially supported by the National Natural Science Foundation of China (Nos. 20672032 and 50903028), Heilongjiang Province (Nos. QC08C10, GZ08A401, JC200605, 2006FRFLXG031 and 2009RFXXG201), and Key Laboratory of Environment-friendly Chemical Engineering Technology of Heilongjiang Higher Education Institutes, Heilongjiang University. Authors want to thank Prof. Fu-Pei Liang (Guangxi Normal University) for the magnetic measurement. Appendix A. Supplementary material CCDC 625266, 681053, 732858 contain the supplementary crystallographic data for compounds 1, 2, 3, respectively. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif. Supplementary data associated with this article can be found, in the online version, at doi:10.1016/j.inoche.2009.11.006. References [1] (a) M. Andruh, J.P. Costes, C. Diaz, S. Gao, Inorg. Chem. 48 (2009) 3342; (b) D.P. Zhang, H.L. Wang, Y.T. Chen, Z.H. Ni, L.J. Tian, J.Z. Jiang, Inorg. Chem. 48 (2009) 5488; (c) S. Tanase, J. Reedijk, Coord. Chem. Rev. 250 (2006) 2501; (d) D.F. Mullica, J.M. Farmer, J.A. Kautz, Inorg. Chem. Commun. 2 (1999) 73. [2] (a) H.Z. Kou, B.C. Zhou, S. Gao, R.J. Wang, Angew. Chem., Int. Ed. 42 (2003) 3288; (b) H.Z. Kou, B.C. Zhou, R.J. Wang, Inorg. Chem. 42 (2003) 7658; (c) R. Gheorghe, M. Andruh, J.P. Costes, B. Donnadieu, Chem. Commun. (2003) 2778; (d) T. Shiga, H. Okawa, S. Kitagawa, M. Ohba, J. Am. Chem. Soc. 128 (2006) 16426. [3] (a) C.N. Verani, T. Weyhermüller, E. Rentschler, E. Bill, P. Chaudhuri, Chem. Commun. (1998) 2475; (b) C.N. Verani, E. Rentschler, T. Weyhermüller, E. Bill, P.J. Chaudhuri, Chem. Soc. Dalton Trans. (2000) 4263. [4] A.M. Madalan, H.W. Roesky, M. Andruh, M. Noltemeyer, N. Stanica, Chem. Commun. (2002) 1638. [5] A.M. Madalan, N. Avarvari, M. Fourmigué, R. Clérac, L.F. Chibotaru, S. Clima, M. Andruh, Inorg. Chem. 47 (2008) 940. [6] (a) W.B. Sun, P.F. Yan, G.M. Li, H. Xu, J.W. Zhang, J. Solid State Chem. 182 (2009) 381; (b) W.B. Sun, P.F. Yan, G.M. Li, J.W. Zhang, H. Xu, Inorg. Chim. Acta 362 (2009) 1761; (c) T. Gao, P.F. Yan, G.M. Li, G.F. Hou, J.S. Gao, Polyhedron 26 (2007) 5382; (d) P.F. Yan, W.B. Sun, G.M. Li, C.H. Nie, T. Gao, Z.Y. Yue, J. Coord. Chem. 60 (2007) 1973. [7] J.P. Costes, F. Dahan, A. Dupuis, J.P. Laurent, Inorg. Chem. 35 (1996) 2400.
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[8] H. Kara, Y. Elerman, K. Prout, Z. Naturforsch. 55b (2000) 1131. [9] [{LCu(H2O)}Gd(MeOH)(H2O)2{(l-CN)2Fe(CN)4}]2H2O (3) To a MeOH solution (10 mL) of [LCu(Me2CO)Gd(NO3)3] (0.2054 g, 0.25 mmol) was slowly diffused an aqueous solution (6 mL) of K3[Fe(CN)6] (0.0820 g, 0.25 mmol) at room temperature. A dark green crystals formed in one week. Dark green crystals were collected by filtration and washed with water with a 70% yield. Anal. Calcd. for complex 3 C26H34CuFeGdN8O10 (895.25): C, 34.88; H, 3.83; N, 12.52 Found: C, 34.93; H, 3.78; N, 12.76%. Selected IR data (KBr): 3414 (br, m(OH)), 2119(s, m(C„N)), 1634 (vs, m(C@N)), 1454 (m, m(C–N)), 1281 (vs, m(Cph– O)) cm1. Similar procedure was employed for the synthesis of complexes 1 and 2 with 73% and 75% yield, respectively. Anal. Calcd. for complex 1 C26H34CuFeLaN8O10 (876.91): C, 35.61; H, 3.91; N, 12.78 Found: C, 35.56; H, 3.85; N, 12.83%. Selected IR data (KBr): 3407 (br, m(OH)), 2116 (s, m(C„N)), 1634 (vs, m(C@N)), 1453 (m, m(C–N)), 1279 (vs, m(Cph–O)) cm1. Anal. Calcd. for complex 2 C26H34CuFeNdN8O10 (882.24): C, 35.40; H, 3.88; N, 12.70 Found: C, 35.35; H, 3.82; N, 12.80%. Selected IR data (KBr): 3399 (br, m(OH)), 2116 (s, m(C„N)), 1634 (vs, m(C@N)), 1455 (m, m(C–N)), 1278 (vs, m(Cph–O)) cm1. [10] Crystal date of 1: C26H34CuFeLaN8O10, Mr = 876.91, triclinic system, space a = 9.313(2) Å, b = 11.557(2) Å, c = 16.118(3) Å, b = 84.98(3)°, group P 1, V = 1695.3(6) Å3, Z = 2, Dc = 1.718 Mg/cm3, l = 2.344 mm1, 3.04 < h < 25.00°, F(0 0 0) = 876, R1 = 0.0351, wR2 = 0.1161, [I > 2r(I)]. The intensity data were collected on a Rigaku R-AXIS RAPID diffractometer with Mo/ka radiation (k = 0.71073 Å, graphite monochromator) at 293(2) K using x-scan mode. The structure was solved by direct methods and refined by full-matrix least
[11]
[12]
[13] [14]
squares on F2 using SHELXTL97 software. Empirical adsorption correction was applied for all date. The heaviest atoms were first found. Atoms O, N and C were subsequently located in difference Fourier maps. All non-hydrogen atoms were refined anisotropically. Crystal date of 2: C26H34CuFeN8NdO10, a = 9.300(4) Å, b = 11.475(6) Å, Mr = 882.24, triclinic system, space group P 1, c = 15.985(8) Å, b = 85.175(7)°, V = 1665.6(14) Å3, Z = 2, Dc = 1.759 Mg/cm3, l = 2.662 mm1, 3.00 < h < 25.00°, F(0 0 0) = 882, R1 = 0.0411, wR2 = 0.0859. Crystal date of 3: C26H34CuFeGdN8O10, Mr = 895.25, triclinic system, space a = 9.3170(4) Å, b = 11.4552(4) Å, c = 15.9053(6) Å, b = 85.2720(10)°, group P 1, V = 1657.72(11) Å3, Z = 2, Dc = 1.794 Mg/cm3, l = 3.109 mm1, 1.81 < h < 25.00°, F(0 0 0) = 890, R1 = 0.0286, wR2 = 0.0694. (a) S.W. Liang, M.X. Li, M. Shao, H.J. Liu, J. Mol. Struct. 841 (2007) 73; (b) J.A. Kautz, D.F. Mullica, B.P. Cunningham, R.A. Combs, J.M. Farmer, J. Mol. Struct. 523 (2000) 175; (c) W. Huang, D. Hu, S. Gou, H. Qian, H.K. Fun, S.S.S. Raj, Q. Meng, J. Mol. Struct. 649 (2003) 269. (a) A. Figuerola, J. Ribas, X. Solans, M. Font-Bardía, M. Maestro, C. Diaz, Eur. J. Inorg. Chem. (2006) 1846;; (b) R. Gheorghe, P. Cucos, M. Andruh, J.P. Costes, B. Donnadieu, S. Shova, Chem. Eur. J. 12 (2006) 187. A.R. Paital, W.T. Wong, G. Arom, D. Ray, Inorg. Chem. 46 (2007) 5727. A. Figuerola, C. Diaz, J. Ribas, V. Tangoulis, J. Granell, F. Lloret, J. Mahia, M. Maestro, Inorg. Chem. 42 (2003) 641.